KVM: MMU: unalias gfn before sp->gfns[] comparison in sync_page

sp->gfns[] contain unaliased gfns, but gpte might contain pointer
to aliased region.

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 15e379eaf3b0..22f13797f521 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -586,7 +586,7 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
                 unsigned pte_access;
                 pt_element_t gpte;
                 gpa_t pte_gpa;
-                gfn_t gfn = sp->gfns[i];
+                gfn_t gfn;
 
                 if (!is_shadow_present_pte(sp->spt[i]))
                         continue;
@@ -597,8 +597,9 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
                                           sizeof(pt_element_t)))
                         return -EINVAL;
 
-                if (gpte_to_gfn(gpte) != gfn || !is_present_gpte(gpte) ||
-                    !(gpte & PT_ACCESSED_MASK)) {
+                gfn = gpte_to_gfn(gpte);
+                if (unalias_gfn(vcpu->kvm, gfn) != sp->gfns[i] ||
+                      !is_present_gpte(gpte) || !(gpte & PT_ACCESSED_MASK)) {
                         u64 nonpresent;
 
                         rmap_remove(vcpu->kvm, &sp->spt[i]);