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

[Yuanhan Liu]

On Tue, Oct 27, 2015 at 04:28:58PM +0900, Tetsuya Mukawa wrote:
> Hi Yuanhan,
> 
> I appreciate your checking.

Welcome! And thank you for catching out my faults.

	--yliu
> I haven't noticed SET_BACKEND is only supported by vhost-cuse. :-(
> I will follow your comments, then submit again.
> 
> Thanks,
> Tetsuya
> 
> On 2015/10/27 15:47, Yuanhan Liu wrote:
> > 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