qemu/hw/block
Dima Stepanov f5b22d06fb 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>
2020-09-29 02:14:29 -04:00
..
dataplane meson: convert hw/block 2020-08-21 06:30:32 -04:00
Kconfig hw/m68k: add a dummy SWIM floppy controller 2019-10-28 19:06:51 +01:00
block.c block: make BlockConf size props 32bit and accept size suffixes 2020-06-17 14:53:40 +02:00
cdrom.c Include qemu-common.h exactly where needed 2019-06-12 13:20:20 +02:00
ecc.c Include hw/hw.h exactly where needed 2019-08-16 13:31:52 +02:00
fdc.c Use OBJECT_DECLARE_SIMPLE_TYPE when possible 2020-09-18 14:12:32 -04:00
hd-geometry.c block: Remove blk_pread_unthrottled() 2019-08-16 10:25:16 +02:00
m25p80.c Use OBJECT_DECLARE_TYPE when possible 2020-09-18 14:12:32 -04:00
meson.build meson: convert hw/block 2020-08-21 06:30:32 -04:00
nand.c Use OBJECT_DECLARE_SIMPLE_TYPE when possible 2020-09-18 14:12:32 -04:00
nvme.c hw/block/nvme: remove explicit qsg/iov parameters 2020-09-02 08:48:50 +02:00
nvme.h hw/block/nvme: add ns/cmd references in NvmeRequest 2020-09-02 08:48:50 +02:00
onenand.c Use OBJECT_DECLARE_SIMPLE_TYPE when possible 2020-09-18 14:12:32 -04:00
pflash_cfi01.c hw: Remove superfluous breaks 2020-09-01 08:38:00 +02:00
pflash_cfi02.c pflash: Use ERRP_GUARD() 2020-07-10 15:18:09 +02:00
swim.c swim: Rename struct SWIM to Swim 2020-08-27 14:04:55 -04:00
tc58128.c Include hw/hw.h exactly where needed 2019-08-16 13:31:52 +02:00
trace-events trace-events: Fix attribution of trace points to source 2020-09-09 17:17:58 +01:00
trace.h trace: switch position of headers to what Meson requires 2020-08-21 06:18:24 -04:00
vhost-user-blk.c vhost: recheck dev state in the vhost_migration_log routine 2020-09-29 02:14:29 -04:00
virtio-blk.c virtio-blk: undo destructive iov_discard_*() operations 2020-09-23 13:41:58 +01:00
xen-block.c xen: Use ERRP_GUARD() 2020-07-10 15:18:09 +02:00
xen_blkif.h xen: Import other xen/io/*.h 2019-06-24 10:42:30 +01:00