From 714d313805542063ea68e26a0d47b5059ee9952e Mon Sep 17 00:00:00 2001

From: Stefan Hajnoczi <stefanha@redhat.com>

Date: Tue, 13 Aug 2013 09:06:36 +0200

Subject: dataplane: enable virtio-blk x-data-plane=on live migration

RH-Author: Stefan Hajnoczi <stefanha@redhat.com>

Message-id: <1376384797-4701-6-git-send-email-stefanha@redhat.com>

Patchwork-id: 53210

O-Subject: [PATCH v2 5/6] dataplane: enable virtio-blk x-data-plane=on live migration

Bugzilla: 995030

RH-Acked-by: Laszlo Ersek <lersek@redhat.com>

RH-Acked-by: Kevin Wolf <kwolf@redhat.com>

RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>

Although the dataplane thread does not cooperate with dirty memory

logging yet it's fairly easy to temporarily disable dataplane during

live migration.  This way virtio-blk can live migrate when

x-data-plane=on.

The dataplane thread will restart after migration is cancelled or if the

guest resuming virtio-blk operation after migration completes.

Reviewed-by: Kevin Wolf <kwolf@redhat.com>

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

(cherry picked from commit 84db52d059f3296abf7783968645c4a96d21b099)

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c

index 2faed43..63c3ffa 100644

--- a/hw/block/dataplane/virtio-blk.c

+++ b/hw/block/dataplane/virtio-blk.c

@@ -18,7 +18,6 @@

 #include "qemu/error-report.h"

 #include "hw/virtio/dataplane/vring.h"

 #include "ioq.h"

-#include "migration/migration.h"

 #include "block/block.h"

 #include "hw/virtio/virtio-blk.h"

 #include "virtio-blk.h"

@@ -69,8 +68,6 @@ struct VirtIOBlockDataPlane {

                                              queue */

     unsigned int num_reqs;

-

-    Error *migration_blocker;

 };

 /* Raise an interrupt to signal guest, if necessary */

@@ -433,10 +430,6 @@ bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,

     /* Prevent block operations that conflict with data plane thread */

     bdrv_set_in_use(blk->conf.bs, 1);

-    error_setg(&s->migration_blocker,

-            "x-data-plane does not support migration");

-    migrate_add_blocker(s->migration_blocker);

-

     *dataplane = s;

     return true;

 }

@@ -448,8 +441,6 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)

     }

     virtio_blk_data_plane_stop(s);

-    migrate_del_blocker(s->migration_blocker);

-    error_free(s->migration_blocker);

     bdrv_set_in_use(s->blk->conf.bs, 0);

     g_free(s);

 }

diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c

index cf12469..cca0c77 100644

--- a/hw/block/virtio-blk.c

+++ b/hw/block/virtio-blk.c

@@ -19,6 +19,7 @@

 #include "hw/virtio/virtio-blk.h"

 #ifdef CONFIG_VIRTIO_BLK_DATA_PLANE

 # include "dataplane/virtio-blk.h"

+# include "migration/migration.h"

 #endif

 #include "block/scsi.h"

 #ifdef __linux__

@@ -628,6 +629,34 @@ void virtio_blk_set_conf(DeviceState *dev, VirtIOBlkConf *blk)

     memcpy(&(s->blk), blk, sizeof(struct VirtIOBlkConf));

 }

+#ifdef CONFIG_VIRTIO_BLK_DATA_PLANE

+/* Disable dataplane thread during live migration since it does not

+ * update the dirty memory bitmap yet.

+ */

+static void virtio_blk_migration_state_changed(Notifier *notifier, void *data)

+{

+    VirtIOBlock *s = container_of(notifier, VirtIOBlock,

+                                  migration_state_notifier);

+    MigrationState *mig = data;

+

+    if (migration_is_active(mig)) {

+        if (!s->dataplane) {

+            return;

+        }

+        virtio_blk_data_plane_destroy(s->dataplane);

+        s->dataplane = NULL;

+    } else if (migration_has_finished(mig) ||

+               migration_has_failed(mig)) {

+        if (s->dataplane) {

+            return;

+        }

+        bdrv_drain_all(); /* complete in-flight non-dataplane requests */

+        virtio_blk_data_plane_create(VIRTIO_DEVICE(s), &s->blk,

+                                     &s->dataplane);

+    }

+}

+#endif /* CONFIG_VIRTIO_BLK_DATA_PLANE */

+

 static int virtio_blk_device_init(VirtIODevice *vdev)

 {

     DeviceState *qdev = DEVICE(vdev);

@@ -664,6 +693,8 @@ static int virtio_blk_device_init(VirtIODevice *vdev)

         virtio_cleanup(vdev);

         return -1;

     }

+    s->migration_state_notifier.notify = virtio_blk_migration_state_changed;

+    add_migration_state_change_notifier(&s->migration_state_notifier);

 #endif

     s->change = qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s);

@@ -683,6 +714,7 @@ static int virtio_blk_device_exit(DeviceState *dev)

     VirtIODevice *vdev = VIRTIO_DEVICE(dev);

     VirtIOBlock *s = VIRTIO_BLK(dev);

 #ifdef CONFIG_VIRTIO_BLK_DATA_PLANE

+    remove_migration_state_change_notifier(&s->migration_state_notifier);

     virtio_blk_data_plane_destroy(s->dataplane);

     s->dataplane = NULL;

 #endif

diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h

index fc71853..b87cf49 100644

--- a/include/hw/virtio/virtio-blk.h

+++ b/include/hw/virtio/virtio-blk.h

@@ -125,6 +125,7 @@ typedef struct VirtIOBlock {

     unsigned short sector_mask;

     VMChangeStateEntry *change;

 #ifdef CONFIG_VIRTIO_BLK_DATA_PLANE

+    Notifier migration_state_notifier;

     struct VirtIOBlockDataPlane *dataplane;

 #endif

 } VirtIOBlock;