From: Peter Xu <peterx@redhat.com>
Date: Wed, 8 May 2019 09:15:46 +0000 (+0800)
Subject: KVM: Fix kvm_clear_dirty_log_protect off-by-(minus-)one
X-Git-Tag: v5.4-rc1~940^2~12
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=53eac7a8f8cf3d7dc5ecac1946f31442f5eee5f3;p=platform%2Fkernel%2Flinux-rpi.git

KVM: Fix kvm_clear_dirty_log_protect off-by-(minus-)one

Just imaging the case where num_pages < BITS_PER_LONG, then the loop
will be skipped while it shouldn't.

Signed-off-by: Peter Xu <peterx@redhat.com>
Fixes: 2a31b9db153530df4aa02dac8c32837bf5f47019
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index ad39c57..7883e0a 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1264,8 +1264,8 @@ int kvm_clear_dirty_log_protect(struct kvm *kvm,
 		return -EFAULT;
 
 	spin_lock(&kvm->mmu_lock);
-	for (offset = log->first_page,
-	     i = offset / BITS_PER_LONG, n = log->num_pages / BITS_PER_LONG; n--;
+	for (offset = log->first_page, i = offset / BITS_PER_LONG,
+		 n = DIV_ROUND_UP(log->num_pages, BITS_PER_LONG); n--;
 	     i++, offset += BITS_PER_LONG) {
 		unsigned long mask = *dirty_bitmap_buffer++;
 		atomic_long_t *p = (atomic_long_t *) &dirty_bitmap[i];