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OvmfPkg/ResetVector: Fix SNP CPUID table processing results for ECX/EDX

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The current support within the boot SNP CPUID table processing mistakenly
swaps the ECX and EDX results. It does not have an effect at this time
because current CPUID results checking does not check ECX or EDX. However,
any future CPUID checks that need to check ECX or EDX may have erroneous
behavior.

Fix the assembler code to save ECX and EDX to the proper locations.

Fixes: 34819f2caccb ("OvmfPkg/ResetVector: use SEV-SNP-validated CPUID values")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Michael Roth <michael.roth@amd.com>
This commit is contained in:
Tom Lendacky 2024-02-02 13:18:37 -06:00 committed by mergify[bot]
parent a1b98c8f84
commit cd6f215223
1 changed files with 2 additions and 2 deletions

4
OvmfPkg/ResetVector/Ia32/AmdSev.asm

@ -395,9 +395,9 @@ SnpCpuidEntryFound:
mov [esp + VC_CPUID_RESULT_EAX], eax
mov eax, [ecx + SNP_CPUID_ENTRY_EBX]
mov [esp + VC_CPUID_RESULT_EBX], eax
mov eax, [ecx + SNP_CPUID_ENTRY_EDX]
mov [esp + VC_CPUID_RESULT_ECX], eax
mov eax, [ecx + SNP_CPUID_ENTRY_ECX]
mov [esp + VC_CPUID_RESULT_ECX], eax
mov eax, [ecx + SNP_CPUID_ENTRY_EDX]
mov [esp + VC_CPUID_RESULT_EDX], eax
jmp VmmDoneSnpCpuid