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KVM: MMU: mode specific sync_page

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Examine guest pagetable and bring the shadow back in sync. Caller is responsible
for local TLB flush before re-entering guest mode.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Marcelo Tosatti
2008-09-23 13:18:33 -03:00
committed by Avi Kivity
parent 38187c830c
commit e8bc217aef
3 changed files with 66 additions and 0 deletions
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54
arch/x86/kvm/paging_tmpl.h
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@@ -507,6 +507,60 @@ static void FNAME(prefetch_page)(struct kvm_vcpu *vcpu,
}
}
/*
* Using the cached information from sp->gfns is safe because:
* - The spte has a reference to the struct page, so the pfn for a given gfn
* can't change unless all sptes pointing to it are nuked first.
* - Alias changes zap the entire shadow cache.
*/
static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
{
int i, offset, nr_present;
offset = nr_present = 0;
if (PTTYPE == 32)
offset = sp->role.quadrant << PT64_LEVEL_BITS;
for (i = 0; i < PT64_ENT_PER_PAGE; i++) {
unsigned pte_access;
pt_element_t gpte;
gpa_t pte_gpa;
gfn_t gfn = sp->gfns[i];
if (!is_shadow_present_pte(sp->spt[i]))
continue;
pte_gpa = gfn_to_gpa(sp->gfn);
pte_gpa += (i+offset) * sizeof(pt_element_t);
if (kvm_read_guest_atomic(vcpu->kvm, pte_gpa, &gpte,
sizeof(pt_element_t)))
return -EINVAL;
if (gpte_to_gfn(gpte) != gfn || !is_present_pte(gpte) ||
!(gpte & PT_ACCESSED_MASK)) {
u64 nonpresent;
rmap_remove(vcpu->kvm, &sp->spt[i]);
if (is_present_pte(gpte))
nonpresent = shadow_trap_nonpresent_pte;
else
nonpresent = shadow_notrap_nonpresent_pte;
set_shadow_pte(&sp->spt[i], nonpresent);
continue;
}
nr_present++;
pte_access = sp->role.access & FNAME(gpte_access)(vcpu, gpte);
set_spte(vcpu, &sp->spt[i], pte_access, 0, 0,
is_dirty_pte(gpte), 0, gfn,
spte_to_pfn(sp->spt[i]), true);
}
return !nr_present;
}
#undef pt_element_t
#undef guest_walker
#undef shadow_walker