Re: [PATCH 1/1] x86/kvm/svm: Implement support for PSFD

[Tom Lendacky]

On 4/7/21 2:45 PM, Ramakrishna Saripalli wrote:
> From: Ramakrishna Saripalli <rk.saripalli@xxxxxxx>
> 
> Expose Predictive Store Forwarding capability to guests.
> Guests enable or disable PSF via SPEC_CTRL MSR.
> 
> Signed-off-by: Ramakrishna Saripalli <rk.saripalli@xxxxxxx>
> ---
>  arch/x86/kvm/cpuid.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 6bd2f8b830e4..9c4af0fef6d7 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -448,6 +448,8 @@ void kvm_set_cpu_caps(void)
>  		kvm_cpu_cap_set(X86_FEATURE_INTEL_STIBP);
>  	if (boot_cpu_has(X86_FEATURE_AMD_SSBD))
>  		kvm_cpu_cap_set(X86_FEATURE_SPEC_CTRL_SSBD);
> +	if (boot_cpu_has(X86_FEATURE_AMD_PSFD))
> +		kvm_cpu_cap_set(X86_FEATURE_AMD_PSFD);
>  
>  	kvm_cpu_cap_mask(CPUID_7_1_EAX,
>  		F(AVX_VNNI) | F(AVX512_BF16)
> @@ -482,7 +484,7 @@ void kvm_set_cpu_caps(void)
>  	kvm_cpu_cap_mask(CPUID_8000_0008_EBX,
>  		F(CLZERO) | F(XSAVEERPTR) |
>  		F(WBNOINVD) | F(AMD_IBPB) | F(AMD_IBRS) | F(AMD_SSBD) | F(VIRT_SSBD) |
> -		F(AMD_SSB_NO) | F(AMD_STIBP) | F(AMD_STIBP_ALWAYS_ON)
> +		F(AMD_SSB_NO) | F(AMD_STIBP) | F(AMD_STIBP_ALWAYS_ON) | F(AMD_PSFD)

Please note that this patch has a pre-req against the PSFD support that
defines this feature:

https://lore.kernel.org/lkml/20210406155004.230790-2-rsaripal@xxxxxxx/#t

Thanks,
Tom

>  	);
>  
>  	/*
>