[Qemu-devel] [PATCH v2] vhost-user: fix reconnection support for host notifier

[Tiwei Bie <tiwei.bie@intel.com>]

We need to destroy the host notifiers when cleaning up
the backend. Otherwise, some resources are not released
after the connection is closed, and it may prevent the
external backend from reopening them (e.g. VFIO files)
during restart.

Fixes: 44866521bd6e ("vhost-user: support registering external host notifiers")
Cc: qemu-stable@nongnu.org

Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
---
v2:
- Drop superfluous memset() (Marc-André);
- Factor the notifier code in a separate function (Marc-André);

 hw/virtio/vhost-user.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 4ca5b2551e..e27a2a4647 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -226,6 +226,20 @@ static bool ioeventfd_enabled(void)
     return !kvm_enabled() || kvm_eventfds_enabled();
 }
 
+static void
+vhost_user_host_notifiers_cleanup(VhostUserState *user)
+{
+    int i;
+
+    for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
+        if (user->notifier[i].addr) {
+            object_unparent(OBJECT(&user->notifier[i].mr));
+            munmap(user->notifier[i].addr, qemu_real_host_page_size);
+            user->notifier[i].addr = NULL;
+        }
+    }
+}
+
 static int vhost_user_read_header(struct vhost_dev *dev, VhostUserMsg *msg)
 {
     struct vhost_user *u = dev->opaque;
@@ -1469,6 +1483,9 @@ static int vhost_user_backend_cleanup(struct vhost_dev *dev)
     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
 
     u = dev->opaque;
+    if (dev->vq_index == 0) {
+        vhost_user_host_notifiers_cleanup(u->user);
+    }
     if (u->postcopy_notifier.notify) {
         postcopy_remove_notifier(&u->postcopy_notifier);
         u->postcopy_notifier.notify = NULL;
@@ -1898,19 +1915,10 @@ bool vhost_user_init(VhostUserState *user, CharBackend *chr, Error **errp)
 
 void vhost_user_cleanup(VhostUserState *user)
 {
-    int i;
-
     if (!user->chr) {
         return;
     }
-
-    for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
-        if (user->notifier[i].addr) {
-            object_unparent(OBJECT(&user->notifier[i].mr));
-            munmap(user->notifier[i].addr, qemu_real_host_page_size);
-            user->notifier[i].addr = NULL;
-        }
-    }
+    vhost_user_host_notifiers_cleanup(user);
     user->chr = NULL;
 }
 
-- 
2.17.1