Re: [Qemu-devel] Re: [PATCH] vhost: fix features ack

[Luiz Capitulino <lcapitulino@redhat.com>]

On Wed, 31 Mar 2010 13:26:23 -0500
Anthony Liguori <anthony@codemonkey.ws> wrote:

> On 03/31/2010 01:20 PM, Michael S. Tsirkin wrote:
> > From: David L Stevens<dlstevens@us.ibm.com>
> >
> > vhost driver in qemu didn't ack features, and this happens
> > to work because we don't really require any features. However,
> > it's better not to rely on this. This patch passes features to
> > vhost as guest acks them.
> >
> > Signed-off-by: David L Stevens<dlstevens@us.ibm.com>
> > Signed-off-by: Michael S. Tsirkin<mst@redhat.com>
> > ---
> >
> > Anthony, here's a fixup patch to address an issue in vhost
> > patches. Incidentially, what's the status of the vhost patchset?
> >    
> 
> http://repo.or.cz/w/qemu/aliguori-queue.git vhost
> 
> Is what I'm currently testing.  With vhost disabled,  the following seg 
> faults:
> 
> qemu-system-x86_64 -hda ~/images/linux.img -net tap -net 
> nic,model=virtio -enable-kvm
> 
> But not when using TCG.  I'm not sure that it's your patches at fault 
> and I'm attempting to bisect now to figure that out.

 Probably this is the same segfault I'm getting right now in master,
bisect says it's:

"""
commit ad96090a01d848df67d70c5259ed8aa321fa8716
Author: Blue Swirl <blauwirbel@gmail.com>
Date:   Mon Mar 29 19:23:52 2010 +0000

    Refactor target specific handling, compile vl.c only once
"""

> 
> Regards,
> 
> Anthony Liguori
> 
> >   hw/virtio-net.c |    8 ++++++++
> >   1 files changed, 8 insertions(+), 0 deletions(-)
> >
> > diff --git a/hw/virtio-net.c b/hw/virtio-net.c
> > index 9ddd58c..4c7c46e 100644
> > --- a/hw/virtio-net.c
> > +++ b/hw/virtio-net.c
> > @@ -218,6 +218,14 @@ static void virtio_net_set_features(VirtIODevice *vdev, uint32_t features)
> >                           (features>>  VIRTIO_NET_F_GUEST_ECN)&  1,
> >                           (features>>  VIRTIO_NET_F_GUEST_UFO)&  1);
> >       }
> > +    if (!n->nic->nc.peer ||
> > +        n->nic->nc.peer->info->type != NET_CLIENT_TYPE_TAP) {
> > +        return;
> > +    }
> > +    if (!tap_get_vhost_net(n->nic->nc.peer)) {
> > +        return;
> > +    }
> > +    return vhost_net_ack_features(tap_get_vhost_net(n->nic->nc.peer), features);
> >   }
> >
> >   static int virtio_net_handle_rx_mode(VirtIONet *n, uint8_t cmd,
> >    
> 
> 
>