Re: [dpdk-dev] [PATCH v2] net/vhost: support queue update

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

Thanks Matan for the fix.

On 7/21/20 6:38 PM, Matan Azrad wrote:
> The commit below changed the readiness condition of vhost device to fix
> multi-queues issues showed with QEMU versions.
> 
> Now, the vhost device is ready when the first queue-pair is ready.
> When more queues are being ready, the queue state callback will be
> triggered to notify the vhost manager.
> 
> In case of Rx interrupt configuration, the vhost driver set the
> kickfd queue file descriptor in order to be notified on Rx traffic.
> 
> So, when queue becomes ready, the kickfd may be changed and should be
> updated in the Rx interrupt structure.
> 
> Update kickfd when the queue state callback is invoked.
> Also update event notification when it is enabled by the user.
> 
> Fixes: d0fcc38f5fa4 ("vhost: improve device readiness notifications")
> 
> Signed-off-by: Matan Azrad <matan@mellanox.com>
> ---
>  drivers/net/vhost/rte_eth_vhost.c | 49 +++++++++++++++++++++++++++++++
>  1 file changed, 49 insertions(+)
> 
> diff --git a/drivers/net/vhost/rte_eth_vhost.c b/drivers/net/vhost/rte_eth_vhost.c
> index 9fbf39f66b..bbf79b2c0e 100644
> --- a/drivers/net/vhost/rte_eth_vhost.c
> +++ b/drivers/net/vhost/rte_eth_vhost.c
> @@ -94,6 +94,7 @@ struct vhost_queue {
>  	struct rte_mempool *mb_pool;
>  	uint16_t port;
>  	uint16_t virtqueue_id;
> +	bool intr_en;
>  	struct vhost_stats stats;
>  };
>  
> @@ -546,6 +547,8 @@ eth_rxq_intr_enable(struct rte_eth_dev *dev, uint16_t qid)
>  	rte_vhost_enable_guest_notification(vq->vid, (qid << 1) + 1, 1);
>  	rte_wmb();
>  
> +	vq->intr_en = true;
> +
>  	return ret;
>  }
>  
> @@ -571,6 +574,8 @@ eth_rxq_intr_disable(struct rte_eth_dev *dev, uint16_t qid)
>  	rte_vhost_enable_guest_notification(vq->vid, (qid << 1) + 1, 0);
>  	rte_wmb();
>  
> +	vq->intr_en = false;
> +
>  	return 0;
>  }
>  
> @@ -830,6 +835,45 @@ destroy_device(int vid)
>  	_rte_eth_dev_callback_process(eth_dev, RTE_ETH_EVENT_INTR_LSC, NULL);
>  }
>  
> +static int
> +vring_conf_update(int vid, struct rte_eth_dev *eth_dev, uint16_t vring_id)
> +{
> +	struct rte_eth_conf *dev_conf = &eth_dev->data->dev_conf;
> +	struct pmd_internal *internal = eth_dev->data->dev_private;
> +	struct rte_vhost_vring vring;
> +	struct vhost_queue *vq;
> +	int rx_idx = vring_id % 2 ? (vring_id - 1) >> 1 : -1;
> +	int ret = 0;
> +
> +	/*
> +	 * The vring kickfd may be changed after the new device notification.
> +	 * Update it when the vring state is updated.
> +	 */
> +	if (rx_idx >= 0 && rx_idx < eth_dev->data->nb_rx_queues &&
> +	    rte_atomic32_read(&internal->dev_attached) &&
> +	    rte_atomic32_read(&internal->started) &&
> +	    dev_conf->intr_conf.rxq) {

I am not sure we need to filter on rxq, we could just call
rte_vhost_enable_guest_notification(). It would be disabled for tx
queues, as it is done in the .new_device callback so harmless and this
function would be simpler.

But I think your code work, so we should get it in -rc2 to get proper
testing:

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

Thanks,
Maxime

> +		vq = eth_dev->data->rx_queues[rx_idx];
> +		ret = rte_vhost_get_vhost_vring(vid, vring_id, &vring);
> +		if (!ret) {
> +			if (vring.kickfd !=
> +			    eth_dev->intr_handle->efds[rx_idx]) {
> +				VHOST_LOG(INFO,
> +					  "kickfd for rxq-%d was changed.\n",
> +					  rx_idx);
> +				eth_dev->intr_handle->efds[rx_idx] =
> +								   vring.kickfd;
> +			}
> +
> +			rte_vhost_enable_guest_notification(vid, vring_id,
> +							    vq->intr_en);
> +			rte_wmb();
> +		}
> +	}
> +
> +	return ret;
> +}
> +
>  static int
>  vring_state_changed(int vid, uint16_t vring, int enable)
>  {
> @@ -848,6 +892,11 @@ vring_state_changed(int vid, uint16_t vring, int enable)
>  	eth_dev = list->eth_dev;
>  	/* won't be NULL */
>  	state = vring_states[eth_dev->data->port_id];
> +
> +	if (enable && vring_conf_update(vid, eth_dev, vring))
> +		VHOST_LOG(INFO, "Failed to update vring-%d configuration.\n",
> +			  (int)vring);
> +
>  	rte_spinlock_lock(&state->lock);
>  	if (state->cur[vring] == enable) {
>  		rte_spinlock_unlock(&state->lock);
>