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qemu/hw/input
Haoqian He bc85aae420 vhost-user: return failure if backend crash when live migration
Live migration should be terminated if the vhost-user backend crashes
before the migration completes.

Specifically, since the vhost device will be stopped when VM is stopped
before the end of the live migration, in current implementation if the
backend crashes, vhost-user device set_status() won't return failure,
live migration won't perceive the disconnection between QEMU and the
backend.

When the VM is migrated to the destination, the inflight IO will be
resubmitted, and if the IO was completed out of order before, it will
cause IO error.

To fix this issue:
1. Add the return value to set_status() for VirtioDeviceClass.
  a. For the vhost-user device, return failure when the backend crashes.
  b. For other virtio devices, always return 0.
2. Return failure if vhost_dev_stop() failed for vhost-user device.

If QEMU loses connection with the vhost-user backend, virtio set_status()
can return failure to the upper layer, migration_completion() can handle
the error, terminate the live migration, and restore the VM, so that
inflight IO can be completed normally.

Signed-off-by: Haoqian He <haoqian.he@smartx.com>
Message-Id: <20250416024729.3289157-4-haoqian.he@smartx.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2 months ago
..
Kconfig hw/input: Remove lm832x device 9 months ago
adb-internal.h
adb-kbd.c qom: Have class_init() take a const data argument 2 months ago
adb-mouse.c qom: Have class_init() take a const data argument 2 months ago
adb.c qom: Have class_init() take a const data argument 2 months ago
hid.c
lasips2.c qom: Have class_init() take a const data argument 2 months ago
meson.build hw/input: Remove lm832x device 9 months ago
pckbd.c qom: Make InterfaceInfo[] uses const 2 months ago
pl050.c qom: Have class_init() take a const data argument 2 months ago
ps2.c qom: Have class_init() take a const data argument 2 months ago
stellaris_gamepad.c qom: Have class_init() take a const data argument 2 months ago
trace-events
trace.h
virtio-input-hid.c qom: Have class_init() take a const data argument 2 months ago
virtio-input-host.c qom: Have class_init() take a const data argument 2 months ago
virtio-input.c vhost-user: return failure if backend crash when live migration 2 months ago