Re: [Qemu-devel] [PATCH v2] net: Add support of VIRTIO_NET_F_GUEST_ANNOUNCE for vhost-net/vhost-user

[Michael S. Tsirkin]

On Mon, Jun 08, 2015 at 04:13:59PM +0100, Stefan Hajnoczi wrote:
> On Mon, Jun 8, 2015 at 3:05 PM, Thibaut Collet <address@hidden> wrote:
> >> I think Jason is pointing out that your patch lacks support for guests
> >> that do not negotiate VIRTIO_NET_F_GUEST_ANNOUNCE.
> >
> > I have understood the issue with old guest pointed by Jason.
> > I have thinking about the best way to do solve it and any advices are
> > welcome.
> 
> 1. Add vhost-user virtio-net command to inject packets
> 
> Add a new VhostUserRequest VHOST_USER_NET_INJECT_PACKET allowing QEMU
> to hand a packet to the vhost-user process for injection.  This
> command is virtio-net specific and fails if called on a different
> device type.
> 
> 2. Fail negotiation when VIRTIO_NET_F_GUEST_ANNOUNCE is not accepted
> 
> This is only really possible in VIRTIO 1.0 and later.  Pre-1.0 does
> not allow the device to reject due to disabled features.
> 
> file:///home/stefanha/virtio/trunk/virtio-v1.0-cs02.html#x1-450001
> 
> Therefore this is not a great solution.
> 
> 3. The easiest solution - nop .receive()
> 
> Just implement a nop .receive() which drops the packet and prints a
> warning message to stderr.  This way VIRTIO_NET_F_GUEST_ANNOUNCE
> guests work while legacy guests don't send a gratuitous ARP packet.
> 
> Stefan

3 sounds good to me.

-- 
MST