Re: [PATCH v4 1/2] x86/cpufeatures: Add "Allowed SEV Features" Feature

["Gupta, Pankaj" <pankaj.gupta@amd.com>]

On 3/6/2025 1:38 AM, Kim Phillips wrote:
> From: Kishon Vijay Abraham I <kvijayab@amd.com>
> 
> Add CPU feature detection for "Allowed SEV Features" to allow the
> Hypervisor to enforce that SEV-ES and SEV-SNP guest VMs cannot
> enable features (via SEV_FEATURES) that the Hypervisor does not
> support or wish to be enabled.
> 
> Signed-off-by: Kishon Vijay Abraham I <kvijayab@amd.com>
> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
> Signed-off-by: Kim Phillips <kim.phillips@amd.com>

Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>

> ---
>   arch/x86/include/asm/cpufeatures.h | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> index 8f8aaf94dc00..6a12c8c48bd2 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -454,6 +454,7 @@
>   #define X86_FEATURE_DEBUG_SWAP		(19*32+14) /* "debug_swap" SEV-ES full debug state swap support */
>   #define X86_FEATURE_RMPREAD		(19*32+21) /* RMPREAD instruction */
>   #define X86_FEATURE_SEGMENTED_RMP	(19*32+23) /* Segmented RMP support */
> +#define X86_FEATURE_ALLOWED_SEV_FEATURES (19*32+27) /* Allowed SEV Features */
>   #define X86_FEATURE_SVSM		(19*32+28) /* "svsm" SVSM present */
>   #define X86_FEATURE_HV_INUSE_WR_ALLOWED	(19*32+30) /* Allow Write to in-use hypervisor-owned pages */
>