Comment 7 for bug 1944619

what i suspect has happend here is the live migration fails in the migration phase
after pre_live_migrate

in that case in most case setting the vm to error is actully the expected outcome.
we can role back in some case but we do not garunetee that roleback will happen in migrate.

i suspect that the reason connectivity is lost is because the failure to migrate due to a vm on the destination using the incorrect VF happens in driver.live_migration after we have unpluged the pci devices form the source vm which takes use to the _rollback_live_migration codepath but that has two outcomes. it can set teh vm to error or in limited cases rollback and leave the vm running on the source node unaffected by the failed live migration.

https://docs.openstack.org/nova/latest/reference/live-migration.html

in this case i suspect we don reattech the VF to the vm.