On Fri, 14 Jul 2023 at 22:28, Tom Lendacky <thomas.lenda...@amd.com> wrote:
>
> Commit 63c50d3ff2854a76432b752af4f2a76f33ff1974 changed the check that is
> used to determine if SEV-ES is active. Originally, a CMP instruction with
> a supporting JZ instruction was used for the check. It was changed to use
> the BT instruction but not JZ instruction. The result of a BT instruction
> changes the the carry flag (CF) and not the zero flag (ZF). As a result,
> the wrong condition is being checked. Update the JZ to a JNC to properly
> detect if SEV-ES is active.
>
> Fixes: 63c50d3ff285 ("OvmfPkg/ResetVector: cache the SEV status MSR...")
> Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
> ---
> OvmfPkg/ResetVector/Ia32/Flat32ToFlat64.asm | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/OvmfPkg/ResetVector/Ia32/Flat32ToFlat64.asm
> b/OvmfPkg/ResetVector/Ia32/Flat32ToFlat64.asm
> index c5c683ebed3e..429a58c5efd3 100644
> --- a/OvmfPkg/ResetVector/Ia32/Flat32ToFlat64.asm
> +++ b/OvmfPkg/ResetVector/Ia32/Flat32ToFlat64.asm
> @@ -44,7 +44,7 @@ Transition32FlatTo64Flat:
>
> mov ecx, 1
> bt [SEV_ES_WORK_AREA_STATUS_MSR], ecx
> - jz EnablePaging
> + jnc EnablePaging
>
> ;
> ; SEV-ES is active, perform a quick sanity check against the reported
Merged as #4646
Thanks,
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