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

David Edmondson
2021-02-24T14:42:20Z

On Tuesday, 2021-02-23 at 15:13:54 -08, 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.

v3 now always shows the PDPTRs if they exist.

dme.
--
I've got a little black book with my poems in.