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OvmfPkg/SecMain: validate the memory used for decompressing Fv 

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275

The VMM launch sequence should have pre-validated all the data pages used
in the Reset vector. The range does not cover the data pages used during
the SEC phase (mainly PEI and DXE firmware volume decompression memory).

When SEV-SNP is active, the memory must be pre-validated before the access.
Add support to pre-validate the memory range from SnpSecPreValidatedStart
to SnpSecPreValidatedEnd. This should be sufficent to enter into the PEI
phase.

Cc: Michael Roth <michael.roth@amd.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Jiewen Yao <Jiewen.yao@intel.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
This commit is contained in:
Brijesh Singh 2021-12-09 11:27:46 +08:00 committed by mergify[bot]
parent d39f8d88ec
commit 202fb22be6
8 changed files with 68 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
OvmfPkg/FvmainCompactScratchEnd.fdf.inc
View File

@ -63,3 +63,8 @@ DEFINE DECOMP_SCRATCH_BASE_MASK = 0xFFF00000
DEFINE DECOMP_SCRATCH_BASE = (($(DECOMP_SCRATCH_BASE_UNALIGNED) + $(DECOMP_SCRATCH_BASE_ALIGNMENT)) & $(DECOMP_SCRATCH_BASE_MASK))
SET gUefiOvmfPkgTokenSpaceGuid.PcdOvmfDecompressionScratchEnd = $(DECOMP_SCRATCH_BASE) + $(DECOMP_SCRATCH_SIZE)
#
# The range of pages that should be pre-validated during the SEC phase when SEV-SNP is active in the guest VM.
SET gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedStart = $(MEMFD_BASE_ADDRESS) + gUefiOvmfPkgTokenSpaceGuid.PcdOvmfPeiMemFvBase
SET gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedEnd = $(DECOMP_SCRATCH_BASE) + $(DECOMP_SCRATCH_SIZE)

2
OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
View File

@ -60,3 +60,5 @@
gUefiCpuPkgTokenSpaceGuid.PcdSevEsWorkAreaBase
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfPeiMemFvBase
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesBase
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedEnd
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedStart

5
OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c
View File

@ -29,6 +29,11 @@ STATIC SNP_PRE_VALIDATED_RANGE mPreValidatedRange[] = {
FixedPcdGet32 (PcdOvmfSecPageTablesBase),
FixedPcdGet32 (PcdOvmfPeiMemFvBase),
},
// The below range is pre-validated by the Sec/SecMain.c
{
FixedPcdGet32 (PcdOvmfSecValidatedStart),
FixedPcdGet32 (PcdOvmfSecValidatedEnd)
},
};
STATIC

4
OvmfPkg/OvmfPkg.dec
View File

@ -364,6 +364,10 @@
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidBase|0|UINT32|0x60
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidSize|0|UINT32|0x61
## The range of memory that is validated by the SEC phase.
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedStart|0|UINT32|0x62
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedEnd|0|UINT32|0x63
[PcdsDynamic, PcdsDynamicEx]
gUefiOvmfPkgTokenSpaceGuid.PcdEmuVariableEvent|0|UINT64|2
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFlashVariablesEnable|FALSE|BOOLEAN|0x10

22
OvmfPkg/Sec/AmdSev.c
View File

@ -55,7 +55,6 @@ SevEsProtocolFailure (
@retval FALSE SEV-SNP is not enabled
**/
STATIC
BOOLEAN
SevSnpIsEnabled (
VOID
@ -281,3 +280,24 @@ SevEsIsEnabled (
return (SevEsWorkArea->SevEsEnabled != 0);
}
/**
Validate System RAM used for decompressing the PEI and DXE firmware volumes
when SEV-SNP is active. The PCDs SecValidatedStart and SecValidatedEnd are
set in OvmfPkg/FvmainCompactScratchEnd.fdf.inc.
**/
VOID
SecValidateSystemRam (
VOID
)
{
PHYSICAL_ADDRESS Start, End;
if (IsSevGuest () && SevSnpIsEnabled ()) {
Start = (EFI_PHYSICAL_ADDRESS)(UINTN)PcdGet32 (PcdOvmfSecValidatedStart);
End = (EFI_PHYSICAL_ADDRESS)(UINTN)PcdGet32 (PcdOvmfSecValidatedEnd);
MemEncryptSevSnpPreValidateSystemRam (Start, EFI_SIZE_TO_PAGES ((UINTN)(End - Start)));
}
}

23
OvmfPkg/Sec/AmdSev.h
View File

@ -68,4 +68,27 @@ SevEsIsEnabled (
VOID
);
/**
Validate System RAM used for decompressing the PEI and DXE firmware volumes
when SEV-SNP is active. The PCDs SecValidatedStart and SecValidatedEnd are
set in OvmfPkg/FvmainCompactScratchEnd.fdf.inc.
**/
VOID
SecValidateSystemRam (
VOID
);
/**
Determine if SEV-SNP is active.
@retval TRUE SEV-SNP is enabled
@retval FALSE SEV-SNP is not enabled
**/
BOOLEAN
SevSnpIsEnabled (
VOID
);
#endif

5
OvmfPkg/Sec/SecMain.c
View File

@ -860,6 +860,11 @@ SecCoreStartupWithStack (
SecCoreData.BootFirmwareVolumeBase = BootFv;
SecCoreData.BootFirmwareVolumeSize = (UINTN)BootFv->FvLength;
//
// Validate the System RAM used in the SEC Phase
//
SecValidateSystemRam ();
//
// Make sure the 8259 is masked before initializing the Debug Agent and the debug timer is enabled
//

3
OvmfPkg/Sec/SecMain.inf
View File

@ -52,6 +52,7 @@
PeCoffExtraActionLib
ExtractGuidedSectionLib
LocalApicLib
MemEncryptSevLib
CpuExceptionHandlerLib
[Ppis]
@ -74,6 +75,8 @@
gEfiMdeModulePkgTokenSpaceGuid.PcdInitValueInTempStack
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfConfidentialComputingWorkAreaHeader
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaBase
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedStart
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedEnd
[FeaturePcd]
gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire