Re: [Qemu-devel] [PATCH v3 1/5] virtio_net: Add VIRTIO_NET_F_STANDBY feature bit.

[Samudrala, Sridhar]

On 1/8/2019 4:14 PM, Dongli Zhang wrote:
> Hi Venu,
>
> On 2019/1/9 上午1:25, Venu Busireddy wrote:
> > On 2019-01-09 00:56:38 +0800, Dongli Zhang wrote:
> > > I am not familiar with libvirt and I would like to play with this only with 
> > > qemu.
> > >
> > > With failover, we need to hotplug the VF on destination server to VM after live
> > > migration. However, the VF on destination server would have different mac 
> > > address.
> > >
> > > How can we specify the mac for the new VF to hotplug via qemu, as VF is only a
> > > vfio pci device?
> > How is the VF device on the destination host any different from the VF
> > on the source host?
> >
> > As you do on the source host, you first assign the MAC address of
> > 00:00:00:00:00:00 to the VF. After the migration, you assign the same
> > MAC address as that of the virtio_net device to the VF, and hotadd the VF
> This was what I was wondering.
>
> How the mac address is configured for VF (or any NIC like PF) after it is
> assigned to vfio?

ip link set <pf> vf  <vf-num>  mac <MAC>

See https://www.kernel.org/doc/html/latest/networking/net_failover.html
for a sample script that shows the steps to initiate live migration with VF
and virtio-net in standby mode.


> Thank you very much!
>
> Dongli Zhang
>
>
> > device to the VM. And then, after you receive the FAILOVER_PRIMARY_CHANGED
> > event, set the macvtap device to down state.
> >
> > Venu
> >
> > > I am trying to play with this with only qemu (w/o libvirt).
> > >
> > > Thank you very much!
> > >
> > > Dongli Zhang
> > >
> > > On 01/08/2019 06:29 AM, Venu Busireddy wrote:
> > > > From: Sridhar Samudrala <address@hidden>
> > > >
> > > > This feature bit can be used by a hypervisor to indicate to the virtio_net
> > > > device that it can act as a standby for another device with the same MAC
> > > > address.
> > > >
> > > > Signed-off-by: Sridhar Samudrala <address@hidden>
> > > > Signed-off-by: Venu Busireddy <address@hidden>
> > > > ---
> > > >   hw/net/virtio-net.c | 2 ++
> > > >   1 file changed, 2 insertions(+)
> > > >
> > > > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> > > > index 385b1a0..411f8fb 100644
> > > > --- a/hw/net/virtio-net.c
> > > > +++ b/hw/net/virtio-net.c
> > > > @@ -2198,6 +2198,8 @@ static Property virtio_net_properties[] = {
> > > >                        true),
> > > >       DEFINE_PROP_INT32("speed", VirtIONet, net_conf.speed, SPEED_UNKNOWN),
> > > >       DEFINE_PROP_STRING("duplex", VirtIONet, net_conf.duplex_str),
> > > > +    DEFINE_PROP_BIT64("standby", VirtIONet, host_features, 
> > > > VIRTIO_NET_F_STANDBY,
> > > > +                      false),
> > > >       DEFINE_PROP_END_OF_LIST(),
> > > >   };
> > > >