Re: [PATCH v2 1/3] KVM: x86: dump_vmcs should not assume GUEST_IA32_EFER is valid

Sean Christopherson
2021-02-24T00:31:37Z

On Tue, Feb 23, 2021, Jim Mattson wrote:
> On Tue, Feb 23, 2021 at 2:51 PM Sean Christopherson <seanjc@google.com> wrote:
> >
> > On Fri, Feb 19, 2021, David Edmondson wrote:
> > > If the VM entry/exit controls for loading/saving MSR_EFER are either
> > > not available (an older processor or explicitly disabled) or not
> > > used (host and guest values are the same), reading GUEST_IA32_EFER
> > > from the VMCS returns an inaccurate value.
> > >
> > > Because of this, in dump_vmcs() don't use GUEST_IA32_EFER to decide
> > > whether to print the PDPTRs - do so if the EPT is in use and CR4.PAE
> > > is set.
> >
> > This isn't necessarily correct either. In a way, it's less correct as PDPTRs
> > are more likely to be printed when they shouldn't, assuming most guests are
> > 64-bit guests. It's annoying to calculate the effective guest EFER, but so
> > awful that it's worth risking confusion over PDTPRs.
>
> I still prefer a dump_vmcs that always dumps every VMCS field.

I'm a-ok with that approach.