Re: [PATCH 2/6] x86: KVM: Enable AMX-FP16 CPUID and expose it to guest

[Paolo Bonzini]

On 11/2/22 19:14, Dave Hansen wrote:
> >   
> >   	kvm_cpu_cap_mask(CPUID_7_1_EAX,
> > -		F(AVX_VNNI) | F(AVX512_BF16) | F(CMPCCXADD)
> > +		F(AVX_VNNI) | F(AVX512_BF16) | F(CMPCCXADD) | F(AMX_FP16)
> >   	);
> >   
> >   	kvm_cpu_cap_mask(CPUID_D_1_EAX,
>
> KVM folks, is the idea that every feature that is enumerated to a guest
> needs to be in one of these masks?  Or is there something special about
> the features in these masks?

Yes, all features are vetted manually to see whether they require new 
MSRs and the like.  Therefore, anything that userspace can set in the 
guest's CPUID must be in the list.

Paolo