1 files changed, 63 insertions, 8 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3a7fcff81af6..442ee7d90946 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3780,6 +3780,12 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
 
 	mutex_lock(&kvm->slots_lock);
 
+	/*
+	 * Flush potentially hardware-cached dirty pages to dirty_bitmap.
+	 */
+	if (kvm_x86_ops->flush_log_dirty)
+		kvm_x86_ops->flush_log_dirty(kvm);
+
 	r = kvm_get_dirty_log_protect(kvm, log, &is_dirty);
 
 	/*
@@ -7533,6 +7539,56 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 	return 0;
 }
 
+static void kvm_mmu_slot_apply_flags(struct kvm *kvm,
+				     struct kvm_memory_slot *new)
+{
+	/* Still write protect RO slot */
+	if (new->flags & KVM_MEM_READONLY) {
+		kvm_mmu_slot_remove_write_access(kvm, new);
+		return;
+	}
+
+	/*
+	 * Call kvm_x86_ops dirty logging hooks when they are valid.
+	 *
+	 * kvm_x86_ops->slot_disable_log_dirty is called when:
+	 *
+	 *  - KVM_MR_CREATE with dirty logging is disabled
+	 *  - KVM_MR_FLAGS_ONLY with dirty logging is disabled in new flag
+	 *
+	 * The reason is, in case of PML, we need to set D-bit for any slots
+	 * with dirty logging disabled in order to eliminate unnecessary GPA
+	 * logging in PML buffer (and potential PML buffer full VMEXT). This
+	 * guarantees leaving PML enabled during guest's lifetime won't have
+	 * any additonal overhead from PML when guest is running with dirty
+	 * logging disabled for memory slots.
+	 *
+	 * kvm_x86_ops->slot_enable_log_dirty is called when switching new slot
+	 * to dirty logging mode.
+	 *
+	 * If kvm_x86_ops dirty logging hooks are invalid, use write protect.
+	 *
+	 * In case of write protect:
+	 *
+	 * Write protect all pages for dirty logging.
+	 *
+	 * All the sptes including the large sptes which point to this
+	 * slot are set to readonly. We can not create any new large
+	 * spte on this slot until the end of the logging.
+	 *
+	 * See the comments in fast_page_fault().
+	 */
+	if (new->flags & KVM_MEM_LOG_DIRTY_PAGES) {
+		if (kvm_x86_ops->slot_enable_log_dirty)
+			kvm_x86_ops->slot_enable_log_dirty(kvm, new);
+		else
+			kvm_mmu_slot_remove_write_access(kvm, new);
+	} else {
+		if (kvm_x86_ops->slot_disable_log_dirty)
+			kvm_x86_ops->slot_disable_log_dirty(kvm, new);
+	}
+}
+
 void kvm_arch_commit_memory_region(struct kvm *kvm,
 				struct kvm_userspace_memory_region *mem,
 				const struct kvm_memory_slot *old,
@@ -7562,16 +7618,15 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
 	new = id_to_memslot(kvm->memslots, mem->slot);
 
 	/*
-	 * Write protect all pages for dirty logging.
+	 * Set up write protection and/or dirty logging for the new slot.
 	 *
-	 * All the sptes including the large sptes which point to this
-	 * slot are set to readonly. We can not create any new large
-	 * spte on this slot until the end of the logging.
-	 *
-	 * See the comments in fast_page_fault().
+	 * For KVM_MR_DELETE and KVM_MR_MOVE, the shadow pages of old slot have
+	 * been zapped so no dirty logging staff is needed for old slot. For
+	 * KVM_MR_FLAGS_ONLY, the old slot is essentially the same one as the
+	 * new and it's also covered when dealing with the new slot.
 	 */
-	if ((change != KVM_MR_DELETE) && (new->flags & KVM_MEM_LOG_DIRTY_PAGES))
-		kvm_mmu_slot_remove_write_access(kvm, new);
+	if (change != KVM_MR_DELETE)
+		kvm_mmu_slot_apply_flags(kvm, new);
 }
 
 void kvm_arch_flush_shadow_all(struct kvm *kvm)