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OvmfPkg: Add AmdSevDxe driver 

When SEV is enabled, the MMIO memory range must be mapped as unencrypted
(i.e C-bit cleared).

We need to clear the C-bit for MMIO GCD entries in order to cover the
ranges that were added during the PEI phase (through memory resource
descriptor HOBs). Additionally, the NonExistent ranges are processed
in order to cover, in advance, MMIO ranges added later in the DXE phase
by various device drivers, via the appropriate DXE memory space services.

The approach is not transparent for later addition of system memory ranges
to the GCD memory space map. (Such ranges should be encrypted.) OVMF does
not do such a thing at the moment, so this approach should be OK.

The driver is being added to the APRIORI DXE file so that, we clear the
C-bit from MMIO regions before any driver accesses it.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Leo Duran <leo.duran@amd.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Suggested-by: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Jordan Justen <jordan.l.justen@intel.com>
This commit is contained in:
Brijesh Singh 2017-07-06 09:26:45 -04:00 committed by Jordan Justen
parent 13b5d743c8
commit 24e4ad7554
6 changed files with 124 additions and 0 deletions
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75
OvmfPkg/AmdSevDxe/AmdSevDxe.c Normal file
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@ -0,0 +1,75 @@
/** @file
AMD Sev Dxe driver. This driver is dispatched early in DXE, due to being list
in APRIORI. It clears C-bit from MMIO and NonExistent Memory space when SEV is
enabled.
Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD
License which accompanies this distribution. The full text of the license may
be found at http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
**/
#include <PiDxe.h>
#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/DxeServicesTableLib.h>
#include <Library/MemEncryptSevLib.h>
EFI_STATUS
EFIAPI
AmdSevDxeEntryPoint (
IN EFI_HANDLE ImageHandle,
IN EFI_SYSTEM_TABLE *SystemTable
)
{
EFI_STATUS Status;
EFI_GCD_MEMORY_SPACE_DESCRIPTOR *AllDescMap;
UINTN NumEntries;
UINTN Index;
//
// Do nothing when SEV is not enabled
//
if (!MemEncryptSevIsEnabled ()) {
return EFI_UNSUPPORTED;
}
//
// Iterate through the GCD map and clear the C-bit from MMIO and NonExistent
// memory space. The NonExistent memory space will be used for mapping the MMIO
// space added later (eg PciRootBridge). By clearing both known MMIO and
// NonExistent memory space can gurantee that current and furture MMIO adds
// will have C-bit cleared.
//
Status = gDS->GetMemorySpaceMap (&NumEntries, &AllDescMap);
if (!EFI_ERROR (Status)) {
for (Index = 0; Index < NumEntries; Index++) {
CONST EFI_GCD_MEMORY_SPACE_DESCRIPTOR *Desc;
Desc = &AllDescMap[Index];
if (Desc->GcdMemoryType == EfiGcdMemoryTypeMemoryMappedIo ||
Desc->GcdMemoryType == EfiGcdMemoryTypeNonExistent) {
Status = MemEncryptSevClearPageEncMask (0,
Desc->BaseAddress,
EFI_SIZE_TO_PAGES(Desc->Length),
FALSE);
ASSERT_EFI_ERROR (Status);
}
}
FreePool (AllDescMap);
}
return EFI_SUCCESS;
}

43
OvmfPkg/AmdSevDxe/AmdSevDxe.inf Normal file
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@ -0,0 +1,43 @@
#/** @file
#
# Driver clears the encryption attribute from MMIO regions when SEV is enabled
#
# Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
#
# This program and the accompanying materials
# are licensed and made available under the terms and conditions of the BSD
# License which accompanies this distribution. The full text of the license may
# be found at http://opensource.org/licenses/bsd-license.php
#
# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
#
#**/
[Defines]
INF_VERSION = 1.25
BASE_NAME = AmdSevDxe
FILE_GUID = 2ec9da37-ee35-4de9-86c5-6d9a81dc38a7
MODULE_TYPE = DXE_DRIVER
VERSION_STRING = 1.0
ENTRY_POINT = AmdSevDxeEntryPoint
[Sources]
AmdSevDxe.c
[Packages]
MdePkg/MdePkg.dec
MdeModulePkg/MdeModulePkg.dec
OvmfPkg/OvmfPkg.dec
[LibraryClasses]
BaseLib
UefiLib
UefiDriverEntryPoint
UefiBootServicesTableLib
DxeServicesTableLib
DebugLib
MemEncryptSevLib
[Depex]
TRUE

1
OvmfPkg/OvmfPkgIa32X64.dsc
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@ -825,6 +825,7 @@
!endif
OvmfPkg/PlatformDxe/Platform.inf
OvmfPkg/AmdSevDxe/AmdSevDxe.inf
!if $(SMM_REQUIRE) == TRUE
OvmfPkg/SmmAccess/SmmAccess2Dxe.inf

2
OvmfPkg/OvmfPkgIa32X64.fdf
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@ -191,6 +191,7 @@ READ_LOCK_STATUS = TRUE
APRIORI DXE {
INF MdeModulePkg/Universal/DevicePathDxe/DevicePathDxe.inf
INF MdeModulePkg/Universal/PCD/Dxe/Pcd.inf
INF OvmfPkg/AmdSevDxe/AmdSevDxe.inf
!if $(SMM_REQUIRE) == FALSE
INF OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf
!endif
@ -352,6 +353,7 @@ INF RuleOverride=CSM OvmfPkg/Csm/Csm16/Csm16.inf
INF OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
INF OvmfPkg/VirtioGpuDxe/VirtioGpu.inf
INF OvmfPkg/PlatformDxe/Platform.inf
INF OvmfPkg/AmdSevDxe/AmdSevDxe.inf
!if $(SMM_REQUIRE) == TRUE
INF OvmfPkg/SmmAccess/SmmAccess2Dxe.inf

1
OvmfPkg/OvmfPkgX64.dsc
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@ -823,6 +823,7 @@
!endif
OvmfPkg/PlatformDxe/Platform.inf
OvmfPkg/AmdSevDxe/AmdSevDxe.inf
!if $(SMM_REQUIRE) == TRUE
OvmfPkg/SmmAccess/SmmAccess2Dxe.inf

2
OvmfPkg/OvmfPkgX64.fdf
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@ -191,6 +191,7 @@ READ_LOCK_STATUS = TRUE
APRIORI DXE {
INF MdeModulePkg/Universal/DevicePathDxe/DevicePathDxe.inf
INF MdeModulePkg/Universal/PCD/Dxe/Pcd.inf
INF OvmfPkg/AmdSevDxe/AmdSevDxe.inf
!if $(SMM_REQUIRE) == FALSE
INF OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf
!endif
@ -352,6 +353,7 @@ INF RuleOverride=CSM OvmfPkg/Csm/Csm16/Csm16.inf
INF OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
INF OvmfPkg/VirtioGpuDxe/VirtioGpu.inf
INF OvmfPkg/PlatformDxe/Platform.inf
INF OvmfPkg/AmdSevDxe/AmdSevDxe.inf
!if $(SMM_REQUIRE) == TRUE
INF OvmfPkg/SmmAccess/SmmAccess2Dxe.inf