Re: [RFC 05/12] KVM/VMX: Use the new host mapping API for mapping nested vmptr

[KarimAllah Ahmed]

On 02/05/2018 11:15 PM, Jim Mattson wrote:
> On Mon, Feb 5, 2018 at 10:49 AM KarimAllah Ahmed <karahmed@xxxxxxxxx> wrote:
>
>
> > @@ -7410,19 +7410,17 @@ static int handle_vmon(struct kvm_vcpu *vcpu)
> >                   return kvm_skip_emulated_instruction(vcpu);
> >           }
>
> > -       page = kvm_vcpu_gpa_to_page(vcpu, vmptr);
> > -       if (is_error_page(page)) {
> > +       if (!kvm_vcpu_gpa_to_host_mapping(vcpu, vmptr, &mapping, true)) {
> >                   nested_vmx_failInvalid(vcpu);
> >                   return kvm_skip_emulated_instruction(vcpu);
> >           }
> > -       if (*(u32 *)kmap(page) != VMCS12_REVISION) {
> > -               kunmap(page);
> > -               kvm_release_page_clean(page);
> > +       if (*(u32 *)mapping.kaddr != VMCS12_REVISION) {
> > +               kvm_release_host_mapping(&mapping, false);
> >                   nested_vmx_failInvalid(vcpu);
> >                   return kvm_skip_emulated_instruction(vcpu);
> >           }
> > -       kunmap(page);
> > -       kvm_release_page_clean(page);
> > +
> > +       kvm_release_host_mapping(&mapping, false);
>
> Why go through this explicit mapping/release dance? Why not just:
>
> uint32_t revision;
> ...
> if (kvm_read_guest(vcpu->kvm, vmptr, &revision, sizeof(revision)) ||
>       revision != VMCS12_REVISION) {
>           nested_vmx_failInvalid(vcpu);
>           return kvm_skip_emulated_instruction(vcpu);
> }

Fair enough, I will update.
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