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OvmfPkg/ResetVector: Save the encryption mask at boot time

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BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3108

The early assembler code performs validation for some of the SEV-related
information, specifically the encryption bit position. To avoid having to
re-validate the encryption bit position as the system proceeds through its
boot phases, save the validated encryption bit position in the SEV-ES work
area for use by later phases.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <2609724859cf21f0c6d45bc323e94465dca4e621.1610045305.git.thomas.lendacky@amd.com>
This commit is contained in:
Tom Lendacky 2021-01-07 12:48:15 -06:00 committed by mergify[bot]
parent bd0c1c8e22
commit 3b32be7e71
3 changed files with 12 additions and 1 deletions
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2
OvmfPkg/Include/Library/MemEncryptSevLib.h
View File

@ -29,6 +29,8 @@ typedef struct _SEC_SEV_ES_WORK_AREA {
UINT8 Reserved1[7]; UINT8 Reserved1[7];
UINT64 RandomData; UINT64 RandomData;
UINT64 EncryptionMask;
} SEC_SEV_ES_WORK_AREA; } SEC_SEV_ES_WORK_AREA;
/** /**

10
OvmfPkg/ResetVector/Ia32/PageTables64.asm
View File

@ -145,7 +145,7 @@ GetSevEncBit:
; The encryption bit position is always above 31 ; The encryption bit position is always above 31
sub ebx, 32 sub ebx, 32
jns SevExit jns SevSaveMask
; Encryption bit was reported as 31 or below, enter a HLT loop ; Encryption bit was reported as 31 or below, enter a HLT loop
SevEncBitLowHlt: SevEncBitLowHlt:
@ -153,6 +153,14 @@ SevEncBitLowHlt:
hlt hlt
jmp SevEncBitLowHlt jmp SevEncBitLowHlt
SevSaveMask:
xor edx, edx
bts edx, ebx
mov dword[SEV_ES_WORK_AREA_ENC_MASK], 0
mov dword[SEV_ES_WORK_AREA_ENC_MASK + 4], edx
jmp SevExit
NoSev: NoSev:
; ;
; Perform an SEV-ES sanity check by seeing if a #VC exception occurred. ; Perform an SEV-ES sanity check by seeing if a #VC exception occurred.

1
OvmfPkg/ResetVector/ResetVector.nasmb
View File

@ -74,6 +74,7 @@
%define GHCB_SIZE (FixedPcdGet32 (PcdOvmfSecGhcbSize)) %define GHCB_SIZE (FixedPcdGet32 (PcdOvmfSecGhcbSize))
%define SEV_ES_WORK_AREA (FixedPcdGet32 (PcdSevEsWorkAreaBase)) %define SEV_ES_WORK_AREA (FixedPcdGet32 (PcdSevEsWorkAreaBase))
%define SEV_ES_WORK_AREA_RDRAND (FixedPcdGet32 (PcdSevEsWorkAreaBase) + 8) %define SEV_ES_WORK_AREA_RDRAND (FixedPcdGet32 (PcdSevEsWorkAreaBase) + 8)
%define SEV_ES_WORK_AREA_ENC_MASK (FixedPcdGet32 (PcdSevEsWorkAreaBase) + 16)
%define SEV_ES_VC_TOP_OF_STACK (FixedPcdGet32 (PcdOvmfSecPeiTempRamBase) + FixedPcdGet32 (PcdOvmfSecPeiTempRamSize)) %define SEV_ES_VC_TOP_OF_STACK (FixedPcdGet32 (PcdOvmfSecPeiTempRamBase) + FixedPcdGet32 (PcdOvmfSecPeiTempRamSize))
%include "Ia32/Flat32ToFlat64.asm" %include "Ia32/Flat32ToFlat64.asm"
%include "Ia32/PageTables64.asm" %include "Ia32/PageTables64.asm"