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authorDima Stepanov2020-09-11 10:39:43 +0200
committerMichael S. Tsirkin2020-09-29 08:14:29 +0200
commitf5b22d06fb0526c9292568dd1fc13b9d1a8b003e (patch)
treec5bf20b6e2d544af22315b36d241f19eac2c65f9 /hw/virtio
parentpc: fix auto_enable_numa_with_memhp/auto_enable_numa_with_memdev for the 5.0 ... (diff)
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vhost: recheck dev state in the vhost_migration_log routine
vhost-user devices can get a disconnect in the middle of the VHOST-USER handshake on the migration start. If disconnect event happened right before sending next VHOST-USER command, then the vhost_dev_set_log() call in the vhost_migration_log() function will return error. This error will lead to the assert() and close the QEMU migration source process. For the vhost-user devices the disconnect event should not break the migration process, because: - the device will be in the stopped state, so it will not be changed during migration - if reconnect will be made the migration log will be reinitialized as part of reconnect/init process: #0 vhost_log_global_start (listener=0x563989cf7be0) at hw/virtio/vhost.c:920 #1 0x000056398603d8bc in listener_add_address_space (listener=0x563989cf7be0, as=0x563986ea4340 <address_space_memory>) at softmmu/memory.c:2664 #2 0x000056398603dd30 in memory_listener_register (listener=0x563989cf7be0, as=0x563986ea4340 <address_space_memory>) at softmmu/memory.c:2740 #3 0x0000563985fd6956 in vhost_dev_init (hdev=0x563989cf7bd8, opaque=0x563989cf7e30, backend_type=VHOST_BACKEND_TYPE_USER, busyloop_timeout=0) at hw/virtio/vhost.c:1385 #4 0x0000563985f7d0b8 in vhost_user_blk_connect (dev=0x563989cf7990) at hw/block/vhost-user-blk.c:315 #5 0x0000563985f7d3f6 in vhost_user_blk_event (opaque=0x563989cf7990, event=CHR_EVENT_OPENED) at hw/block/vhost-user-blk.c:379 Update the vhost-user-blk device with the internal started_vu field which will be used for initialization (vhost_user_blk_start) and clean up (vhost_user_blk_stop). This additional flag in the VhostUserBlk structure will be used to track whether the device really needs to be stopped and cleaned up on a vhost-user level. The disconnect event will set the overall VHOST device (not vhost-user) to the stopped state, so it can be used by the general vhost_migration_log routine. Such approach could be propogated to the other vhost-user devices, but better idea is just to make the same connect/disconnect code for all the vhost-user devices. This migration issue was slightly discussed earlier: - https://lists.gnu.org/archive/html/qemu-devel/2020-05/msg01509.html - https://lists.gnu.org/archive/html/qemu-devel/2020-05/msg05241.html Signed-off-by: Dima Stepanov <dimastep@yandex-team.ru> Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com> Message-Id: <9fbfba06791a87813fcee3e2315f0b904cc6789a.1599813294.git.dimastep@yandex-team.ru> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'hw/virtio')
-rw-r--r--hw/virtio/vhost.c27
1 files changed, 24 insertions, 3 deletions
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 8087f200e9..60bc516003 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -871,21 +871,42 @@ static int vhost_migration_log(MemoryListener *listener, bool enable)
dev->log_enabled = enable;
return 0;
}
+
+ r = 0;
if (!enable) {
r = vhost_dev_set_log(dev, false);
if (r < 0) {
- return r;
+ goto check_dev_state;
}
vhost_log_put(dev, false);
} else {
vhost_dev_log_resize(dev, vhost_get_log_size(dev));
r = vhost_dev_set_log(dev, true);
if (r < 0) {
- return r;
+ goto check_dev_state;
}
}
+
+check_dev_state:
dev->log_enabled = enable;
- return 0;
+ /*
+ * vhost-user-* devices could change their state during log
+ * initialization due to disconnect. So check dev state after
+ * vhost communication.
+ */
+ if (!dev->started) {
+ /*
+ * Since device is in the stopped state, it is okay for
+ * migration. Return success.
+ */
+ r = 0;
+ }
+ if (r) {
+ /* An error is occured. */
+ dev->log_enabled = false;
+ }
+
+ return r;
}
static void vhost_log_global_start(MemoryListener *listener)