On Mon, Dec 11, 2017 at 04:15:03PM +0100, Maxime Coquelin wrote:
> QEMU sends VHOST_USER_SET_VRING_CALL requests for all queues
> declared in QEMU command line before the guest is started.
> It has the effect in DPDK vhost-user backend to allocate vrings
> for all queues declared by QEMU.
>
> If the first driver being used does not support multiqueue,
> the device never changes to VIRTIO_DEV_RUNNING state as only
> the first queue pair is initialized. One driver impacted by
> this bug is virtio-net's iPXE driver which does not support
> VIRTIO_NET_F_MQ feature.
>
> It is safe to destroy unused virtqueues in SET_FEATURES request
> handler, as it is ensured the device is not in running state
> at this stage, so virtqueues aren't being processed.
>
> Signed-off-by: Maxime Coquelin <maxime.coque...@redhat.com>
> ---
> lib/librte_vhost/vhost_user.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index 471b1612c..d5ca1ac90 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -216,6 +216,24 @@ vhost_user_set_features(struct virtio_net *dev, uint64_t
> features)
> (dev->features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ? "on" : "off",
> (dev->features & (1ULL << VIRTIO_F_VERSION_1)) ? "on" : "off");
>
> + if (!(dev->features & (1ULL << VIRTIO_NET_F_MQ))) {
> + /*
> + * Remove all but first queue pair if MQ hasn't been
> + * negotiated. This is safe because the device is not
> + * running at this stage.
> + */
> + while (dev->nr_vring > 2) {
> + struct vhost_virtqueue *vq;
> +
> + vq = dev->virtqueue[--dev->nr_vring];
> + if (!vq)
> + continue;
> +
> + cleanup_vq(vq, 1);
> + free_vq(vq);
Hi,
Sorry, I didn't look into this patch in last version.
The freed dev->virtqueue[$idx] also needs to be zeroed.
Otherwise, it won't be allocated in the future due to the
below check in vhost_user_check_and_alloc_queue_pair(),
and the freed memory will be used again.
/*
* Allocate a queue pair if it hasn't been allocated yet
*/
static int
vhost_user_check_and_alloc_queue_pair(struct virtio_net *dev, VhostUserMsg *msg)
{
........
if (dev->virtqueue[vring_idx])
return 0;
return alloc_vring_queue(dev, vring_idx);
}
Best regards,
Tiwei Bie
> + }
> + }
> +
> return 0;
> }
>
> --
> 2.14.3
>
