audk/OvmfPkg/IoMmuDxe/AmdSevIoMmu.c

911 lines
30 KiB
C
Raw Normal View History

/** @file
The protocol provides support to allocate, free, map and umap a DMA buffer
for bus master (e.g PciHostBridge). When SEV is enabled, the DMA operations
must be performed on unencrypted buffer hence we use a bounce buffer to map
the guest buffer into an unencrypted DMA buffer.
Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
Copyright (c) 2017, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include "AmdSevIoMmu.h"
#define MAP_INFO_SIG SIGNATURE_64 ('M', 'A', 'P', '_', 'I', 'N', 'F', 'O')
typedef struct {
UINT64 Signature;
LIST_ENTRY Link;
EDKII_IOMMU_OPERATION Operation;
UINTN NumberOfBytes;
UINTN NumberOfPages;
EFI_PHYSICAL_ADDRESS CryptedAddress;
EFI_PHYSICAL_ADDRESS PlainTextAddress;
} MAP_INFO;
//
OvmfPkg/IoMmuDxe: track all mappings The "mRecycledMapInfos" list implements an internal pool of unused MAP_INFO structures between the IoMmuUnmap() and IoMmuMap() functions. The original goal was to allow IoMmuUnmap() to tear down CommonBuffer mappings without releasing any memory: IoMmuUnmap() would recycle the MAP_INFO structure to the list, and IoMmuMap() would always check the list first, before allocating a brand new MAP_INFO structure. In one of the following patches, we'll change OvmfPkg/IoMmuDxe so that it unmaps all existent bus master operations (CommonBuffer, Read, Write) at ExitBootServices(), strictly after the individual device drivers abort pending DMA on the devices they manage, in their own ExitBootServices() notification functions. For this, rename and repurpose the list to track all live mappings. This means that IoMmuUnmap() will always release a MAP_INFO structure (even when cleaning up a CommonBuffer operation). That's fine (for now), because device drivers are no longer expected to call Unmap() in their ExitBootServices() notification functions. In theory, we could also move the allocation and freeing of the stash buffer from IoMmuAllocateBuffer() and IoMmuFreeBuffer(), respectively, to IoMmuMap() and IoMmuUnmap(). However, this would require allocating and freeing a stash buffer in *both* IoMmuMap() and IoMmuUnmap(), as IoMmuMap() performs in-place decryption for CommonBuffer operations, and IoMmuUnmap() performs in-place encryption for the same. By keeping the stash buffer allocation as-is, not only do we keep the code almost fully undisturbed, but - we also continue to guarantee that IoMmuUnmap() succeeds: allocating a stash buffer in IoMmuUnmap(), for in-place encryption after a CommonBuffer operation, could fail; - we also keep IoMmuUnmap() largely reusable for ExitBootServices() callback context: allocating a stash buffer in IoMmuUnmap() would simply be forbidden in that context. Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com>
2017-09-07 15:30:19 +02:00
// List of the MAP_INFO structures that have been set up by IoMmuMap() and not
// yet torn down by IoMmuUnmap(). The list represents the full set of mappings
// currently in effect.
//
OvmfPkg/IoMmuDxe: track all mappings The "mRecycledMapInfos" list implements an internal pool of unused MAP_INFO structures between the IoMmuUnmap() and IoMmuMap() functions. The original goal was to allow IoMmuUnmap() to tear down CommonBuffer mappings without releasing any memory: IoMmuUnmap() would recycle the MAP_INFO structure to the list, and IoMmuMap() would always check the list first, before allocating a brand new MAP_INFO structure. In one of the following patches, we'll change OvmfPkg/IoMmuDxe so that it unmaps all existent bus master operations (CommonBuffer, Read, Write) at ExitBootServices(), strictly after the individual device drivers abort pending DMA on the devices they manage, in their own ExitBootServices() notification functions. For this, rename and repurpose the list to track all live mappings. This means that IoMmuUnmap() will always release a MAP_INFO structure (even when cleaning up a CommonBuffer operation). That's fine (for now), because device drivers are no longer expected to call Unmap() in their ExitBootServices() notification functions. In theory, we could also move the allocation and freeing of the stash buffer from IoMmuAllocateBuffer() and IoMmuFreeBuffer(), respectively, to IoMmuMap() and IoMmuUnmap(). However, this would require allocating and freeing a stash buffer in *both* IoMmuMap() and IoMmuUnmap(), as IoMmuMap() performs in-place decryption for CommonBuffer operations, and IoMmuUnmap() performs in-place encryption for the same. By keeping the stash buffer allocation as-is, not only do we keep the code almost fully undisturbed, but - we also continue to guarantee that IoMmuUnmap() succeeds: allocating a stash buffer in IoMmuUnmap(), for in-place encryption after a CommonBuffer operation, could fail; - we also keep IoMmuUnmap() largely reusable for ExitBootServices() callback context: allocating a stash buffer in IoMmuUnmap() would simply be forbidden in that context. Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com>
2017-09-07 15:30:19 +02:00
STATIC LIST_ENTRY mMapInfos = INITIALIZE_LIST_HEAD_VARIABLE (mMapInfos);
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
#define COMMON_BUFFER_SIG SIGNATURE_64 ('C', 'M', 'N', 'B', 'U', 'F', 'F', 'R')
//
// ASCII names for EDKII_IOMMU_OPERATION constants, for debug logging.
//
STATIC CONST CHAR8 * CONST
mBusMasterOperationName[EdkiiIoMmuOperationMaximum] = {
"Read",
"Write",
"CommonBuffer",
"Read64",
"Write64",
"CommonBuffer64"
};
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
//
// The following structure enables Map() and Unmap() to perform in-place
// decryption and encryption, respectively, for BusMasterCommonBuffer[64]
// operations, without dynamic memory allocation or release.
//
// Both COMMON_BUFFER_HEADER and COMMON_BUFFER_HEADER.StashBuffer are allocated
// by AllocateBuffer() and released by FreeBuffer().
//
#pragma pack (1)
typedef struct {
UINT64 Signature;
//
// Always allocated from EfiBootServicesData type memory, and always
// encrypted.
//
VOID *StashBuffer;
//
// Followed by the actual common buffer, starting at the next page.
//
} COMMON_BUFFER_HEADER;
#pragma pack ()
/**
Provides the controller-specific addresses required to access system memory
from a DMA bus master. On SEV guest, the DMA operations must be performed on
shared buffer hence we allocate a bounce buffer to map the HostAddress to a
DeviceAddress. The Encryption attribute is removed from the DeviceAddress
buffer.
@param This The protocol instance pointer.
@param Operation Indicates if the bus master is going to read or
write to system memory.
@param HostAddress The system memory address to map to the PCI
controller.
@param NumberOfBytes On input the number of bytes to map. On output
the number of bytes that were mapped.
@param DeviceAddress The resulting map address for the bus master
PCI controller to use to access the hosts
HostAddress.
@param Mapping A resulting value to pass to Unmap().
@retval EFI_SUCCESS The range was mapped for the returned
NumberOfBytes.
@retval EFI_UNSUPPORTED The HostAddress cannot be mapped as a common
buffer.
@retval EFI_INVALID_PARAMETER One or more parameters are invalid.
@retval EFI_OUT_OF_RESOURCES The request could not be completed due to a
lack of resources.
@retval EFI_DEVICE_ERROR The system hardware could not map the requested
address.
**/
EFI_STATUS
EFIAPI
IoMmuMap (
IN EDKII_IOMMU_PROTOCOL *This,
IN EDKII_IOMMU_OPERATION Operation,
IN VOID *HostAddress,
IN OUT UINTN *NumberOfBytes,
OUT EFI_PHYSICAL_ADDRESS *DeviceAddress,
OUT VOID **Mapping
)
{
EFI_STATUS Status;
MAP_INFO *MapInfo;
EFI_ALLOCATE_TYPE AllocateType;
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
COMMON_BUFFER_HEADER *CommonBufferHeader;
VOID *DecryptionSource;
DEBUG ((
DEBUG_VERBOSE,
"%a: Operation=%a Host=0x%p Bytes=0x%Lx\n",
__FUNCTION__,
((Operation >= 0 &&
Operation < ARRAY_SIZE (mBusMasterOperationName)) ?
mBusMasterOperationName[Operation] :
"Invalid"),
HostAddress,
(UINT64)((NumberOfBytes == NULL) ? 0 : *NumberOfBytes)
));
if (HostAddress == NULL || NumberOfBytes == NULL || DeviceAddress == NULL ||
Mapping == NULL) {
return EFI_INVALID_PARAMETER;
}
//
// Allocate a MAP_INFO structure to remember the mapping when Unmap() is
// called later.
//
OvmfPkg/IoMmuDxe: track all mappings The "mRecycledMapInfos" list implements an internal pool of unused MAP_INFO structures between the IoMmuUnmap() and IoMmuMap() functions. The original goal was to allow IoMmuUnmap() to tear down CommonBuffer mappings without releasing any memory: IoMmuUnmap() would recycle the MAP_INFO structure to the list, and IoMmuMap() would always check the list first, before allocating a brand new MAP_INFO structure. In one of the following patches, we'll change OvmfPkg/IoMmuDxe so that it unmaps all existent bus master operations (CommonBuffer, Read, Write) at ExitBootServices(), strictly after the individual device drivers abort pending DMA on the devices they manage, in their own ExitBootServices() notification functions. For this, rename and repurpose the list to track all live mappings. This means that IoMmuUnmap() will always release a MAP_INFO structure (even when cleaning up a CommonBuffer operation). That's fine (for now), because device drivers are no longer expected to call Unmap() in their ExitBootServices() notification functions. In theory, we could also move the allocation and freeing of the stash buffer from IoMmuAllocateBuffer() and IoMmuFreeBuffer(), respectively, to IoMmuMap() and IoMmuUnmap(). However, this would require allocating and freeing a stash buffer in *both* IoMmuMap() and IoMmuUnmap(), as IoMmuMap() performs in-place decryption for CommonBuffer operations, and IoMmuUnmap() performs in-place encryption for the same. By keeping the stash buffer allocation as-is, not only do we keep the code almost fully undisturbed, but - we also continue to guarantee that IoMmuUnmap() succeeds: allocating a stash buffer in IoMmuUnmap(), for in-place encryption after a CommonBuffer operation, could fail; - we also keep IoMmuUnmap() largely reusable for ExitBootServices() callback context: allocating a stash buffer in IoMmuUnmap() would simply be forbidden in that context. Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com>
2017-09-07 15:30:19 +02:00
MapInfo = AllocatePool (sizeof (MAP_INFO));
if (MapInfo == NULL) {
Status = EFI_OUT_OF_RESOURCES;
goto Failed;
}
//
// Initialize the MAP_INFO structure, except the PlainTextAddress field
//
ZeroMem (&MapInfo->Link, sizeof MapInfo->Link);
MapInfo->Signature = MAP_INFO_SIG;
MapInfo->Operation = Operation;
MapInfo->NumberOfBytes = *NumberOfBytes;
MapInfo->NumberOfPages = EFI_SIZE_TO_PAGES (MapInfo->NumberOfBytes);
MapInfo->CryptedAddress = (UINTN)HostAddress;
//
// In the switch statement below, we point "MapInfo->PlainTextAddress" to the
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
// plaintext buffer, according to Operation. We also set "DecryptionSource".
//
MapInfo->PlainTextAddress = MAX_ADDRESS;
AllocateType = AllocateAnyPages;
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
DecryptionSource = (VOID *)(UINTN)MapInfo->CryptedAddress;
switch (Operation) {
//
// For BusMasterRead[64] and BusMasterWrite[64] operations, a bounce buffer
// is necessary regardless of whether the original (crypted) buffer crosses
// the 4GB limit or not -- we have to allocate a separate plaintext buffer.
// The only variable is whether the plaintext buffer should be under 4GB.
//
case EdkiiIoMmuOperationBusMasterRead:
case EdkiiIoMmuOperationBusMasterWrite:
MapInfo->PlainTextAddress = BASE_4GB - 1;
AllocateType = AllocateMaxAddress;
//
// fall through
//
case EdkiiIoMmuOperationBusMasterRead64:
case EdkiiIoMmuOperationBusMasterWrite64:
//
// Allocate the implicit plaintext bounce buffer.
//
Status = gBS->AllocatePages (
AllocateType,
EfiBootServicesData,
MapInfo->NumberOfPages,
&MapInfo->PlainTextAddress
);
if (EFI_ERROR (Status)) {
goto FreeMapInfo;
}
break;
//
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
// For BusMasterCommonBuffer[64] operations, a to-be-plaintext buffer and a
// stash buffer (for in-place decryption) have been allocated already, with
// AllocateBuffer(). We only check whether the address of the to-be-plaintext
// buffer is low enough for the requested operation.
//
case EdkiiIoMmuOperationBusMasterCommonBuffer:
if ((MapInfo->CryptedAddress > BASE_4GB) ||
(EFI_PAGES_TO_SIZE (MapInfo->NumberOfPages) >
BASE_4GB - MapInfo->CryptedAddress)) {
//
// CommonBuffer operations cannot be remapped. If the common buffer is
// above 4GB, then it is not possible to generate a mapping, so return an
// error.
//
Status = EFI_UNSUPPORTED;
goto FreeMapInfo;
}
//
// fall through
//
case EdkiiIoMmuOperationBusMasterCommonBuffer64:
//
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
// The buffer at MapInfo->CryptedAddress comes from AllocateBuffer().
//
MapInfo->PlainTextAddress = MapInfo->CryptedAddress;
//
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
// Stash the crypted data.
//
CommonBufferHeader = (COMMON_BUFFER_HEADER *)(
(UINTN)MapInfo->CryptedAddress - EFI_PAGE_SIZE
);
ASSERT (CommonBufferHeader->Signature == COMMON_BUFFER_SIG);
CopyMem (
CommonBufferHeader->StashBuffer,
(VOID *)(UINTN)MapInfo->CryptedAddress,
MapInfo->NumberOfBytes
);
//
// Point "DecryptionSource" to the stash buffer so that we decrypt
// it to the original location, after the switch statement.
//
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
DecryptionSource = CommonBufferHeader->StashBuffer;
break;
default:
//
// Operation is invalid
//
Status = EFI_INVALID_PARAMETER;
goto FreeMapInfo;
}
//
// Clear the memory encryption mask on the plaintext buffer.
//
Status = MemEncryptSevClearPageEncMask (
0,
MapInfo->PlainTextAddress,
MapInfo->NumberOfPages,
TRUE
);
ASSERT_EFI_ERROR (Status);
if (EFI_ERROR (Status)) {
CpuDeadLoop ();
}
//
// If this is a read operation from the Bus Master's point of view,
// then copy the contents of the real buffer into the mapped buffer
// so the Bus Master can read the contents of the real buffer.
//
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
// For BusMasterCommonBuffer[64] operations, the CopyMem() below will decrypt
// the original data (from the stash buffer) back to the original location.
//
if (Operation == EdkiiIoMmuOperationBusMasterRead ||
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
Operation == EdkiiIoMmuOperationBusMasterRead64 ||
Operation == EdkiiIoMmuOperationBusMasterCommonBuffer ||
Operation == EdkiiIoMmuOperationBusMasterCommonBuffer64) {
CopyMem (
(VOID *) (UINTN) MapInfo->PlainTextAddress,
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
DecryptionSource,
MapInfo->NumberOfBytes
);
}
OvmfPkg/IoMmuDxe: track all mappings The "mRecycledMapInfos" list implements an internal pool of unused MAP_INFO structures between the IoMmuUnmap() and IoMmuMap() functions. The original goal was to allow IoMmuUnmap() to tear down CommonBuffer mappings without releasing any memory: IoMmuUnmap() would recycle the MAP_INFO structure to the list, and IoMmuMap() would always check the list first, before allocating a brand new MAP_INFO structure. In one of the following patches, we'll change OvmfPkg/IoMmuDxe so that it unmaps all existent bus master operations (CommonBuffer, Read, Write) at ExitBootServices(), strictly after the individual device drivers abort pending DMA on the devices they manage, in their own ExitBootServices() notification functions. For this, rename and repurpose the list to track all live mappings. This means that IoMmuUnmap() will always release a MAP_INFO structure (even when cleaning up a CommonBuffer operation). That's fine (for now), because device drivers are no longer expected to call Unmap() in their ExitBootServices() notification functions. In theory, we could also move the allocation and freeing of the stash buffer from IoMmuAllocateBuffer() and IoMmuFreeBuffer(), respectively, to IoMmuMap() and IoMmuUnmap(). However, this would require allocating and freeing a stash buffer in *both* IoMmuMap() and IoMmuUnmap(), as IoMmuMap() performs in-place decryption for CommonBuffer operations, and IoMmuUnmap() performs in-place encryption for the same. By keeping the stash buffer allocation as-is, not only do we keep the code almost fully undisturbed, but - we also continue to guarantee that IoMmuUnmap() succeeds: allocating a stash buffer in IoMmuUnmap(), for in-place encryption after a CommonBuffer operation, could fail; - we also keep IoMmuUnmap() largely reusable for ExitBootServices() callback context: allocating a stash buffer in IoMmuUnmap() would simply be forbidden in that context. Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com>
2017-09-07 15:30:19 +02:00
//
// Track all MAP_INFO structures.
//
InsertHeadList (&mMapInfos, &MapInfo->Link);
//
// Populate output parameters.
//
*DeviceAddress = MapInfo->PlainTextAddress;
*Mapping = MapInfo;
DEBUG ((
DEBUG_VERBOSE,
"%a: Mapping=0x%p Device(PlainText)=0x%Lx Crypted=0x%Lx Pages=0x%Lx\n",
__FUNCTION__,
MapInfo,
MapInfo->PlainTextAddress,
MapInfo->CryptedAddress,
(UINT64)MapInfo->NumberOfPages
));
return EFI_SUCCESS;
FreeMapInfo:
FreePool (MapInfo);
Failed:
*NumberOfBytes = 0;
return Status;
}
/**
Completes the Map() operation and releases any corresponding resources.
This is an internal worker function that only extends the Map() API with
the MemoryMapLocked parameter.
@param This The protocol instance pointer.
@param Mapping The mapping value returned from Map().
@param MemoryMapLocked The function is executing on the stack of
gBS->ExitBootServices(); changes to the UEFI
memory map are forbidden.
@retval EFI_SUCCESS The range was unmapped.
@retval EFI_INVALID_PARAMETER Mapping is not a value that was returned by
Map().
@retval EFI_DEVICE_ERROR The data was not committed to the target system
memory.
**/
STATIC
EFI_STATUS
EFIAPI
IoMmuUnmapWorker (
IN EDKII_IOMMU_PROTOCOL *This,
IN VOID *Mapping,
IN BOOLEAN MemoryMapLocked
)
{
MAP_INFO *MapInfo;
EFI_STATUS Status;
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
COMMON_BUFFER_HEADER *CommonBufferHeader;
VOID *EncryptionTarget;
DEBUG ((
DEBUG_VERBOSE,
"%a: Mapping=0x%p MemoryMapLocked=%d\n",
__FUNCTION__,
Mapping,
MemoryMapLocked
));
if (Mapping == NULL) {
return EFI_INVALID_PARAMETER;
}
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
MapInfo = (MAP_INFO *)Mapping;
//
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
// set CommonBufferHeader to suppress incorrect compiler/analyzer warnings
//
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
CommonBufferHeader = NULL;
//
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
// For BusMasterWrite[64] operations and BusMasterCommonBuffer[64] operations
// we have to encrypt the results, ultimately to the original place (i.e.,
// "MapInfo->CryptedAddress").
//
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
// For BusMasterCommonBuffer[64] operations however, this encryption has to
// land in-place, so divert the encryption to the stash buffer first.
//
EncryptionTarget = (VOID *)(UINTN)MapInfo->CryptedAddress;
switch (MapInfo->Operation) {
case EdkiiIoMmuOperationBusMasterCommonBuffer:
case EdkiiIoMmuOperationBusMasterCommonBuffer64:
ASSERT (MapInfo->PlainTextAddress == MapInfo->CryptedAddress);
CommonBufferHeader = (COMMON_BUFFER_HEADER *)(
(UINTN)MapInfo->PlainTextAddress - EFI_PAGE_SIZE
);
ASSERT (CommonBufferHeader->Signature == COMMON_BUFFER_SIG);
EncryptionTarget = CommonBufferHeader->StashBuffer;
//
// fall through
//
case EdkiiIoMmuOperationBusMasterWrite:
case EdkiiIoMmuOperationBusMasterWrite64:
CopyMem (
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
EncryptionTarget,
(VOID *) (UINTN) MapInfo->PlainTextAddress,
MapInfo->NumberOfBytes
);
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
break;
default:
//
// nothing to encrypt after BusMasterRead[64] operations
//
break;
}
//
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
// Restore the memory encryption mask on the area we used to hold the
// plaintext.
//
Status = MemEncryptSevSetPageEncMask (
0,
MapInfo->PlainTextAddress,
MapInfo->NumberOfPages,
TRUE
);
ASSERT_EFI_ERROR (Status);
if (EFI_ERROR (Status)) {
CpuDeadLoop ();
}
//
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
// For BusMasterCommonBuffer[64] operations, copy the stashed data to the
// original (now encrypted) location.
//
// For all other operations, fill the late bounce buffer (which existed as
// plaintext at some point) with zeros, and then release it (unless the UEFI
// memory map is locked).
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
//
if (MapInfo->Operation == EdkiiIoMmuOperationBusMasterCommonBuffer ||
MapInfo->Operation == EdkiiIoMmuOperationBusMasterCommonBuffer64) {
CopyMem (
(VOID *)(UINTN)MapInfo->CryptedAddress,
CommonBufferHeader->StashBuffer,
MapInfo->NumberOfBytes
);
} else {
ZeroMem (
(VOID *)(UINTN)MapInfo->PlainTextAddress,
EFI_PAGES_TO_SIZE (MapInfo->NumberOfPages)
);
if (!MemoryMapLocked) {
gBS->FreePages (MapInfo->PlainTextAddress, MapInfo->NumberOfPages);
}
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
}
OvmfPkg/IoMmuDxe: track all mappings The "mRecycledMapInfos" list implements an internal pool of unused MAP_INFO structures between the IoMmuUnmap() and IoMmuMap() functions. The original goal was to allow IoMmuUnmap() to tear down CommonBuffer mappings without releasing any memory: IoMmuUnmap() would recycle the MAP_INFO structure to the list, and IoMmuMap() would always check the list first, before allocating a brand new MAP_INFO structure. In one of the following patches, we'll change OvmfPkg/IoMmuDxe so that it unmaps all existent bus master operations (CommonBuffer, Read, Write) at ExitBootServices(), strictly after the individual device drivers abort pending DMA on the devices they manage, in their own ExitBootServices() notification functions. For this, rename and repurpose the list to track all live mappings. This means that IoMmuUnmap() will always release a MAP_INFO structure (even when cleaning up a CommonBuffer operation). That's fine (for now), because device drivers are no longer expected to call Unmap() in their ExitBootServices() notification functions. In theory, we could also move the allocation and freeing of the stash buffer from IoMmuAllocateBuffer() and IoMmuFreeBuffer(), respectively, to IoMmuMap() and IoMmuUnmap(). However, this would require allocating and freeing a stash buffer in *both* IoMmuMap() and IoMmuUnmap(), as IoMmuMap() performs in-place decryption for CommonBuffer operations, and IoMmuUnmap() performs in-place encryption for the same. By keeping the stash buffer allocation as-is, not only do we keep the code almost fully undisturbed, but - we also continue to guarantee that IoMmuUnmap() succeeds: allocating a stash buffer in IoMmuUnmap(), for in-place encryption after a CommonBuffer operation, could fail; - we also keep IoMmuUnmap() largely reusable for ExitBootServices() callback context: allocating a stash buffer in IoMmuUnmap() would simply be forbidden in that context. Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com>
2017-09-07 15:30:19 +02:00
//
// Forget the MAP_INFO structure, then free it (unless the UEFI memory map is
// locked).
OvmfPkg/IoMmuDxe: track all mappings The "mRecycledMapInfos" list implements an internal pool of unused MAP_INFO structures between the IoMmuUnmap() and IoMmuMap() functions. The original goal was to allow IoMmuUnmap() to tear down CommonBuffer mappings without releasing any memory: IoMmuUnmap() would recycle the MAP_INFO structure to the list, and IoMmuMap() would always check the list first, before allocating a brand new MAP_INFO structure. In one of the following patches, we'll change OvmfPkg/IoMmuDxe so that it unmaps all existent bus master operations (CommonBuffer, Read, Write) at ExitBootServices(), strictly after the individual device drivers abort pending DMA on the devices they manage, in their own ExitBootServices() notification functions. For this, rename and repurpose the list to track all live mappings. This means that IoMmuUnmap() will always release a MAP_INFO structure (even when cleaning up a CommonBuffer operation). That's fine (for now), because device drivers are no longer expected to call Unmap() in their ExitBootServices() notification functions. In theory, we could also move the allocation and freeing of the stash buffer from IoMmuAllocateBuffer() and IoMmuFreeBuffer(), respectively, to IoMmuMap() and IoMmuUnmap(). However, this would require allocating and freeing a stash buffer in *both* IoMmuMap() and IoMmuUnmap(), as IoMmuMap() performs in-place decryption for CommonBuffer operations, and IoMmuUnmap() performs in-place encryption for the same. By keeping the stash buffer allocation as-is, not only do we keep the code almost fully undisturbed, but - we also continue to guarantee that IoMmuUnmap() succeeds: allocating a stash buffer in IoMmuUnmap(), for in-place encryption after a CommonBuffer operation, could fail; - we also keep IoMmuUnmap() largely reusable for ExitBootServices() callback context: allocating a stash buffer in IoMmuUnmap() would simply be forbidden in that context. Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com>
2017-09-07 15:30:19 +02:00
//
RemoveEntryList (&MapInfo->Link);
if (!MemoryMapLocked) {
FreePool (MapInfo);
}
OvmfPkg/IoMmuDxe: track all mappings The "mRecycledMapInfos" list implements an internal pool of unused MAP_INFO structures between the IoMmuUnmap() and IoMmuMap() functions. The original goal was to allow IoMmuUnmap() to tear down CommonBuffer mappings without releasing any memory: IoMmuUnmap() would recycle the MAP_INFO structure to the list, and IoMmuMap() would always check the list first, before allocating a brand new MAP_INFO structure. In one of the following patches, we'll change OvmfPkg/IoMmuDxe so that it unmaps all existent bus master operations (CommonBuffer, Read, Write) at ExitBootServices(), strictly after the individual device drivers abort pending DMA on the devices they manage, in their own ExitBootServices() notification functions. For this, rename and repurpose the list to track all live mappings. This means that IoMmuUnmap() will always release a MAP_INFO structure (even when cleaning up a CommonBuffer operation). That's fine (for now), because device drivers are no longer expected to call Unmap() in their ExitBootServices() notification functions. In theory, we could also move the allocation and freeing of the stash buffer from IoMmuAllocateBuffer() and IoMmuFreeBuffer(), respectively, to IoMmuMap() and IoMmuUnmap(). However, this would require allocating and freeing a stash buffer in *both* IoMmuMap() and IoMmuUnmap(), as IoMmuMap() performs in-place decryption for CommonBuffer operations, and IoMmuUnmap() performs in-place encryption for the same. By keeping the stash buffer allocation as-is, not only do we keep the code almost fully undisturbed, but - we also continue to guarantee that IoMmuUnmap() succeeds: allocating a stash buffer in IoMmuUnmap(), for in-place encryption after a CommonBuffer operation, could fail; - we also keep IoMmuUnmap() largely reusable for ExitBootServices() callback context: allocating a stash buffer in IoMmuUnmap() would simply be forbidden in that context. Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com>
2017-09-07 15:30:19 +02:00
return EFI_SUCCESS;
}
/**
Completes the Map() operation and releases any corresponding resources.
@param This The protocol instance pointer.
@param Mapping The mapping value returned from Map().
@retval EFI_SUCCESS The range was unmapped.
@retval EFI_INVALID_PARAMETER Mapping is not a value that was returned by
Map().
@retval EFI_DEVICE_ERROR The data was not committed to the target system
memory.
**/
EFI_STATUS
EFIAPI
IoMmuUnmap (
IN EDKII_IOMMU_PROTOCOL *This,
IN VOID *Mapping
)
{
return IoMmuUnmapWorker (
This,
Mapping,
FALSE // MemoryMapLocked
);
}
/**
Allocates pages that are suitable for an OperationBusMasterCommonBuffer or
OperationBusMasterCommonBuffer64 mapping.
@param This The protocol instance pointer.
@param Type This parameter is not used and must be ignored.
@param MemoryType The type of memory to allocate,
EfiBootServicesData or EfiRuntimeServicesData.
@param Pages The number of pages to allocate.
@param HostAddress A pointer to store the base system memory
address of the allocated range.
@param Attributes The requested bit mask of attributes for the
allocated range.
@retval EFI_SUCCESS The requested memory pages were allocated.
@retval EFI_UNSUPPORTED Attributes is unsupported. The only legal
attribute bits are MEMORY_WRITE_COMBINE and
MEMORY_CACHED.
@retval EFI_INVALID_PARAMETER One or more parameters are invalid.
@retval EFI_OUT_OF_RESOURCES The memory pages could not be allocated.
**/
EFI_STATUS
EFIAPI
IoMmuAllocateBuffer (
IN EDKII_IOMMU_PROTOCOL *This,
IN EFI_ALLOCATE_TYPE Type,
IN EFI_MEMORY_TYPE MemoryType,
IN UINTN Pages,
IN OUT VOID **HostAddress,
IN UINT64 Attributes
)
{
EFI_STATUS Status;
EFI_PHYSICAL_ADDRESS PhysicalAddress;
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
VOID *StashBuffer;
UINTN CommonBufferPages;
COMMON_BUFFER_HEADER *CommonBufferHeader;
DEBUG ((
DEBUG_VERBOSE,
"%a: MemoryType=%u Pages=0x%Lx Attributes=0x%Lx\n",
__FUNCTION__,
(UINT32)MemoryType,
(UINT64)Pages,
Attributes
));
//
// Validate Attributes
//
if ((Attributes & EDKII_IOMMU_ATTRIBUTE_INVALID_FOR_ALLOCATE_BUFFER) != 0) {
return EFI_UNSUPPORTED;
}
//
// Check for invalid inputs
//
if (HostAddress == NULL) {
return EFI_INVALID_PARAMETER;
}
//
// The only valid memory types are EfiBootServicesData and
// EfiRuntimeServicesData
//
if (MemoryType != EfiBootServicesData &&
MemoryType != EfiRuntimeServicesData) {
return EFI_INVALID_PARAMETER;
}
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
//
// We'll need a header page for the COMMON_BUFFER_HEADER structure.
//
if (Pages > MAX_UINTN - 1) {
return EFI_OUT_OF_RESOURCES;
}
CommonBufferPages = Pages + 1;
//
// Allocate the stash in EfiBootServicesData type memory.
//
// Map() will temporarily save encrypted data in the stash for
// BusMasterCommonBuffer[64] operations, so the data can be decrypted to the
// original location.
//
// Unmap() will temporarily save plaintext data in the stash for
// BusMasterCommonBuffer[64] operations, so the data can be encrypted to the
// original location.
//
// StashBuffer always resides in encrypted memory.
//
StashBuffer = AllocatePages (Pages);
if (StashBuffer == NULL) {
return EFI_OUT_OF_RESOURCES;
}
PhysicalAddress = (UINTN)-1;
if ((Attributes & EDKII_IOMMU_ATTRIBUTE_DUAL_ADDRESS_CYCLE) == 0) {
//
// Limit allocations to memory below 4GB
//
PhysicalAddress = SIZE_4GB - 1;
}
Status = gBS->AllocatePages (
AllocateMaxAddress,
MemoryType,
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
CommonBufferPages,
&PhysicalAddress
);
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
if (EFI_ERROR (Status)) {
goto FreeStashBuffer;
}
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
CommonBufferHeader = (VOID *)(UINTN)PhysicalAddress;
PhysicalAddress += EFI_PAGE_SIZE;
CommonBufferHeader->Signature = COMMON_BUFFER_SIG;
CommonBufferHeader->StashBuffer = StashBuffer;
*HostAddress = (VOID *)(UINTN)PhysicalAddress;
DEBUG ((
DEBUG_VERBOSE,
"%a: Host=0x%Lx Stash=0x%p\n",
__FUNCTION__,
PhysicalAddress,
StashBuffer
));
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
return EFI_SUCCESS;
FreeStashBuffer:
FreePages (StashBuffer, Pages);
return Status;
}
/**
Frees memory that was allocated with AllocateBuffer().
@param This The protocol instance pointer.
@param Pages The number of pages to free.
@param HostAddress The base system memory address of the allocated
range.
@retval EFI_SUCCESS The requested memory pages were freed.
@retval EFI_INVALID_PARAMETER The memory range specified by HostAddress and
Pages was not allocated with AllocateBuffer().
**/
EFI_STATUS
EFIAPI
IoMmuFreeBuffer (
IN EDKII_IOMMU_PROTOCOL *This,
IN UINTN Pages,
IN VOID *HostAddress
)
{
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
UINTN CommonBufferPages;
COMMON_BUFFER_HEADER *CommonBufferHeader;
DEBUG ((
DEBUG_VERBOSE,
"%a: Host=0x%p Pages=0x%Lx\n",
__FUNCTION__,
HostAddress,
(UINT64)Pages
));
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
CommonBufferPages = Pages + 1;
CommonBufferHeader = (COMMON_BUFFER_HEADER *)(
(UINTN)HostAddress - EFI_PAGE_SIZE
);
//
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
// Check the signature.
//
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
ASSERT (CommonBufferHeader->Signature == COMMON_BUFFER_SIG);
if (CommonBufferHeader->Signature != COMMON_BUFFER_SIG) {
return EFI_INVALID_PARAMETER;
}
//
// Free the stash buffer. This buffer was always encrypted, so no need to
// zero it.
//
FreePages (CommonBufferHeader->StashBuffer, Pages);
OvmfPkg/IoMmuDxe: implement in-place decryption/encryption for Map/Unmap At the moment, we have the following distribution of actions between the IOMMU protocol member functions: - AllocateBuffer() allocates pages and clears the memory encryption mask. - FreeBuffer() re-sets the memory encryption mask, and deallocates pages. - Map() does nothing at all when BusMasterCommonBuffer[64] is requested (and AllocateBuffer() was called previously). Otherwise, Map() allocates pages, and clears the memory encryption mask. - Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64] operation. Otherwise, Unmap() clears the encryption mask, and frees the pages. This is wrong: the AllocateBuffer() protocol member is not expected to produce a buffer that is immediately usable, and client code is required to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the desired operation. Implement the right distribution of actions as follows: - AllocateBuffer() allocates pages and does not touch the encryption mask. - FreeBuffer() deallocates pages and does not touch the encryption mask. - Map() does not allocate pages when BusMasterCommonBuffer[64] is requested, and it allocates pages (bounce buffer) otherwise. Regardless of the BusMaster operation, Map() (and Map() only) clears the memory encryption mask. - Unmap() restores the encryption mask unconditionally. If the operation was BusMasterCommonBuffer[64], then Unmap() does not release the pages. Otherwise, the pages (bounce buffer) are released. This approach also ensures that Unmap() can be called from ExitBootServices() event handlers, for cleaning up BusMasterCommonBuffer[64] operations. (More specifically, for restoring the SEV encryption mask on any in-flight buffers, after resetting any referring devices.) ExitBootServices() event handlers must not change the UEFI memory map, thus any memory allocation or freeing in Unmap() would disqualify Unmap() from being called in such a context. Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation effectively means in-place decryption and encryption in a SEV context. As an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication Nr.24593 implies that we need a separate temporary buffer for decryption and encryption that will eventually land in-place. Allocating said temporary buffer in the straightforward way would violate the above allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer(). To completely rid Unmap() of dynamic memory impact, for BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of the MAP_INFO structures in a later patch. (The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically allocate memory internally for page splitting, however this won't happen in practice: in Unmap() we only restore the memory encryption mask, and don't genuinely set it. Any page splitting will have occurred in Map()'s MemEncryptSevClearPageEncMask() call first.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
2017-08-02 18:26:59 +02:00
//
// Release the common buffer itself. Unmap() has re-encrypted it in-place, so
// no need to zero it.
//
return gBS->FreePages ((UINTN)CommonBufferHeader, CommonBufferPages);
}
/**
Set IOMMU attribute for a system memory.
If the IOMMU protocol exists, the system memory cannot be used
for DMA by default.
When a device requests a DMA access for a system memory,
the device driver need use SetAttribute() to update the IOMMU
attribute to request DMA access (read and/or write).
The DeviceHandle is used to identify which device submits the request.
The IOMMU implementation need translate the device path to an IOMMU device
ID, and set IOMMU hardware register accordingly.
1) DeviceHandle can be a standard PCI device.
The memory for BusMasterRead need set EDKII_IOMMU_ACCESS_READ.
The memory for BusMasterWrite need set EDKII_IOMMU_ACCESS_WRITE.
The memory for BusMasterCommonBuffer need set
EDKII_IOMMU_ACCESS_READ|EDKII_IOMMU_ACCESS_WRITE.
After the memory is used, the memory need set 0 to keep it being
protected.
2) DeviceHandle can be an ACPI device (ISA, I2C, SPI, etc).
The memory for DMA access need set EDKII_IOMMU_ACCESS_READ and/or
EDKII_IOMMU_ACCESS_WRITE.
@param[in] This The protocol instance pointer.
@param[in] DeviceHandle The device who initiates the DMA access
request.
@param[in] Mapping The mapping value returned from Map().
@param[in] IoMmuAccess The IOMMU access.
@retval EFI_SUCCESS The IoMmuAccess is set for the memory range
specified by DeviceAddress and Length.
@retval EFI_INVALID_PARAMETER DeviceHandle is an invalid handle.
@retval EFI_INVALID_PARAMETER Mapping is not a value that was returned by
Map().
@retval EFI_INVALID_PARAMETER IoMmuAccess specified an illegal combination
of access.
@retval EFI_UNSUPPORTED DeviceHandle is unknown by the IOMMU.
@retval EFI_UNSUPPORTED The bit mask of IoMmuAccess is not supported
by the IOMMU.
@retval EFI_UNSUPPORTED The IOMMU does not support the memory range
specified by Mapping.
@retval EFI_OUT_OF_RESOURCES There are not enough resources available to
modify the IOMMU access.
@retval EFI_DEVICE_ERROR The IOMMU device reported an error while
attempting the operation.
**/
EFI_STATUS
EFIAPI
IoMmuSetAttribute (
IN EDKII_IOMMU_PROTOCOL *This,
IN EFI_HANDLE DeviceHandle,
IN VOID *Mapping,
IN UINT64 IoMmuAccess
)
{
return EFI_UNSUPPORTED;
}
EDKII_IOMMU_PROTOCOL mAmdSev = {
EDKII_IOMMU_PROTOCOL_REVISION,
IoMmuSetAttribute,
IoMmuMap,
IoMmuUnmap,
IoMmuAllocateBuffer,
IoMmuFreeBuffer,
};
OvmfPkg/IoMmuDxe: unmap all IOMMU mappings at ExitBootServices() Register an ExitBootServices() callback that tears down all IOMMU mappings, without modifying the UEFI memory map. The trick is that in the ExitBootServices() callback, we don't immediately do the work; instead we signal another (private) event. Normally the dispatch order of ExitBootServices() callbacks is unspecified (within the same task priority level anyway). By queueing another function, we delay the unmapping until after all PciIo and Virtio drivers abort -- in their own ExitBootServices() callbacks -- the pending DMA operations of their respective controllers. Furthermore, the fact that IoMmuUnmapWorker() rewrites client-owned memory when it unmaps a Write or CommonBuffer bus master operation, is safe even in this context. The existence of any given "MapInfo" in "mMapInfos" implies that the client buffer pointed-to by "MapInfo->CryptedAddress" was live when ExitBootServices() was entered. And, after entering ExitBootServices(), nothing must have changed the UEFI memory map, hence the client buffer at "MapInfo->CryptedAddress" still exists. Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com>
2017-09-07 18:02:54 +02:00
/**
Notification function that is queued when gBS->ExitBootServices() signals the
EFI_EVENT_GROUP_EXIT_BOOT_SERVICES event group. This function signals another
event, received as Context, and returns.
Signaling an event in this context is safe. The UEFI spec allows
gBS->SignalEvent() to return EFI_SUCCESS only; EFI_OUT_OF_RESOURCES is not
listed, hence memory is not allocated. The edk2 implementation also does not
release memory (and we only have to care about the edk2 implementation
because EDKII_IOMMU_PROTOCOL is edk2-specific anyway).
@param[in] Event Event whose notification function is being invoked.
Event is permitted to request the queueing of this
function at TPL_CALLBACK or TPL_NOTIFY task
priority level.
@param[in] EventToSignal Identifies the EFI_EVENT to signal. EventToSignal
is permitted to request the queueing of its
notification function only at TPL_CALLBACK level.
**/
STATIC
VOID
EFIAPI
AmdSevExitBoot (
IN EFI_EVENT Event,
IN VOID *EventToSignal
)
{
//
// (1) The NotifyFunctions of all the events in
// EFI_EVENT_GROUP_EXIT_BOOT_SERVICES will have been queued before
// AmdSevExitBoot() is entered.
//
// (2) AmdSevExitBoot() is executing minimally at TPL_CALLBACK.
//
// (3) AmdSevExitBoot() has been queued in unspecified order relative to the
// NotifyFunctions of all the other events in
// EFI_EVENT_GROUP_EXIT_BOOT_SERVICES whose NotifyTpl is the same as
// Event's.
//
// Consequences:
//
// - If Event's NotifyTpl is TPL_CALLBACK, then some other NotifyFunctions
// queued at TPL_CALLBACK may be invoked after AmdSevExitBoot() returns.
//
// - If Event's NotifyTpl is TPL_NOTIFY, then some other NotifyFunctions
// queued at TPL_NOTIFY may be invoked after AmdSevExitBoot() returns; plus
// *all* NotifyFunctions queued at TPL_CALLBACK will be invoked strictly
// after all NotifyFunctions queued at TPL_NOTIFY, including
// AmdSevExitBoot(), have been invoked.
//
// - By signaling EventToSignal here, whose NotifyTpl is TPL_CALLBACK, we
// queue EventToSignal's NotifyFunction after the NotifyFunctions of *all*
// events in EFI_EVENT_GROUP_EXIT_BOOT_SERVICES.
//
DEBUG ((DEBUG_VERBOSE, "%a\n", __FUNCTION__));
gBS->SignalEvent (EventToSignal);
}
/**
Notification function that is queued after the notification functions of all
events in the EFI_EVENT_GROUP_EXIT_BOOT_SERVICES event group. The same memory
map restrictions apply.
This function unmaps all currently existing IOMMU mappings.
@param[in] Event Event whose notification function is being invoked. Event
is permitted to request the queueing of this function
only at TPL_CALLBACK task priority level.
@param[in] Context Ignored.
**/
STATIC
VOID
EFIAPI
AmdSevUnmapAllMappings (
IN EFI_EVENT Event,
IN VOID *Context
)
{
LIST_ENTRY *Node;
LIST_ENTRY *NextNode;
MAP_INFO *MapInfo;
DEBUG ((DEBUG_VERBOSE, "%a\n", __FUNCTION__));
//
// All drivers that had set up IOMMU mappings have halted their respective
// controllers by now; tear down the mappings.
//
for (Node = GetFirstNode (&mMapInfos); Node != &mMapInfos; Node = NextNode) {
NextNode = GetNextNode (&mMapInfos, Node);
MapInfo = CR (Node, MAP_INFO, Link, MAP_INFO_SIG);
IoMmuUnmapWorker (
&mAmdSev, // This
MapInfo, // Mapping
TRUE // MemoryMapLocked
);
}
}
/**
Initialize Iommu Protocol.
**/
EFI_STATUS
EFIAPI
AmdSevInstallIoMmuProtocol (
VOID
)
{
EFI_STATUS Status;
OvmfPkg/IoMmuDxe: unmap all IOMMU mappings at ExitBootServices() Register an ExitBootServices() callback that tears down all IOMMU mappings, without modifying the UEFI memory map. The trick is that in the ExitBootServices() callback, we don't immediately do the work; instead we signal another (private) event. Normally the dispatch order of ExitBootServices() callbacks is unspecified (within the same task priority level anyway). By queueing another function, we delay the unmapping until after all PciIo and Virtio drivers abort -- in their own ExitBootServices() callbacks -- the pending DMA operations of their respective controllers. Furthermore, the fact that IoMmuUnmapWorker() rewrites client-owned memory when it unmaps a Write or CommonBuffer bus master operation, is safe even in this context. The existence of any given "MapInfo" in "mMapInfos" implies that the client buffer pointed-to by "MapInfo->CryptedAddress" was live when ExitBootServices() was entered. And, after entering ExitBootServices(), nothing must have changed the UEFI memory map, hence the client buffer at "MapInfo->CryptedAddress" still exists. Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com>
2017-09-07 18:02:54 +02:00
EFI_EVENT UnmapAllMappingsEvent;
EFI_EVENT ExitBootEvent;
EFI_HANDLE Handle;
OvmfPkg/IoMmuDxe: unmap all IOMMU mappings at ExitBootServices() Register an ExitBootServices() callback that tears down all IOMMU mappings, without modifying the UEFI memory map. The trick is that in the ExitBootServices() callback, we don't immediately do the work; instead we signal another (private) event. Normally the dispatch order of ExitBootServices() callbacks is unspecified (within the same task priority level anyway). By queueing another function, we delay the unmapping until after all PciIo and Virtio drivers abort -- in their own ExitBootServices() callbacks -- the pending DMA operations of their respective controllers. Furthermore, the fact that IoMmuUnmapWorker() rewrites client-owned memory when it unmaps a Write or CommonBuffer bus master operation, is safe even in this context. The existence of any given "MapInfo" in "mMapInfos" implies that the client buffer pointed-to by "MapInfo->CryptedAddress" was live when ExitBootServices() was entered. And, after entering ExitBootServices(), nothing must have changed the UEFI memory map, hence the client buffer at "MapInfo->CryptedAddress" still exists. Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com>
2017-09-07 18:02:54 +02:00
//
// Create the "late" event whose notification function will tear down all
// left-over IOMMU mappings.
//
Status = gBS->CreateEvent (
EVT_NOTIFY_SIGNAL, // Type
TPL_CALLBACK, // NotifyTpl
AmdSevUnmapAllMappings, // NotifyFunction
NULL, // NotifyContext
&UnmapAllMappingsEvent // Event
);
if (EFI_ERROR (Status)) {
return Status;
}
//
// Create the event whose notification function will be queued by
// gBS->ExitBootServices() and will signal the event created above.
//
Status = gBS->CreateEvent (
EVT_SIGNAL_EXIT_BOOT_SERVICES, // Type
TPL_CALLBACK, // NotifyTpl
AmdSevExitBoot, // NotifyFunction
UnmapAllMappingsEvent, // NotifyContext
&ExitBootEvent // Event
);
if (EFI_ERROR (Status)) {
goto CloseUnmapAllMappingsEvent;
}
Handle = NULL;
Status = gBS->InstallMultipleProtocolInterfaces (
&Handle,
&gEdkiiIoMmuProtocolGuid, &mAmdSev,
NULL
);
OvmfPkg/IoMmuDxe: unmap all IOMMU mappings at ExitBootServices() Register an ExitBootServices() callback that tears down all IOMMU mappings, without modifying the UEFI memory map. The trick is that in the ExitBootServices() callback, we don't immediately do the work; instead we signal another (private) event. Normally the dispatch order of ExitBootServices() callbacks is unspecified (within the same task priority level anyway). By queueing another function, we delay the unmapping until after all PciIo and Virtio drivers abort -- in their own ExitBootServices() callbacks -- the pending DMA operations of their respective controllers. Furthermore, the fact that IoMmuUnmapWorker() rewrites client-owned memory when it unmaps a Write or CommonBuffer bus master operation, is safe even in this context. The existence of any given "MapInfo" in "mMapInfos" implies that the client buffer pointed-to by "MapInfo->CryptedAddress" was live when ExitBootServices() was entered. And, after entering ExitBootServices(), nothing must have changed the UEFI memory map, hence the client buffer at "MapInfo->CryptedAddress" still exists. Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com>
2017-09-07 18:02:54 +02:00
if (EFI_ERROR (Status)) {
goto CloseExitBootEvent;
}
return EFI_SUCCESS;
CloseExitBootEvent:
gBS->CloseEvent (ExitBootEvent);
CloseUnmapAllMappingsEvent:
gBS->CloseEvent (UnmapAllMappingsEvent);
return Status;
}