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Re: [Qemu-devel] [PATCH] virtio-net: remove virtio queues if the guest d
From: |
Jason Wang |
Subject: |
Re: [Qemu-devel] [PATCH] virtio-net: remove virtio queues if the guest doesn't support multiqueue |
Date: |
Wed, 15 Jul 2015 14:59:41 +0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 |
On 07/15/2015 02:23 PM, Wen Congyang wrote:
> commit da51a335 adds all queues in .realize(). But if the
> guest doesn't support multiqueue, we forget to remove them. And
> we cannot handle the ctrl vq corretly. The guest will hang.
>
> Signed-off-by: Wen Congyang <address@hidden>
Thanks for the patch, some questions, see below.
> ---
> hw/net/virtio-net.c | 69
> +++++++++++++++++++++++++++++++++++++++++------------
> 1 file changed, 54 insertions(+), 15 deletions(-)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index e3c2db3..658806a 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -1306,9 +1306,62 @@ static void virtio_net_tx_bh(void *opaque)
> }
> }
>
> +static void virtio_net_add_queue(VirtIONet *n, int index)
> +{
> + VirtIODevice *vdev = VIRTIO_DEVICE(n);
> +
> + n->vqs[index].rx_vq = virtio_add_queue(vdev, 256, virtio_net_handle_rx);
> + if (n->net_conf.tx && !strcmp(n->net_conf.tx, "timer")) {
> + n->vqs[index].tx_vq =
> + virtio_add_queue(vdev, 256, virtio_net_handle_tx_timer);
> + n->vqs[index].tx_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
> + virtio_net_tx_timer,
> + &n->vqs[index]);
> + } else {
> + n->vqs[index].tx_vq =
> + virtio_add_queue(vdev, 256, virtio_net_handle_tx_bh);
> + n->vqs[index].tx_bh = qemu_bh_new(virtio_net_tx_bh, &n->vqs[index]);
> + }
> +
> + n->vqs[index].tx_waiting = 0;
> + n->vqs[index].n = n;
> +}
> +
> +static void virtio_net_change_num_queues(VirtIONet *n, int new_max_queues)
> +{
> + VirtIODevice *vdev = VIRTIO_DEVICE(n);
> + int old_num_queues = virtio_get_num_queues(vdev);
> + int new_num_queues = new_max_queues * 2 + 1;
> + int i;
> +
> + assert(old_num_queues >= 3);
> + assert(old_num_queues % 2 == 1);
> +
> + if (old_num_queues == new_num_queues) {
> + return;
> + }
> +
> + /* Remove ctrl_vq first */
> + virtio_del_queue(vdev, old_num_queues - 1);
Why ctrl vq must be first to be deleted?
> +
> + for (i = new_num_queues - 1; i < old_num_queues - 1; i++) {
> + virtio_del_queue(vdev, i);
Do we need to delete bh and timer also here?
> + }
> +
> + for (i = old_num_queues - 1; i < new_num_queues - 1; i += 2) {
> + virtio_net_add_queue(n, i / 2);
> + }
> +
> + /* add ctrl_vq last */
> + n->ctrl_vq = virtio_add_queue(vdev, 64, virtio_net_handle_ctrl);
> +}
> +
> static void virtio_net_set_multiqueue(VirtIONet *n, int multiqueue)
> {
> + int max = multiqueue ? n->max_queues : 1;
> +
> n->multiqueue = multiqueue;
> + virtio_net_change_num_queues(n, max);
>
> virtio_net_set_queues(n);
> }
> @@ -1583,21 +1636,7 @@ static void virtio_net_device_realize(DeviceState
> *dev, Error **errp)
> }
>
> for (i = 0; i < n->max_queues; i++) {
> - n->vqs[i].rx_vq = virtio_add_queue(vdev, 256, virtio_net_handle_rx);
> - if (n->net_conf.tx && !strcmp(n->net_conf.tx, "timer")) {
> - n->vqs[i].tx_vq =
> - virtio_add_queue(vdev, 256, virtio_net_handle_tx_timer);
> - n->vqs[i].tx_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
> - virtio_net_tx_timer,
> - &n->vqs[i]);
> - } else {
> - n->vqs[i].tx_vq =
> - virtio_add_queue(vdev, 256, virtio_net_handle_tx_bh);
> - n->vqs[i].tx_bh = qemu_bh_new(virtio_net_tx_bh, &n->vqs[i]);
> - }
> -
> - n->vqs[i].tx_waiting = 0;
> - n->vqs[i].n = n;
> + virtio_net_add_queue(n, i);
> }
>
> n->ctrl_vq = virtio_add_queue(vdev, 64, virtio_net_handle_ctrl);