On Wed, Nov 09, 2016 at 05:22:02PM +0200, yuri.benditov...@daynix.com wrote:
> From: Yuri Benditovich <yuri.benditov...@daynix.com>
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1295637
> Upon set_link monitor command or upon netdev deletion
> virtio-net sends link down indication to the guest
> and stops vhost if one is used.
> Guest driver can still submit data for TX until it
> recognizes link loss. If these packets not returned by
> the host, the Windows guest will never be able to finish
> disable/removal/shutdown.
> Now each packet sent by guest after NIC indicated link
> down will be completed immediately.
>
> Signed-off-by: Yuri Benditovich <yuri.benditov...@daynix.com>
> ---
> hw/net/virtio-net.c | 28 ++++++++++++++++++++++++++++
> 1 file changed, 28 insertions(+)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 06bfe4b..ab4e18a 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -218,6 +218,16 @@ static void virtio_net_vnet_endian_status(VirtIONet *n,
> uint8_t status)
> }
> }
>
> +static void virtio_net_drop_tx_queue_data(VirtIODevice *vdev, VirtQueue *vq)
> +{
> + VirtQueueElement *elem;
> + while ((elem = virtqueue_pop(vq, sizeof(VirtQueueElement)))) {
> + virtqueue_push(vq, elem, 0);
> + virtio_notify(vdev, vq);
> + g_free(elem);
> + }
> +}
> +
> static void virtio_net_set_status(struct VirtIODevice *vdev, uint8_t status)
> {
> VirtIONet *n = VIRTIO_NET(vdev);
I don't like this part. This does too much queue parsing,
I would like to just copy head from avail to used ring.
For example, people want to support rings >1K in size.
Let's add bool virtqueue_drop(vq) and be done with it.
> @@ -262,6 +272,14 @@ static void virtio_net_set_status(struct VirtIODevice
> *vdev, uint8_t status)
> } else {
> qemu_bh_cancel(q->tx_bh);
> }
> + if ((n->status & VIRTIO_NET_S_LINK_UP) == 0 &&
> + (queue_status & VIRTIO_CONFIG_S_DRIVER_OK)) {
> + /* if tx is waiting we are likely have some packets in tx
> queue
> + * and disabled notification */
> + q->tx_waiting = 0;
> + virtio_queue_set_notification(q->tx_vq, 1);
> + virtio_net_drop_tx_queue_data(vdev, q->tx_vq);
> + }
> }
> }
> }
OK but what if guest keeps sending packets? What will drop them?
> @@ -1319,6 +1337,11 @@ static void virtio_net_handle_tx_timer(VirtIODevice
> *vdev, VirtQueue *vq)
> VirtIONet *n = VIRTIO_NET(vdev);
> VirtIONetQueue *q = &n->vqs[vq2q(virtio_get_queue_index(vq))];
>
> + if (unlikely((n->status & VIRTIO_NET_S_LINK_UP) == 0)) {
> + virtio_net_drop_tx_queue_data(vdev, vq);
> + return;
> + }
> +
> /* This happens when device was stopped but VCPU wasn't. */
> if (!vdev->vm_running) {
> q->tx_waiting = 1;
> @@ -1345,6 +1368,11 @@ static void virtio_net_handle_tx_bh(VirtIODevice
> *vdev, VirtQueue *vq)
> VirtIONet *n = VIRTIO_NET(vdev);
> VirtIONetQueue *q = &n->vqs[vq2q(virtio_get_queue_index(vq))];
>
> + if (unlikely((n->status & VIRTIO_NET_S_LINK_UP) == 0)) {
> + virtio_net_drop_tx_queue_data(vdev, vq);
> + return;
> + }
> +
> if (unlikely(q->tx_waiting)) {
> return;
> }
> --
> 1.9.1
