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SubjectRe: [PATCH v5 8/9] KVM: MMU: combine guest pte read between fetch and pte prefetch
On Wed, Jul 07, 2010 at 09:23:15AM +0800, Xiao Guangrong wrote:
>
>
> Marcelo Tosatti wrote:
>
> >> -
> >> - first_pte_gpa = gfn_to_gpa(sp->gfn) +
> >> - (offset + i) * sizeof(pt_element_t);
> >> -
> >> - if (kvm_read_guest_atomic(vcpu->kvm, first_pte_gpa, gptep,
> >> - sizeof(gptep)) < 0)
> >> - return;
> >> + gptep = gw->prefetch_ptes;
> >
> > Where do you reread the gpte in the prefetch path?
> >
>
> Marcelo,
>
> Thanks for your review.
>
> Below codes read gptes in the prefetch path:
>
> index = sptep - sp->spt;
> i = index & ~(PTE_PREFETCH_NUM - 1);
> max = index | (PTE_PREFETCH_NUM - 1);
>
> if (PTTYPE == 32)
> offset = sp->role.quadrant << PT64_LEVEL_BITS;
>
> first_pte_gpa = gfn_to_gpa(sp->gfn) +
> (offset + i) * sizeof(pt_element_t);
>
> if (kvm_read_guest_atomic(vcpu->kvm, first_pte_gpa, gptep,
> sizeof(gptep)) < 0)
> return;
>
> It reads the 16 aligned items around sptep's corresponding gpte and this gpte
> is also in this area. :-)

But you removed that in patch 8?


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