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

[Anthony Liguori]

On 03/31/2010 01:20 PM, Michael S. Tsirkin wrote:
> From: David L Stevens<address@hidden>
>
> 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<address@hidden>
> Signed-off-by: Michael S. Tsirkin<address@hidden>
> ---
>
> 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.

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,
>