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SubjectRe: [PATCH v4 3/6] x86: KVM: Advertise AVX-IFMA CPUID to user space
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On 11/19/2022 12:08 AM, Sean Christopherson wrote:
> 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@linux.intel.com>
>> ---
>> 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.

That's very careful. Thank you~
--
Regards,
Jiaxi

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