---

yaml
---
r: 315901
b: refs/heads/master
c: 49fde34
h: refs/heads/master
i:
  315899: 24d31b0
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 6e7d035407dc402a313e466c4f7ccb21aaed0da2
+refs/heads/master: 49fde3406f3266c5af9430467672c20b63a31e83

trunk/arch/x86/kvm/mmu.c

@@ -145,7 +145,8 @@ module_param(dbg, bool, 0644);
 #define CREATE_TRACE_POINTS
 #include "mmutrace.h"
 
-#define SPTE_HOST_WRITEABLE (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
+#define SPTE_HOST_WRITEABLE	(1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
+#define SPTE_MMU_WRITEABLE	(1ULL << (PT_FIRST_AVAIL_BITS_SHIFT + 1))
 
 #define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level)
 
@@ -1084,42 +1085,59 @@ static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep)
 		kvm_flush_remote_tlbs(vcpu->kvm);
 }
 
+static bool spte_is_locklessly_modifiable(u64 spte)
+{
+	return !(~spte & (SPTE_HOST_WRITEABLE | SPTE_MMU_WRITEABLE));
+}
+
 /*
- * Write-protect on the specified @sptep due to dirty page logging or
- * protecting shadow page table. @flush indicates whether tlb need be
- * flushed.
+ * Write-protect on the specified @sptep, @pt_protect indicates whether
+ * spte writ-protection is caused by protecting shadow page table.
+ * @flush indicates whether tlb need be flushed.
+ *
+ * Note: write protection is difference between drity logging and spte
+ * protection:
+ * - for dirty logging, the spte can be set to writable at anytime if
+ *   its dirty bitmap is properly set.
+ * - for spte protection, the spte can be writable only after unsync-ing
+ *   shadow page.
  *
  * Return true if the spte is dropped.
  */
-static bool spte_write_protect(struct kvm *kvm, u64 *sptep, bool *flush)
+static bool
+spte_write_protect(struct kvm *kvm, u64 *sptep, bool *flush, bool pt_protect)
 {
 	u64 spte = *sptep;
 
-	if (!is_writable_pte(spte))
+	if (!is_writable_pte(spte) &&
+	      !(pt_protect && spte_is_locklessly_modifiable(spte)))
 		return false;
 
 	rmap_printk("rmap_write_protect: spte %p %llx\n", sptep, *sptep);
 
-	*flush |= true;
-
-	if (__drop_large_spte(kvm, sptep))
+	if (__drop_large_spte(kvm, sptep)) {
+		*flush |= true;
 		return true;
+	}
 
+	if (pt_protect)
+		spte &= ~SPTE_MMU_WRITEABLE;
 	spte = spte & ~PT_WRITABLE_MASK;
-	mmu_spte_update(sptep, spte);
+
+	*flush |= mmu_spte_update(sptep, spte);
 	return false;
 }
 
-static bool
-__rmap_write_protect(struct kvm *kvm, unsigned long *rmapp, int level)
+static bool __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp,
+				 int level, bool pt_protect)
 {
 	u64 *sptep;
 	struct rmap_iterator iter;
 	bool flush = false;
 
 	for (sptep = rmap_get_first(*rmapp, &iter); sptep;) {
 		BUG_ON(!(*sptep & PT_PRESENT_MASK));
-		if (spte_write_protect(kvm, sptep, &flush)) {
+		if (spte_write_protect(kvm, sptep, &flush, pt_protect)) {
 			sptep = rmap_get_first(*rmapp, &iter);
 			continue;
 		}
@@ -1148,7 +1166,7 @@ void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
 
 	while (mask) {
 		rmapp = &slot->rmap[gfn_offset + __ffs(mask)];
-		__rmap_write_protect(kvm, rmapp, PT_PAGE_TABLE_LEVEL);
+		__rmap_write_protect(kvm, rmapp, PT_PAGE_TABLE_LEVEL, false);
 
 		/* clear the first set bit */
 		mask &= mask - 1;
@@ -1167,7 +1185,7 @@ static bool rmap_write_protect(struct kvm *kvm, u64 gfn)
 	for (i = PT_PAGE_TABLE_LEVEL;
 	     i < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++i) {
 		rmapp = __gfn_to_rmap(gfn, i, slot);
-		write_protected |= __rmap_write_protect(kvm, rmapp, i);
+		write_protected |= __rmap_write_protect(kvm, rmapp, i, true);
 	}
 
 	return write_protected;
@@ -2296,8 +2314,10 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 		spte |= shadow_x_mask;
 	else
 		spte |= shadow_nx_mask;
+
 	if (pte_access & ACC_USER_MASK)
 		spte |= shadow_user_mask;
+
 	if (level > PT_PAGE_TABLE_LEVEL)
 		spte |= PT_PAGE_SIZE_MASK;
 	if (tdp_enabled)
@@ -2322,7 +2342,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 			goto done;
 		}
 
-		spte |= PT_WRITABLE_MASK;
+		spte |= PT_WRITABLE_MASK | SPTE_MMU_WRITEABLE;
 
 		if (!vcpu->arch.mmu.direct_map
 		    && !(pte_access & ACC_WRITE_MASK)) {
@@ -2351,8 +2371,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 				 __func__, gfn);
 			ret = 1;
 			pte_access &= ~ACC_WRITE_MASK;
-			if (is_writable_pte(spte))
-				spte &= ~PT_WRITABLE_MASK;
+			spte &= ~(PT_WRITABLE_MASK | SPTE_MMU_WRITEABLE);
 		}
 	}
 
@@ -3933,7 +3952,7 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
 			      !is_last_spte(pt[i], sp->role.level))
 				continue;
 
-			spte_write_protect(kvm, &pt[i], &flush);
+			spte_write_protect(kvm, &pt[i], &flush, false);
 		}
 	}
 	kvm_flush_remote_tlbs(kvm);