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 <[e-mail]>
Signed-off-by: Avi Kivity <[e-mail]>

drivers/kvm/kvm_main.c

···
 	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;