[RFC PATCH v2 6/8] failover: pci: unregister ROM on unplug

[Laurent Vivier]

The intend of failover is to allow a VM with a VFIO networking card to
be migrated without disrupting the network operation by switching
to a virtio-net device during the migration.

This simple change allows a simulated device like e1000e to be tested
rather than a vfio device, even if it's useless in real life it can help
to debug failover.

This is interesting to developers that want to test failover on
a system with no vfio device. Moreover it simplifies host networking
configuration as we can use the same bridge for virtio-net and
the other failover networking device.

Without this change the migration of a system configured with failover
fails with:

  ...
  -device virtio-net-pci,id=virtionet0,failover=on,...  \
  -device e1000,failover_pair_id=virtionet0,... \
  ...

  (qemu) migrate ...

  Unknown ramblock "0000:00:01.1:00.0/e1000e.rom", cannot accept migration
  error while loading state for instance 0x0 of device 'ram'
  load of migration failed: Invalid argument

This happens because QEMU correctly unregisters the interface vmstate but
not the ROM one. This patch fixes that.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
 hw/pci/pci.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index dd5e95216abf..10b875fdfad1 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -2208,6 +2208,7 @@ static void pci_dev_handle_migration(PCIDevice *pci_dev, 
MigrationState *s)
     if (migration_in_setup(s)) {
         if (pci_dev_migration_unplug(pci_dev)) {
             vmstate_unregister(VMSTATE_IF(dev), qdev_get_vmsd(dev), dev);
+            pci_del_option_rom(pci_dev);
             qapi_event_send_unplug_primary(dev->id);
         } else {
             warn_report("couldn't unplug primary device");
-- 
2.31.1