Re: [PATCH 2/4] KVM: SVM: use NPT page attributes

[Xiao Guangrong]

On 07/09/2015 11:18 PM, Paolo Bonzini wrote:
> On 09/07/2015 04:30, Xiao Guangrong wrote:
> > > > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> > > > > index 602b974a60a6..0f125c1860ec 100644
> > > > > --- a/arch/x86/kvm/svm.c
> > > > > +++ b/arch/x86/kvm/svm.c
> > > > > @@ -1085,6 +1085,47 @@ static u64 svm_compute_tsc_offset(struct
> > > > > kvm_vcpu *vcpu, u64 target_tsc)
> > > > >         return target_tsc - tsc;
> > > > >     }
> > > > >
> > > > > +static void svm_set_guest_pat(struct vcpu_svm *svm, u64 *g_pat)
> > > > > +{
> > > > > +    struct kvm_vcpu *vcpu = &svm->vcpu;
> > > > > +
> > > > > +    /* Unlike Intel, AMD takes the guest's CR0.CD into account.
> > > >
> > > > I noticed this code in svm_set_cr0():
> > > >
> > > >       if (!(vcpu->kvm->arch.disabled_quirks & KVM_QUIRK_CD_NW_CLEARED))
> > > >           cr0 &= ~(X86_CR0_CD | X86_CR0_NW);
> > > >
> > > > gCR0.CD is hidden to CPU if KVM_QUIRK_CD_NW_CLEARED is not set and looks
> > > > like it is the normal case after grepping Qemu code.
>
> Hi Xiao,
>
> yes, this is correct.  QEMU still does not have support for disabling
> "quirks", so gCR0.CD is currently hidden on SVM.  I would like to
> include this series in 4.2, while for 4.3 I will disable the quirk above
> altogether (it is superseded by the way PAT is forced to all-WB).

That plan sounds good to me.

You will drop disabled_quirks completely or just enable it in Qemu? :)
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