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

[Juan Quintela]

Laurent Vivier <lvivier@redhat.com> wrote:
> 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>

Reviewed-by: Juan Quintela <quintela@redhat.com>

One could even defend that unpluging the device and *NOT* unpluging the
ROM is a bug, independently of failover, no?

Later, Juan.