We find an issue when host mce trigger openvswitch(dpdk) restart in source host
during guest migration,
VM is still link down in frontend after migration, it cause the network in VM
never be up again.
virtio_net_load_device:
/* nc.link_down can't be migrated, so infer link_down according
* to link status bit in n->status */
link_down = (n->status & VIRTIO_NET_S_LINK_UP) == 0;
for (i = 0; i < n->max_queues; i++) {
qemu_get_subqueue(n->nic, i)->link_down = link_down;
}
guset: migrate begin -------> vCPU pause --------> vmsate
load ------->migrate finish
^ ^
^
| |
|
openvswitch in source host: begin to restart restarting
started
^ ^
^
| |
|
nc in frontend in source: link down link down
link down
^ ^
^
| |
|
nc in frontend in destination: link up link up
link down
^ ^
^
| |
|
guset network: broken broken
broken
^ ^
^
| |
|
nc in backend in source: link down link down
link up
^ ^
^
| |
|
nc in backend in destination: link up link up
link up
The link_down of frontend was loaded from n->status, n->status is link down in
source, so the link_down of
frontend is true. The backend in destination host is link up, but the frontend
in destination host is
link down, it cause the network in gust never be up again until an guest cold
reboot.
Is there a way to auto fix the link status? or just abort the migration in
virtio net device load?
