KVM: MMU: Implement guest page fault bypass for nonpae
I spent an hour worrying why I see so many guest page faults on FC6 i386.
Turns out bypass wasn't implemented for nonpae. Implement it so it doesn't
happen again.
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h
index bf15d12..92b9313 100644
--- a/drivers/kvm/paging_tmpl.h
+++ b/drivers/kvm/paging_tmpl.h
@@ -486,19 +486,22 @@
static void FNAME(prefetch_page)(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp)
{
- int i;
+ int i, offset = 0;
pt_element_t *gpt;
struct page *page;
- if (sp->role.metaphysical || PTTYPE == 32) {
+ if (sp->role.metaphysical
+ || (PTTYPE == 32 && sp->role.level > PT_PAGE_TABLE_LEVEL)) {
nonpaging_prefetch_page(vcpu, sp);
return;
}
+ if (PTTYPE == 32)
+ offset = sp->role.quadrant << PT64_LEVEL_BITS;
page = gfn_to_page(vcpu->kvm, sp->gfn);
gpt = kmap_atomic(page, KM_USER0);
for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
- if (is_present_pte(gpt[i]))
+ if (is_present_pte(gpt[offset + i]))
sp->spt[i] = shadow_trap_nonpresent_pte;
else
sp->spt[i] = shadow_notrap_nonpresent_pte;