[libvirt] [PATCH v2] qemu: handle multicast overflow on macvtap NIC_RX_FILTER_CHANGED

[Michael S. Tsirkin]

On Mon, Dec 03, 2018 at 01:52:45PM +0100, Michal Privoznik wrote:
> On 11/30/18 6:50 PM, Jason Baron wrote:
> > Guest network devices can set 'overflow' when there are a number of multicast
> > ips configured. For virtio_net, the limit is only 64. In this case, the list
> > of mac addresses is empty and the 'overflow' condition is set. Thus, the guest
> > will currently receive no multicast traffic in this state.
> > 
> > When 'overflow' is set in the guest, let's turn this into ALLMULTI on the host.
> > 
> > Signed-off-by: Jason Baron <jbaron at akamai.com>
> > ---
> > v1->v2:
> >  1. check for < 0 in virNetDevSetRcvAllMulti() (Michal Privoznik)
> >  2. restrict overflow check to VIR_NETDEV_RX_FILTER_MODE_NORMAL mode as to
> >     avoid unnecessarily calling rx filter updates for other modes 
> >  3. update virNetDevSetRcvAllMulti() call to use guestFilter->multicast.overflow
> >     directly (Michal Privoznik)
> > 
> >  src/qemu/qemu_driver.c | 22 +++++++++++++++-------
> >  1 file changed, 15 insertions(+), 7 deletions(-)
> 
> ACK
> 
> We're currently in a freeze. While this is a bug fix I'm not sure it's
> that critical. The freeze should be over any minute now, so do you mind
> if I merge it after that?
> 
> Michal

FYI It's a blocker for some people as multicast stops working completely.

-- 
MST