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OvmfPkg: Realize EfiMemoryAcceptProtocol in AmdSevDxe

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When a guest OS does not support unaccepted memory, the unaccepted
memory must be accepted before returning a memory map to the caller.

EfiMemoryAcceptProtocol is defined in MdePkg and is implemented /
Installed in AmdSevDxe for AMD SEV-SNP memory acceptance.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Acked-by: Jiewen Yao <Jiewen.yao@intel.com>
Signed-off-by: Dionna Glaze <dionnaglaze@google.com>
Message-Id: <20221108164616.3251967-2-dionnaglaze@google.com>
This commit is contained in:
Sophia Wolf 2022-11-08 16:46:14 +00:00 committed by mergify[bot]
parent e5ec3ba409
commit 59aa48bb7d
3 changed files with 74 additions and 8 deletions
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49
OvmfPkg/AmdSevDxe/AmdSevDxe.c
View File

@ -20,6 +20,7 @@
#include <Library/UefiBootServicesTableLib.h>
#include <Guid/ConfidentialComputingSevSnpBlob.h>
#include <Library/PcdLib.h>
#include <Protocol/MemoryAccept.h>
STATIC CONFIDENTIAL_COMPUTING_SNP_BLOB_LOCATION mSnpBootDxeTable = {
SIGNATURE_32 ('A', 'M', 'D', 'E'),
@ -31,6 +32,40 @@ STATIC CONFIDENTIAL_COMPUTING_SNP_BLOB_LOCATION mSnpBootDxeTable = {
FixedPcdGet32 (PcdOvmfCpuidSize),
};
STATIC EFI_HANDLE mAmdSevDxeHandle = NULL;
#define IS_ALIGNED(x, y) ((((x) & ((y) - 1)) == 0))
STATIC
EFI_STATUS
EFIAPI
AmdSevMemoryAccept (
IN EDKII_MEMORY_ACCEPT_PROTOCOL *This,
IN EFI_PHYSICAL_ADDRESS StartAddress,
IN UINTN Size
)
{
//
// The StartAddress must be page-aligned, and the Size must be a positive
// multiple of SIZE_4KB. Use an assert instead of returning an erros since
// this is an EDK2-internal protocol.
//
ASSERT (IS_ALIGNED (StartAddress, SIZE_4KB));
ASSERT (IS_ALIGNED (Size, SIZE_4KB));
ASSERT (Size != 0);
MemEncryptSevSnpPreValidateSystemRam (
StartAddress,
EFI_SIZE_TO_PAGES (Size)
);
return EFI_SUCCESS;
}
STATIC EDKII_MEMORY_ACCEPT_PROTOCOL mMemoryAcceptProtocol = {
AmdSevMemoryAccept
};
EFI_STATUS
EFIAPI
AmdSevDxeEntryPoint (
@ -147,11 +182,23 @@ AmdSevDxeEntryPoint (
}
}
if (MemEncryptSevSnpIsEnabled ()) {
//
// Memory acceptance began being required in SEV-SNP, so install the
// memory accept protocol implementation for a SEV-SNP active guest.
//
Status = gBS->InstallProtocolInterface (
&mAmdSevDxeHandle,
&gEdkiiMemoryAcceptProtocolGuid,
EFI_NATIVE_INTERFACE,
&mMemoryAcceptProtocol
);
ASSERT_EFI_ERROR (Status);
//
// If its SEV-SNP active guest then install the CONFIDENTIAL_COMPUTING_SEV_SNP_BLOB.
// It contains the location for both the Secrets and CPUID page.
//
if (MemEncryptSevSnpIsEnabled ()) {
return gBS->InstallConfigurationTable (
&gConfidentialComputingSevSnpBlobGuid,
&mSnpBootDxeTable

3
OvmfPkg/AmdSevDxe/AmdSevDxe.inf
View File

@ -47,6 +47,9 @@
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsBase
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsSize
[Protocols]
gEdkiiMemoryAcceptProtocolGuid
[Guids]
gConfidentialComputingSevSnpBlobGuid

22
OvmfPkg/Library/BaseMemEncryptSevLib/X64/DxeSnpSystemRamValidate.c
View File

@ -14,6 +14,7 @@
#include <Library/MemEncryptSevLib.h>
#include "SnpPageStateChange.h"
#include "VirtualMemory.h"
/**
Pre-validate the system RAM when SEV-SNP is enabled in the guest VM.
@ -29,12 +30,27 @@ MemEncryptSevSnpPreValidateSystemRam (
IN UINTN NumPages
)
{
EFI_STATUS Status;
if (!MemEncryptSevSnpIsEnabled ()) {
return;
}
//
// All the pre-validation must be completed in the PEI phase.
//
// DXE pre-validation may happen with the memory accept protocol.
// The protocol should only be called outside the prevalidated ranges
// that the PEI stage code explicitly skips. Specifically, only memory
// ranges that are classified as unaccepted.
if (BaseAddress >= SIZE_4GB) {
Status = InternalMemEncryptSevCreateIdentityMap1G (
0,
BaseAddress,
EFI_PAGES_TO_SIZE (NumPages)
);
if (EFI_ERROR (Status)) {
ASSERT (FALSE);
CpuDeadLoop ();
}
}
InternalSetPageState (BaseAddress, NumPages, SevSnpPagePrivate, TRUE);
}