Re: [PATCH v4 3/6] x86: KVM: Advertise AVX-IFMA CPUID to user space

[Sean Christopherson]

On Fri, Nov 18, 2022, Jiaxi Chen wrote:
> AVX-IFMA is a new instruction in the latest Intel platform Sierra
> Forest. This instruction packed multiplies unsigned 52-bit integers and
> adds the low/high 52-bit products to Qword Accumulators.
> 
> The bit definition:
> CPUID.(EAX=7,ECX=1):EAX[bit 23]
> 
> This CPUID is exposed to user space. Besides, there is no other VMX
> control for this instruction.
> 
> Signed-off-by: Jiaxi Chen <jiaxi.chen@xxxxxxxxxxxxxxx>
> ---
>  arch/x86/include/asm/cpufeatures.h | 1 +
>  arch/x86/kvm/cpuid.c               | 4 ++--
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> index df4a7f7505a9..159f8b9898bf 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -310,6 +310,7 @@
>  #define X86_FEATURE_AVX512_BF16		(12*32+ 5) /* AVX512 BFLOAT16 instructions */
>  #define X86_FEATURE_CMPCCXADD           (12*32+ 7) /* CMPccXADD instructions */
>  #define X86_FEATURE_AMX_FP16		(12*32+21) /* AMX fp16 Support */
> +#define X86_FEATURE_AVX_IFMA            (12*32+23) /* Support for VPMADD52[H,L]UQ */
>  
>  /* AMD-defined CPU features, CPUID level 0x80000008 (EBX), word 13 */
>  #define X86_FEATURE_CLZERO		(13*32+ 0) /* CLZERO instruction */
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 2a334d4cd04e..5726afb2d14c 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -657,8 +657,8 @@ void kvm_set_cpu_caps(void)
>  		kvm_cpu_cap_set(X86_FEATURE_SPEC_CTRL_SSBD);
>  
>  	kvm_cpu_cap_mask(CPUID_7_1_EAX,
> -		F(AVX_VNNI) | F(AVX512_BF16) | F(CMPCCXADD) | F(AMX_FP16)
> -	);
> +		F(AVX_VNNI) | F(AVX512_BF16) | F(CMPCCXADD) | F(AMX_FP16) |
> +		F(AVX_IFMA));

Please keep the terminating paranthesis+semicolon on a separate line.  KVM isn't
100% consistent (as usual), but I would rather "fix" the cases that don't put
the terminators on their own line.