[dpdk-dev] [PATCH 1/3] vhost: Fix wrong handling of virtqueue array index

Yuanhan Liu yuanhan.liu at linux.intel.com
Tue Oct 27 07:47:20 CET 2015


On Tue, Oct 27, 2015 at 03:12:53PM +0900, Tetsuya Mukawa wrote:
> The patch fixes wrong handling of virtqueue array index.
> 
> GET_VRING_BASE:
> The vhost backend will receive the message per virtqueue.
> Also we should call a destroy callback when both RXQ and TXQ receives
> the message.
> 
> SET_BACKEND:
> Because vhost library supports multiple queue, the index may be over 2.
> Also a vhost frontend(QEMU) may send such a index.

Note that only vhost-user supports MQ. vhost-cuse does not.

> Signed-off-by: Tetsuya Mukawa <mukawa at igel.co.jp>
> ---
>  lib/librte_vhost/vhost_user/virtio-net-user.c | 22 +++++++++++-----------
>  lib/librte_vhost/virtio-net.c                 |  5 +++--
>  2 files changed, 14 insertions(+), 13 deletions(-)
> 
> diff --git a/lib/librte_vhost/vhost_user/virtio-net-user.c b/lib/librte_vhost/vhost_user/virtio-net-user.c
> index a998ad8..3e8dfea 100644
> --- a/lib/librte_vhost/vhost_user/virtio-net-user.c
> +++ b/lib/librte_vhost/vhost_user/virtio-net-user.c
> @@ -283,12 +283,10 @@ user_get_vring_base(struct vhost_device_ctx ctx,
>  	struct vhost_vring_state *state)
>  {
>  	struct virtio_net *dev = get_device(ctx);
> +	uint16_t base_idx = state->index / VIRTIO_QNUM;

So, fixing what my 1st reply said, for Nth queue pair, state->index
is "N * 2 + is_tx". So, the base should be "state->index / 2 * 2".

>  
>  	if (dev == NULL)
>  		return -1;
> -	/* We have to stop the queue (virtio) if it is running. */
> -	if (dev->flags & VIRTIO_DEV_RUNNING)
> -		notify_ops->destroy_device(dev);
>  
>  	/* Here we are safe to get the last used index */
>  	ops->get_vring_base(ctx, state->index, state);
> @@ -300,15 +298,17 @@ user_get_vring_base(struct vhost_device_ctx ctx,
>  	 * sent and only sent in vhost_vring_stop.
>  	 * TODO: cleanup the vring, it isn't usable since here.
>  	 */
> -	if (dev->virtqueue[state->index + VIRTIO_RXQ]->kickfd >= 0) {
> -		close(dev->virtqueue[state->index + VIRTIO_RXQ]->kickfd);
> -		dev->virtqueue[state->index + VIRTIO_RXQ]->kickfd = -1;
> -	}
> -	if (dev->virtqueue[state->index + VIRTIO_TXQ]->kickfd >= 0) {
> -		close(dev->virtqueue[state->index + VIRTIO_TXQ]->kickfd);
> -		dev->virtqueue[state->index + VIRTIO_TXQ]->kickfd = -1;
> +	if (dev->virtqueue[state->index]->kickfd >= 0) {
> +		close(dev->virtqueue[state->index]->kickfd);
> +		dev->virtqueue[state->index]->kickfd = -1;
>  	}
>  
> +	/* We have to stop the queue (virtio) if it is running. */
> +	if ((dev->flags & VIRTIO_DEV_RUNNING) &&
> +			(dev->virtqueue[base_idx + VIRTIO_RXQ]->kickfd == -1) &&
> +			(dev->virtqueue[base_idx + VIRTIO_TXQ]->kickfd == -1))
> +		notify_ops->destroy_device(dev);

This is a proper fix then. (You just need fix base_idx).

>  	return 0;
>  }
>  
> @@ -321,7 +321,7 @@ user_set_vring_enable(struct vhost_device_ctx ctx,
>  		      struct vhost_vring_state *state)
>  {
>  	struct virtio_net *dev = get_device(ctx);
> -	uint16_t base_idx = state->index;
> +	uint16_t base_idx = state->index / VIRTIO_QNUM;

user_set_vring_enable is sent per queue pair (I'm sure this time), so
base_idx equals to state->index. No need fix here.

>  	int enable = (int)state->num;
>  
>  	RTE_LOG(INFO, VHOST_CONFIG,
> diff --git a/lib/librte_vhost/virtio-net.c b/lib/librte_vhost/virtio-net.c
> index 97213c5..ee2e84d 100644
> --- a/lib/librte_vhost/virtio-net.c
> +++ b/lib/librte_vhost/virtio-net.c
> @@ -778,6 +778,7 @@ static int
>  set_backend(struct vhost_device_ctx ctx, struct vhost_vring_file *file)
>  {
>  	struct virtio_net *dev;
> +	uint32_t base_idx = file->index / VIRTIO_QNUM;

As stated, vhost-cuse doesn't not support MQ.

	--yliu
>  
>  	dev = get_device(ctx);
>  	if (dev == NULL)
> @@ -791,8 +792,8 @@ set_backend(struct vhost_device_ctx ctx, struct vhost_vring_file *file)
>  	 * we add the device.
>  	 */
>  	if (!(dev->flags & VIRTIO_DEV_RUNNING)) {
> -		if (((int)dev->virtqueue[VIRTIO_TXQ]->backend != VIRTIO_DEV_STOPPED) &&
> -			((int)dev->virtqueue[VIRTIO_RXQ]->backend != VIRTIO_DEV_STOPPED)) {
> +		if (((int)dev->virtqueue[base_idx + VIRTIO_RXQ]->backend != VIRTIO_DEV_STOPPED) &&
> +			((int)dev->virtqueue[base_idx + VIRTIO_TXQ]->backend != VIRTIO_DEV_STOPPED)) {
>  			return notify_ops->new_device(dev);
>  		}
>  	/* Otherwise we remove it. */
> -- 
> 2.1.4


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