KVM: Fix dirty page log bitmap size/access calculation

Since dirty_bitmap is an unsigned long array, the alignment and size need
to take that into account.

Signed-off-by: Uri Lublin <uril@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index edff405..e710810 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -792,9 +792,9 @@
 	if (!memslot->dirty_bitmap)
 		goto out;
 
-	n = ALIGN(memslot->npages, 8) / 8;
+	n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
 
-	for (i = 0; !any && i < n; ++i)
+	for (i = 0; !any && i < n/sizeof(long); ++i)
 		any = memslot->dirty_bitmap[i];
 
 	r = -EFAULT;