Re: [PATCH] failover: unregister ram on unplug

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Jul 21, 2021 at 10:58:17AM +0200, Igor Mammedov wrote:
> On Tue, 20 Jul 2021 20:16:44 +0200
> Laurent Vivier <lvivier@redhat.com> wrote:
> 
> > This simple change allows to test failover with a simulated device
> > like e1000e rather than a vfio device.
> > 
> > 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:
> > 
> >   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
> > 
> > Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> 
> Reviewed-by: Igor Mammedov <imammedo@redhat.com>
> 
> > ---
> >  hw/net/virtio-net.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> > index 16d20cdee52a..8f7735bad4f2 100644
> > --- a/hw/net/virtio-net.c
> > +++ b/hw/net/virtio-net.c
> > @@ -3256,6 +3256,9 @@ static void virtio_net_handle_migration_primary(VirtIONet *n, MigrationState *s)
> >      if (migration_in_setup(s) && !should_be_hidden) {
> >          if (failover_unplug_primary(n, dev)) {
> >              vmstate_unregister(VMSTATE_IF(dev), qdev_get_vmsd(dev), dev);
> > +            if (PCI_DEVICE(dev)->has_rom) {


Hmm. Any way to hide this behind an interface so
we don't need to poke at pci device internals?

> > +                vmstate_unregister_ram(&PCI_DEVICE(dev)->rom , dev);
> > +            }
> >              qapi_event_send_unplug_primary(dev->id);
> >              qatomic_set(&n->failover_primary_hidden, true);
> >          } else {