Re: [RFC 5/7] KVM: MMU: Add support for PKS emulation

[Paolo Bonzini]

On 27/01/21 04:00, Chenyi Qiang wrote:
> > >          if (pte_access & PT_USER_MASK)
> > >              pkr_bits = (vcpu->arch.pkru >> (pte_pkey * 2)) & 3;
> > > +        else if (!kvm_get_msr(vcpu, MSR_IA32_PKRS, &pkrs))
> > > +            pkr_bits = (pkrs >> (pte_pkey * 2)) & 3;
> >
> > You should be able to always use vcpu->arch.pkrs here.  So
> >
> > pkr = pte_access & PT_USER_MASK ? vcpu->arch.pkru : vcpu->arch.pkrs;
> > pkr_bits = (pkr >> pte_pkey * 2) & 3;
> Concerning vcpu->arch.pkrs would be the only use case in current 
> submitted patches, is it still necessary to shadow it?

Yes, please do.  kvm_get_msr is pretty slow, and the code becomes 
simpler too.

Paolo