3 files changed, 7 insertions, 7 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a3b25a524c9..220c83b0fbd 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3466,10 +3466,9 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm,
 int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
                                       struct kvm_dirty_log *log)
 {
-        int r, i;
+        int r;
         struct kvm_memory_slot *memslot;
         unsigned long n;
-        unsigned long is_dirty = 0;
 
         mutex_lock(&kvm->slots_lock);
 
@@ -3484,11 +3483,8 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 
         n = kvm_dirty_bitmap_bytes(memslot);
 
-        for (i = 0; !is_dirty && i < n/sizeof(long); i++)
-                is_dirty = memslot->dirty_bitmap[i];
-
         /* If nothing is dirty, don't bother messing with page tables. */
-        if (is_dirty) {
+        if (memslot->nr_dirty_pages) {
                 struct kvm_memslots *slots, *old_slots;
                 unsigned long *dirty_bitmap;
 
@@ -3503,6 +3499,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
                         goto out;
                 memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots));
                 slots->memslots[log->slot].dirty_bitmap = dirty_bitmap;
+                slots->memslots[log->slot].nr_dirty_pages = 0;
                 slots->generation++;
 
                 old_slots = kvm->memslots;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c6a2ec92584..7c654aa46b6 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -181,6 +181,7 @@ struct kvm_memory_slot {
         unsigned long *rmap;
         unsigned long *dirty_bitmap;
         unsigned long *dirty_bitmap_head;
+        unsigned long nr_dirty_pages;
         struct kvm_lpage_info *lpage_info[KVM_NR_PAGE_SIZES - 1];
         unsigned long userspace_addr;
         int user_alloc;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 4c5b9a23967..af5c988cafc 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -625,6 +625,7 @@ static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot)
                 return -ENOMEM;
 
         memslot->dirty_bitmap_head = memslot->dirty_bitmap;
+        memslot->nr_dirty_pages = 0;
         return 0;
 }
 #endif /* !CONFIG_S390 */
@@ -1491,7 +1492,8 @@ void mark_page_dirty_in_slot(struct kvm *kvm, struct kvm_memory_slot *memslot,
         if (memslot && memslot->dirty_bitmap) {
                 unsigned long rel_gfn = gfn - memslot->base_gfn;
 
-                __set_bit_le(rel_gfn, memslot->dirty_bitmap);
+                if (!__test_and_set_bit_le(rel_gfn, memslot->dirty_bitmap))
+                        memslot->nr_dirty_pages++;
         }
 }