vhost-user: don't merge regions with different fds

vhost currently merges regions with contiguious virtual and physical
addresses.  This breaks for vhost-user since that also needs fds to
match.

Add a vhost_ops entry to compare the fds for vhost-user only.

Cc: qemu-stable@nongnu.org
Cc: Victor Kaplansky <victork@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 72d0c9e9ae..392d848819 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -260,6 +260,13 @@ static void vhost_dev_assign_memory(struct vhost_dev *dev,
             continue;
         }
 
+        if (dev->vhost_ops->vhost_backend_can_merge &&
+            !dev->vhost_ops->vhost_backend_can_merge(dev, uaddr, size,
+                                                     reg->userspace_addr,
+                                                     reg->memory_size)) {
+            continue;
+        }
+
         if (merged) {
             --to;
             assert(to >= 0);