On Tue, Jun 09, 2026 at 10:58:06AM +0300, Avihai Horon wrote: > Switchover ACK is checked only during precopy while the guest is still > running. The last migration_can_switchover() decision and guest stop are > not atomic, so a device may want to request another switchover ACK in > the gap after switchover decision has been made but before the guest is > stopped. Migration would then miss that request, which can increase > downtime. > > Cover this case by failing the migration if a switchover-ack was > requested during that time. > > Ideally, precopy iterations should be resumed in this case, however, > VFIO doesn't support going back to precopy after being stopped, so > implementing such logic would require non-trivial changes to the guest > start/stop flow. Given the above and that this case should be rare, > failing the migration seems reasonable. > > Signed-off-by: Avihai Horon <[email protected]>
Reviewed-by: Peter Xu <[email protected]> -- Peter Xu
