KVM: MMU: large page update_pte issue with non-PAE 32-bit guests (res…

…end) kvm_mmu_pte_write() does not handle 32-bit non-PAE large page backed guests properly. It will instantiate two 2MB sptes pointing to the same physical 2MB page when a guest large pte update is trapped. Instead of duplicating code to handle this, disallow directory level updates to happen through kvm_mmu_pte_write(), so the two 2MB sptes emulating one guest 4MB pte can be correctly created by the page fault handling path. Signed-off-by: Marcelo Tosatti <[email protected]> Signed-off-by: Avi Kivity <[email protected]>
chewitt · Jun 24, 2008 · 3094538 · 3094538
1 parent 6597ca0
commit 3094538
Showing 1 changed file with 7 additions and 5 deletions.
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
@@ -1581,11 +1581,13 @@ static void mmu_pte_write_new_pte(struct kvm_vcpu *vcpu,
 				  u64 *spte,
 				  const void *new)
 {
-	if ((sp->role.level != PT_PAGE_TABLE_LEVEL)
-	    && !vcpu->arch.update_pte.largepage) {
-		++vcpu->kvm->stat.mmu_pde_zapped;
-		return;
-	}
+	if (sp->role.level != PT_PAGE_TABLE_LEVEL) {
+		if (!vcpu->arch.update_pte.largepage ||
+		    sp->role.glevels == PT32_ROOT_LEVEL) {
+			++vcpu->kvm->stat.mmu_pde_zapped;
+			return;
+		}
+        }
 
 	++vcpu->kvm->stat.mmu_pte_updated;
 	if (sp->role.glevels == PT32_ROOT_LEVEL)