[RFC PATCH 08/27] vhost: Add a flag for software assisted Live Migration

[Eugenio Pérez]

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 include/hw/virtio/vhost.h |  1 +
 hw/virtio/vhost.c         | 17 +++++++++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index 93cc3f1ae3..ef920a8076 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -84,6 +84,7 @@ struct vhost_dev {
     uint64_t backend_cap;
     bool started;
     bool log_enabled;
+    bool sw_lm_enabled;
     uint64_t log_size;
     VhostShadowVirtqueue *sw_lm_shadow_vq[2];
     VirtIOHandleOutput sw_lm_vq_handler;
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index a55b684b5f..1d55e26d45 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -988,11 +988,16 @@ static int vhost_sw_live_migration_start(struct vhost_dev 
*dev)
 static int vhost_sw_live_migration_enable(struct vhost_dev *dev,
                                           bool enable_lm)
 {
+    int r;
+
     if (enable_lm) {
-        return vhost_sw_live_migration_start(dev);
+        r = vhost_sw_live_migration_start(dev);
     } else {
-        return vhost_sw_live_migration_stop(dev);
+        r = vhost_sw_live_migration_stop(dev);
     }
+
+    dev->sw_lm_enabled = enable_lm;
+    return r;
 }
 
 static void vhost_sw_lm_global_start(MemoryListener *listener)
@@ -1466,6 +1471,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     hdev->log = NULL;
     hdev->log_size = 0;
     hdev->log_enabled = false;
+    hdev->sw_lm_enabled = false;
     hdev->started = false;
     memory_listener_register(&hdev->memory_listener, &address_space_memory);
     QLIST_INSERT_HEAD(&vhost_devices, hdev, entry);
@@ -1571,6 +1577,13 @@ void vhost_dev_disable_notifiers(struct vhost_dev *hdev, 
VirtIODevice *vdev)
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
     int i, r;
 
+    if (hdev->sw_lm_enabled) {
+        /* We've been called after migration is completed, so no need to
+           disable it again
+        */
+        return;
+    }
+
     for (i = 0; i < hdev->nvqs; ++i) {
         r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
                                          false);
-- 
2.18.4