From 202fb22be6e9100c2ce6329f1b09f885dfdb514a Mon Sep 17 00:00:00 2001 From: Brijesh Singh Date: Thu, 9 Dec 2021 11:27:46 +0800 Subject: [PATCH] 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 Cc: James Bottomley Cc: Min Xu Cc: Jiewen Yao Cc: Tom Lendacky Cc: Jordan Justen Cc: Ard Biesheuvel Cc: Erdem Aktas Cc: Gerd Hoffmann Acked-by: Jiewen Yao Acked-by: Gerd Hoffmann Signed-off-by: Brijesh Singh --- OvmfPkg/FvmainCompactScratchEnd.fdf.inc | 5 ++++ .../PeiMemEncryptSevLib.inf | 2 ++ .../X64/PeiSnpSystemRamValidate.c | 5 ++++ OvmfPkg/OvmfPkg.dec | 4 ++++ OvmfPkg/Sec/AmdSev.c | 22 +++++++++++++++++- OvmfPkg/Sec/AmdSev.h | 23 +++++++++++++++++++ OvmfPkg/Sec/SecMain.c | 5 ++++ OvmfPkg/Sec/SecMain.inf | 3 +++ 8 files changed, 68 insertions(+), 1 deletion(-) diff --git a/OvmfPkg/FvmainCompactScratchEnd.fdf.inc b/OvmfPkg/FvmainCompactScratchEnd.fdf.inc index 46f5258329..d8d45fc9aa 100644 --- a/OvmfPkg/FvmainCompactScratchEnd.fdf.inc +++ b/OvmfPkg/FvmainCompactScratchEnd.fdf.inc @@ -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) diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf index 49d5bd1bef..50c83859d7 100644 --- a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf +++ b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf @@ -60,3 +60,5 @@ gUefiCpuPkgTokenSpaceGuid.PcdSevEsWorkAreaBase gUefiOvmfPkgTokenSpaceGuid.PcdOvmfPeiMemFvBase gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesBase + gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedEnd + gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedStart diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c index 0e3eba3c51..4970165444 100644 --- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c +++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c @@ -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 diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec index bc14cf2ed4..c22b846cd6 100644 --- a/OvmfPkg/OvmfPkg.dec +++ b/OvmfPkg/OvmfPkg.dec @@ -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 diff --git a/OvmfPkg/Sec/AmdSev.c b/OvmfPkg/Sec/AmdSev.c index aa655fd9cb..499d0c27d8 100644 --- a/OvmfPkg/Sec/AmdSev.c +++ b/OvmfPkg/Sec/AmdSev.c @@ -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))); + } +} diff --git a/OvmfPkg/Sec/AmdSev.h b/OvmfPkg/Sec/AmdSev.h index c0b1ca9618..dffd2ceb96 100644 --- a/OvmfPkg/Sec/AmdSev.h +++ b/OvmfPkg/Sec/AmdSev.h @@ -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 diff --git a/OvmfPkg/Sec/SecMain.c b/OvmfPkg/Sec/SecMain.c index 58e3b923b4..2c5561661e 100644 --- a/OvmfPkg/Sec/SecMain.c +++ b/OvmfPkg/Sec/SecMain.c @@ -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 // diff --git a/OvmfPkg/Sec/SecMain.inf b/OvmfPkg/Sec/SecMain.inf index 41dcdba120..95cf0025e1 100644 --- a/OvmfPkg/Sec/SecMain.inf +++ b/OvmfPkg/Sec/SecMain.inf @@ -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 -- 2.39.2