Re: [dpdk-dev] [PATCH v4 3/3] net/vhost: fix interrupt mode

["Xia, Chenbo" <chenbo.xia@intel.com>]

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Wednesday, July 29, 2020 9:36 PM
> To: dev@dpdk.org; matan@mellanox.com; Xia, Chenbo
> <chenbo.xia@intel.com>; Liu, Yong <yong.liu@intel.com>; Wang, Yinan
> <yinan.wang@intel.com>
> Cc: thomas@monjalon.net; Yigit, Ferruh <ferruh.yigit@intel.com>;
> david.marchand@redhat.com; Maxime Coquelin
> <maxime.coquelin@redhat.com>
> Subject: [PATCH v4 3/3] net/vhost: fix interrupt mode
> 
> At .new_device() time, only the first vring pair is now ready, other vrings are
> configured later.
> 
> Problem is that when application will setup and enable interrupts, only the first
> queue pair Rx interrupt will be enabled.
> 
> This patches fixes the issue by setting the number of max interrupts to the
> number of Rx queues that will be later initialized. Then, as soon as a Rx vring is
> ready and interrupt enabled by the application, it removes the corresponding
> uninitialized epoll event, and installs a new one with the valid FD.
> 
> Fixes: 604052ae5395 ("net/vhost: support queue update")
> 
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>  drivers/net/vhost/rte_eth_vhost.c | 91 +++++++++++++++++++++++++++----
>  1 file changed, 81 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/vhost/rte_eth_vhost.c
> b/drivers/net/vhost/rte_eth_vhost.c
> index 951929c663..e55278af69 100644
> --- a/drivers/net/vhost/rte_eth_vhost.c
> +++ b/drivers/net/vhost/rte_eth_vhost.c
> @@ -5,6 +5,7 @@
>  #include <unistd.h>
>  #include <pthread.h>
>  #include <stdbool.h>
> +#include <sys/epoll.h>
> 
>  #include <rte_mbuf.h>
>  #include <rte_ethdev_driver.h>
> @@ -95,6 +96,8 @@ struct vhost_queue {
>  	uint16_t port;
>  	uint16_t virtqueue_id;
>  	struct vhost_stats stats;
> +	int intr_enable;
> +	rte_spinlock_t intr_lock;
>  };
> 
>  struct pmd_internal {
> @@ -524,12 +527,58 @@ find_internal_resource(char *ifname)
>  	return list;
>  }
> 
> +static int
> +eth_vhost_update_intr(struct rte_eth_dev *eth_dev, uint16_t rxq_idx) {
> +	struct rte_intr_handle *handle = eth_dev->intr_handle;
> +	struct rte_epoll_event rev;
> +	int epfd, ret;
> +
> +	if (!handle)
> +		return 0;
> +
> +	if (handle->efds[rxq_idx] == handle->elist[rxq_idx].fd)
> +		return 0;
> +
> +	VHOST_LOG(INFO, "kickfd for rxq-%d was changed, updating
> handler.\n",
> +			rxq_idx);
> +
> +	if (handle->elist[rxq_idx].fd != -1)
> +		VHOST_LOG(ERR, "Unexpected previous kickfd value (Got %d,
> expected -1).\n",
> +				handle->elist[rxq_idx].fd);
> +
> +	/*
> +	 * First remove invalid epoll event, and then install
> +	 * the new one. May be solved with a proper API in the
> +	 * future.
> +	 */
> +	epfd = handle->elist[rxq_idx].epfd;
> +	rev = handle->elist[rxq_idx];
> +	ret = rte_epoll_ctl(epfd, EPOLL_CTL_DEL, rev.fd,
> +			&handle->elist[rxq_idx]);
> +	if (ret) {
> +		VHOST_LOG(ERR, "Delete epoll event failed.\n");
> +		return ret;
> +	}
> +
> +	rev.fd = handle->efds[rxq_idx];
> +	handle->elist[rxq_idx] = rev;
> +	ret = rte_epoll_ctl(epfd, EPOLL_CTL_ADD, rev.fd,
> +			&handle->elist[rxq_idx]);
> +	if (ret) {
> +		VHOST_LOG(ERR, "Add epoll event failed.\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
>  static int
>  eth_rxq_intr_enable(struct rte_eth_dev *dev, uint16_t qid)  {
>  	struct rte_vhost_vring vring;
>  	struct vhost_queue *vq;
> -	int ret = 0;
> +	int old_intr_enable, ret = 0;
> 
>  	vq = dev->data->rx_queues[qid];
>  	if (!vq) {
> @@ -537,6 +586,18 @@ eth_rxq_intr_enable(struct rte_eth_dev *dev, uint16_t
> qid)
>  		return -1;
>  	}
> 
> +	rte_spinlock_lock(&vq->intr_lock);
> +	old_intr_enable = vq->intr_enable;
> +	vq->intr_enable = 1;
> +	ret = eth_vhost_update_intr(dev, qid);
> +	rte_spinlock_unlock(&vq->intr_lock);
> +
> +	if (ret < 0) {
> +		VHOST_LOG(ERR, "Failed to update rxq%d's intr\n", qid);
> +		vq->intr_enable = old_intr_enable;
> +		return ret;
> +	}
> +
>  	ret = rte_vhost_get_vhost_vring(vq->vid, (qid << 1) + 1, &vring);
>  	if (ret < 0) {
>  		VHOST_LOG(ERR, "Failed to get rxq%d's vring\n", qid); @@ -
> 571,6 +632,8 @@ 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_enable = 0;
> +
>  	return 0;
>  }
> 
> @@ -593,7 +656,6 @@ eth_vhost_install_intr(struct rte_eth_dev *dev)  {
>  	struct rte_vhost_vring vring;
>  	struct vhost_queue *vq;
> -	int count = 0;
>  	int nb_rxq = dev->data->nb_rx_queues;
>  	int i;
>  	int ret;
> @@ -623,6 +685,8 @@ eth_vhost_install_intr(struct rte_eth_dev *dev)
> 
>  	VHOST_LOG(INFO, "Prepare intr vec\n");
>  	for (i = 0; i < nb_rxq; i++) {
> +		dev->intr_handle->intr_vec[i] = RTE_INTR_VEC_RXTX_OFFSET +
> i;
> +		dev->intr_handle->efds[i] = -1;
>  		vq = dev->data->rx_queues[i];
>  		if (!vq) {
>  			VHOST_LOG(INFO, "rxq-%d not setup yet, skip!\n", i);
> @@ -641,14 +705,12 @@ eth_vhost_install_intr(struct rte_eth_dev *dev)
>  				"rxq-%d's kickfd is invalid, skip!\n", i);
>  			continue;
>  		}
> -		dev->intr_handle->intr_vec[i] = RTE_INTR_VEC_RXTX_OFFSET +
> i;
>  		dev->intr_handle->efds[i] = vring.kickfd;
> -		count++;
>  		VHOST_LOG(INFO, "Installed intr vec for rxq-%d\n", i);
>  	}
> 
> -	dev->intr_handle->nb_efd = count;
> -	dev->intr_handle->max_intr = count + 1;
> +	dev->intr_handle->nb_efd = nb_rxq;
> +	dev->intr_handle->max_intr = nb_rxq + 1;
>  	dev->intr_handle->type = RTE_INTR_HANDLE_VDEV;
> 
>  	return 0;
> @@ -835,6 +897,7 @@ 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 vhost_queue *vq;
>  	struct rte_vhost_vring vring;
>  	int rx_idx = vring_id % 2 ? (vring_id - 1) >> 1 : -1;
>  	int ret = 0;
> @@ -853,12 +916,18 @@ vring_conf_update(int vid, struct rte_eth_dev
> *eth_dev, uint16_t vring_id)
>  					vring_id);
>  			return ret;
>  		}
> +		eth_dev->intr_handle->efds[rx_idx] = vring.kickfd;
> 
> -		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;
> +		vq = eth_dev->data->rx_queues[rx_idx];
> +		if (!vq) {
> +			VHOST_LOG(ERR, "rxq%d is not setup yet\n", rx_idx);
> +			return -1;
>  		}
> +
> +		rte_spinlock_lock(&vq->intr_lock);
> +		if (vq->intr_enable)
> +			ret = eth_vhost_update_intr(eth_dev, rx_idx);
> +		rte_spinlock_unlock(&vq->intr_lock);
>  	}
> 
>  	return ret;
> @@ -1152,6 +1221,7 @@ eth_rx_queue_setup(struct rte_eth_dev *dev,
> uint16_t rx_queue_id,
> 
>  	vq->mb_pool = mb_pool;
>  	vq->virtqueue_id = rx_queue_id * VIRTIO_QNUM + VIRTIO_TXQ;
> +	rte_spinlock_init(&vq->intr_lock);
>  	dev->data->rx_queues[rx_queue_id] = vq;
> 
>  	return 0;
> @@ -1173,6 +1243,7 @@ eth_tx_queue_setup(struct rte_eth_dev *dev,
> uint16_t tx_queue_id,
>  	}
> 
>  	vq->virtqueue_id = tx_queue_id * VIRTIO_QNUM + VIRTIO_RXQ;
> +	rte_spinlock_init(&vq->intr_lock);
>  	dev->data->tx_queues[tx_queue_id] = vq;
> 
>  	return 0;
> --
> 2.26.2

Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>