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

Yuanhan Liu yuanhan.liu at linux.intel.com
Tue Oct 27 07:33:28 CET 2015


On Tue, Oct 27, 2015 at 02:29:25PM +0800, 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.
> 
> No, that's not right, we will get GET_VRING_BASE for each queue pair,
> including RX and TX virt queue, but not each virt queue.

Oops, you are right, and I was right in the first time till
Huawei pointted out that I made some unexpected change, and
I then checked the code, I then made a wrong decison (a
bit too tired recently :(

So, I will look at this patch, again.

Sorry for that.

	--yliu
> 
> > 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.
> > 
> > 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;
> 
> For the Nth queue (pair), the "state->index" equals to  N * 2.
> So, dividing it by VIRTIO_QNUM (2) is wrong here.
> 
> 	--yliu
> 
> >  
> >  	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);
> > +
> >  	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;
> >  	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;
> >  
> >  	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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