Re: [dpdk-dev] [PATCH v2 2/5] vhost: improve device readiness notifications

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 6/25/20 3:38 PM, Matan Azrad wrote:
> Some guest drivers may not configure disabled virtio queues.
> 
> In this case, the vhost management never notifies the application and
> the vDPA device readiness because it waits to the device to be ready.
> 
> The current ready state means that all the virtio queues should be
> configured regardless the enablement status.
> 
> In order to support this case, this patch changes the ready state:
> The device is ready when at least 1 queue pair is configured and
> enabled.
> 
> So, now, the application and vDPA driver are notifies when the first
> queue pair is configured and enabled.
> 
> Also the queue notifications will be triggered according to the new
> ready definition.
> 
> Signed-off-by: Matan Azrad <matan@mellanox.com>
> ---
>  lib/librte_vhost/vhost.h      |  1 +
>  lib/librte_vhost/vhost_user.c | 55 +++++++++++++++++++++++++++++--------------
>  2 files changed, 38 insertions(+), 18 deletions(-)
> 
> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
> index 17f1e9a..8a74f33 100644
> --- a/lib/librte_vhost/vhost.h
> +++ b/lib/librte_vhost/vhost.h
> @@ -151,6 +151,7 @@ struct vhost_virtqueue {
>  	int			backend;
>  	int			enabled;
>  	int			access_ok;
> +	int			ready;
>  	rte_spinlock_t		access_lock;
>  
>  	/* Used to notify the guest (trigger interrupt) */
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index 8d8050b..b90fc78 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -228,6 +228,21 @@
>  	dev->postcopy_listening = 0;
>  }
>  
> +static void
> +vhost_user_notify_queue_state(struct virtio_net *dev, uint16_t index,
> +			      int enable)
> +{
> +	int did = dev->vdpa_dev_id;
> +	struct rte_vdpa_device *vdpa_dev = rte_vdpa_get_device(did);
> +
> +	if (vdpa_dev && vdpa_dev->ops->set_vring_state)
> +		vdpa_dev->ops->set_vring_state(dev->vid, index, enable);
> +
> +	if (dev->notify_ops->vring_state_changed)
> +		dev->notify_ops->vring_state_changed(dev->vid,
> +				index, enable);
> +}
> +
>  /*
>   * This function just returns success at the moment unless
>   * the device hasn't been initialised.
> @@ -1306,27 +1321,31 @@
>  
>  	return rings_ok &&
>  	       vq->kickfd != VIRTIO_UNINITIALIZED_EVENTFD &&
> -	       vq->callfd != VIRTIO_UNINITIALIZED_EVENTFD;
> +	       vq->callfd != VIRTIO_UNINITIALIZED_EVENTFD &&
> +	       vq->enabled;
>  }
>  
> +#define VIRTIO_DEV_NUM_VQS_TO_BE_READY 2u

(Thinking out loud) If for some reason it would cause issue with OVS-
DPDK or other application, it should be easy to only apply this new way
of initializing the device based on whether vdpa device is attached or
not.

>  static int
>  virtio_is_ready(struct virtio_net *dev)
>  {
>  	struct vhost_virtqueue *vq;
>  	uint32_t i;
>  
> -	if (dev->nr_vring == 0)
> +	if (dev->nr_vring < VIRTIO_DEV_NUM_VQS_TO_BE_READY)
>  		return 0;
>  
> -	for (i = 0; i < dev->nr_vring; i++) {
> +	for (i = 0; i < VIRTIO_DEV_NUM_VQS_TO_BE_READY; i++) {
>  		vq = dev->virtqueue[i];
>  
>  		if (!vq_is_ready(dev, vq))
>  			return 0;
>  	}
>  
> -	VHOST_LOG_CONFIG(INFO,
> -		"virtio is now ready for processing.\n");
> +	if (!(dev->flags & VIRTIO_DEV_RUNNING))
> +		VHOST_LOG_CONFIG(INFO,
> +			"virtio is now ready for processing.\n");
>  	return 1;
>  }


Patch looks good to me, thanks for working on it.


Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Maxime