vhost+postcopy: Wire up POSTCOPY_END notify

Wire up a call to VHOST_USER_POSTCOPY_END message to the vhost clients
right before we ask the listener thread to shutdown.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/virtio/trace-events

@@ -7,6 +7,8 @@ vhost_region_add_section_abut(const char *name, uint64_t new_size) "%s: 0x%"PRIx
 vhost_section(const char *name, int r) "%s:%d"
 
 # hw/virtio/vhost-user.c
+vhost_user_postcopy_end_entry(void) ""
+vhost_user_postcopy_end_exit(void) ""
 vhost_user_postcopy_fault_handler(const char *name, uint64_t fault_address, int nregions) "%s: @0x%"PRIx64" nregions:%d"
 vhost_user_postcopy_fault_handler_loop(int i, uint64_t client_base, uint64_t size) "%d: client 0x%"PRIx64" +0x%"PRIx64
 vhost_user_postcopy_fault_handler_found(int i, uint64_t region_offset, uint64_t rb_offset) "%d: region_offset: 0x%"PRIx64" rb_offset:0x%"PRIx64

hw/virtio/vhost-user.c

@@ -1114,6 +1114,37 @@ static int vhost_user_postcopy_listen(struct vhost_dev *dev, Error **errp)
     return 0;
 }
 
+/*
+ * Called at the end of postcopy
+ */
+static int vhost_user_postcopy_end(struct vhost_dev *dev, Error **errp)
+{
+    VhostUserMsg msg = {
+        .hdr.request = VHOST_USER_POSTCOPY_END,
+        .hdr.flags = VHOST_USER_VERSION | VHOST_USER_NEED_REPLY_MASK,
+    };
+    int ret;
+    struct vhost_user *u = dev->opaque;
+
+    trace_vhost_user_postcopy_end_entry();
+    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
+        error_setg(errp, "Failed to send postcopy_end to vhost");
+        return -1;
+    }
+
+    ret = process_message_reply(dev, &msg);
+    if (ret) {
+        error_setg(errp, "Failed to receive reply to postcopy_end");
+        return ret;
+    }
+    postcopy_unregister_shared_ufd(&u->postcopy_fd);
+    u->postcopy_fd.handler = NULL;
+
+    trace_vhost_user_postcopy_end_exit();
+
+    return 0;
+}
+
 static int vhost_user_postcopy_notifier(NotifierWithReturn *notifier,
                                         void *opaque)
 {
@@ -1139,6 +1170,9 @@ static int vhost_user_postcopy_notifier(NotifierWithReturn *notifier,
     case POSTCOPY_NOTIFY_INBOUND_LISTEN:
         return vhost_user_postcopy_listen(dev, pnd->errp);
 
+    case POSTCOPY_NOTIFY_INBOUND_END:
+        return vhost_user_postcopy_end(dev, pnd->errp);
+
     default:
         /* We ignore notifications we don't know */
         break;

migration/postcopy-ram.c

@@ -413,6 +413,13 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis)
     trace_postcopy_ram_incoming_cleanup_entry();
 
     if (mis->have_fault_thread) {
+        Error *local_err = NULL;
+
+        if (postcopy_notify(POSTCOPY_NOTIFY_INBOUND_END, &local_err)) {
+            error_report_err(local_err);
+            return -1;
+        }
+
         if (qemu_ram_foreach_block(cleanup_range, mis)) {
             return -1;
         }

migration/postcopy-ram.h

@@ -132,6 +132,7 @@ enum PostcopyNotifyReason {
     POSTCOPY_NOTIFY_PROBE = 0,
     POSTCOPY_NOTIFY_INBOUND_ADVISE,
     POSTCOPY_NOTIFY_INBOUND_LISTEN,
+    POSTCOPY_NOTIFY_INBOUND_END,
 };
 
 struct PostcopyNotifyData {