Re: [PATCH] x86: kvm: Avoid guest page table walk when gpa_available is set

Brijesh Singh
2017-05-02T21:44:19Z

Hi Paolo,

>>
>> I've tried the below patch and it seems to work fine. This does not
>> consider
>> PIO case and as you rightly pointed PIO should trigger #NPF relatively
>> rarely.
>> At least so far in my runs I have not seen PIO causing #NPF. If this sounds
>> acceptable approach then I can submit v2 with these changes and remove
>> gpa_val
>> additional.
>
> PIO can certainly cause #NPF, albeit rarely, so this is not a viable one.
>

For SEV guest cases, we anyway want to avoid any guest page table walks
(even if it happens rarely). Sounds like we have to depend on gpa_val variable.
I will refresh the patch to address one of Ramdim's feedback
(move vcpu->arch.gpa_val assignment from handle_exit to pf_interception).

Brijesh