vhost: Fix memory region section comparison

Using memcmp to compare structures wasn't safe,
as I found out on ARM when I was getting falce miscompares.

Use the helper function for comparing the MRSs.

Fixes: ade6d081fc33948e56e6 ("vhost: Regenerate region list from changed sections list")
Cc: qemu-stable@nongnu.org
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20190814175535.2023-4-dgilbert@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit 3fc4a64cbaed2ddee4c60ddc06740b320e18ab82)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index bc899fc60e8bad1651340910c1ca50cb0e16f924..2ef4bc720f04ddadca3305a73df2ae1830eb76fd 100644 (file)
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -451,8 +451,13 @@ static void vhost_commit(MemoryListener *listener)
         changed = true;
     } else {
         /* Same size, lets check the contents */
-        changed = n_old_sections && memcmp(dev->mem_sections, old_sections,
-                         n_old_sections * sizeof(old_sections[0])) != 0;
+        for (int i = 0; i < n_old_sections; i++) {
+            if (!MemoryRegionSection_eq(&old_sections[i],
+                                        &dev->mem_sections[i])) {
+                changed = true;
+                break;
+            }
+        }
     }
 
     trace_vhost_commit(dev->started, changed);