[v2,1/10] KVM: MMU: fix writable sync sp mapping

Commit Message

Xiao Guangrong June 25, 2010, 12:05 p.m. UTC

None

Patch

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 045a0f9..556a798 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1810,11 +1810,14 @@  static int mmu_need_write_protect(struct kvm_vcpu *vcpu, gfn_t gfn,
 	bool need_unsync = false;
 
 	for_each_gfn_indirect_valid_sp(vcpu->kvm, s, gfn, node) {
+		if (!can_unsync)
+			return 1;
+
 		if (s->role.level != PT_PAGE_TABLE_LEVEL)
 			return 1;
 
 		if (!need_unsync && !s->unsync) {
-			if (!can_unsync || !oos_shadow)
+			if (!oos_shadow)
 				return 1;
 			need_unsync = true;
 		}
@@ -1877,15 +1880,6 @@  static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 		if (!tdp_enabled && !(pte_access & ACC_WRITE_MASK))
 			spte &= ~PT_USER_MASK;
 
-		/*
-		 * Optimization: for pte sync, if spte was writable the hash
-		 * lookup is unnecessary (and expensive). Write protection
-		 * is responsibility of mmu_get_page / kvm_sync_page.
-		 * Same reasoning can be applied to dirty page accounting.
-		 */
-		if (!can_unsync && is_writable_pte(*sptep))
-			goto set_pte;
-
 		if (mmu_need_write_protect(vcpu, gfn, can_unsync)) {
 			pgprintk("%s: found shadow page for %lx, marking ro\n",
 				 __func__, gfn);