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vfio/migration: Don't emit STOP_COPY VFIO migration QAPI event twice

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When migrating a VFIO device that supports pre-copy, it is transitioned
to STOP_COPY twice: once in vfio_vmstate_change() and second time in
vfio_save_complete_precopy().

The second transition is harmless, as it's a STOP_COPY->STOP_COPY no-op
transition. However, with the newly added VFIO migration QAPI event, the
STOP_COPY event is undesirably emitted twice.

Prevent this by returning early in vfio_migration_set_state() if
new_state is the same as current device state.

Note that the STOP_COPY transition in vfio_save_complete_precopy() is
essential for VFIO devices that don't support pre-copy, for migrating an
already stopped guest and for snapshots.

Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
This commit is contained in:
Avihai Horon 2024-05-15 16:21:37 +03:00 committed by Cédric Le Goater
parent 5e1f8905ca
commit 64366eddf1
1 changed files with 4 additions and 0 deletions
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4
hw/vfio/migration.c
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@ -150,6 +150,10 @@ static int vfio_migration_set_state(VFIODevice *vbasedev,
g_strdup_printf("%s: Failed setting device state to %s.",
vbasedev->name, mig_state_to_str(new_state));
if (new_state == migration->device_state) {
return 0;
}
feature->argsz = sizeof(buf);
feature->flags =
VFIO_DEVICE_FEATURE_SET | VFIO_DEVICE_FEATURE_MIG_DEVICE_STATE;