Re: [dpdk-dev] [PATCH v6 1/2] vhost: add support for interrupt mode

["Tan, Jianfeng" <jianfeng.tan@intel.com>]

On 4/13/2018 12:28 AM, Junjie Chen wrote:
> In some cases we want vhost dequeue work in interrupt mode to
> release cpus to others when no data to transmit. So we install
> interrupt handler of vhost device and interrupt vectors for each
> rx queue when creating new backend according to vhost intrerupt
> configuration. Thus, applications could register a epoll event fd
> to associate rx queues with interrupt vectors.
>
> Signed-off-by: Junjie Chen <junjie.j.chen@intel.com>

Reviewed-by: Jianfeng Tan <jianfeng.tan@intel.com>

> ---
> Changes in v6:
> - rebase code to master
> Changes in v5:
> - update license to DPDK new license format
> - rebase code to master
> Changes in v4:
> - revert back license change
> Changes in v3:
> - handle failure in the middle of intr setup.
> - use vhost API to enable interrupt.
> - rebase to check rxq existence.
> - update vhost API to support guest notification.
> Changes in v2:
> - update rx queue index.
> - fill efd_counter_size for intr handler.
> - update log.
>   drivers/net/vhost/rte_eth_vhost.c | 158 +++++++++++++++++++++++++++++++++++++-
>   lib/librte_vhost/vhost.c          |  14 ++--
>   2 files changed, 163 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/vhost/rte_eth_vhost.c b/drivers/net/vhost/rte_eth_vhost.c
> index e392d71..8b4b716 100644
> --- a/drivers/net/vhost/rte_eth_vhost.c
> +++ b/drivers/net/vhost/rte_eth_vhost.c
> @@ -520,6 +520,136 @@ find_internal_resource(char *ifname)
>   	return list;
>   }
>   
> +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;
> +
> +	vq = dev->data->rx_queues[qid];
> +	if (!vq) {
> +		RTE_LOG(ERR, PMD, "rxq%d is not setup yet\n", qid);
> +		return -1;
> +	}
> +
> +	ret = rte_vhost_get_vhost_vring(vq->vid, (qid << 1) + 1, &vring);
> +	if (ret < 0) {
> +		RTE_LOG(ERR, PMD, "Failed to get rxq%d's vring\n", qid);
> +		return ret;
> +	}
> +	RTE_LOG(INFO, PMD, "Enable interrupt for rxq%d\n", qid);
> +	rte_vhost_enable_guest_notification(vq->vid, (qid << 1) + 1, 1);
> +	rte_wmb();
> +
> +	return ret;
> +}
> +
> +static int
> +eth_rxq_intr_disable(struct rte_eth_dev *dev, uint16_t qid)
> +{
> +	struct rte_vhost_vring vring;
> +	struct vhost_queue *vq;
> +	int ret = 0;
> +
> +	vq = dev->data->rx_queues[qid];
> +	if (!vq) {
> +		RTE_LOG(ERR, PMD, "rxq%d is not setup yet\n", qid);
> +		return -1;
> +	}
> +
> +	ret = rte_vhost_get_vhost_vring(vq->vid, (qid << 1) + 1, &vring);
> +	if (ret < 0) {
> +		RTE_LOG(ERR, PMD, "Failed to get rxq%d's vring", qid);
> +		return ret;
> +	}
> +	RTE_LOG(INFO, PMD, "Disable interrupt for rxq%d\n", qid);
> +	rte_vhost_enable_guest_notification(vq->vid, (qid << 1) + 1, 0);
> +	rte_wmb();
> +
> +	return 0;
> +}
> +
> +static void
> +eth_vhost_uninstall_intr(struct rte_eth_dev *dev)
> +{
> +	struct rte_intr_handle *intr_handle = dev->intr_handle;
> +
> +	if (intr_handle) {
> +		if (intr_handle->intr_vec)
> +			free(intr_handle->intr_vec);
> +		free(intr_handle);
> +	}
> +
> +	dev->intr_handle = NULL;
> +}
> +
> +static int
> +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;
> +
> +	/* uninstall firstly if we are reconnecting */
> +	if (dev->intr_handle)
> +		eth_vhost_uninstall_intr(dev);
> +
> +	dev->intr_handle = malloc(sizeof(*dev->intr_handle));
> +	if (!dev->intr_handle) {
> +		RTE_LOG(ERR, PMD, "Fail to allocate intr_handle\n");
> +		return -ENOMEM;
> +	}
> +	memset(dev->intr_handle, 0, sizeof(*dev->intr_handle));
> +
> +	dev->intr_handle->efd_counter_size = sizeof(uint64_t);
> +
> +	dev->intr_handle->intr_vec =
> +		malloc(nb_rxq * sizeof(dev->intr_handle->intr_vec[0]));
> +
> +	if (!dev->intr_handle->intr_vec) {
> +		RTE_LOG(ERR, PMD,
> +			"Failed to allocate memory for interrupt vector\n");
> +		free(dev->intr_handle);
> +		return -ENOMEM;
> +	}
> +
> +	RTE_LOG(INFO, PMD, "Prepare intr vec\n");
> +	for (i = 0; i < nb_rxq; i++) {
> +		vq = dev->data->rx_queues[i];
> +		if (!vq) {
> +			RTE_LOG(INFO, PMD, "rxq-%d not setup yet, skip!\n", i);
> +			continue;
> +		}
> +
> +		ret = rte_vhost_get_vhost_vring(vq->vid, (i << 1) + 1, &vring);
> +		if (ret < 0) {
> +			RTE_LOG(INFO, PMD,
> +				"Failed to get rxq-%d's vring, skip!\n", i);
> +			continue;
> +		}
> +
> +		if (vring.kickfd < 0) {
> +			RTE_LOG(INFO, PMD,
> +				"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++;
> +		RTE_LOG(INFO, PMD, "Installed intr vec for rxq-%d\n", i);
> +	}
> +
> +	dev->intr_handle->nb_efd = count;
> +	dev->intr_handle->max_intr = count + 1;
> +	dev->intr_handle->type = RTE_INTR_HANDLE_VDEV;
> +
> +	return 0;
> +}
> +
>   static void
>   update_queuing_status(struct rte_eth_dev *dev)
>   {
> @@ -585,6 +715,7 @@ new_device(int vid)
>   	struct rte_eth_dev *eth_dev;
>   	struct internal_list *list;
>   	struct pmd_internal *internal;
> +	struct rte_eth_conf *dev_conf;
>   	unsigned i;
>   	char ifname[PATH_MAX];
>   #ifdef RTE_LIBRTE_VHOST_NUMA
> @@ -600,6 +731,7 @@ new_device(int vid)
>   
>   	eth_dev = list->eth_dev;
>   	internal = eth_dev->data->dev_private;
> +	dev_conf = &eth_dev->data->dev_conf;
>   
>   #ifdef RTE_LIBRTE_VHOST_NUMA
>   	newnode = rte_vhost_get_numa_node(vid);
> @@ -608,8 +740,17 @@ new_device(int vid)
>   #endif
>   
>   	internal->vid = vid;
> -	if (rte_atomic32_read(&internal->started) == 1)
> +	if (rte_atomic32_read(&internal->started) == 1) {
>   		queue_setup(eth_dev, internal);
> +
> +		if (dev_conf->intr_conf.rxq) {
> +			if (eth_vhost_install_intr(eth_dev) < 0) {
> +				RTE_LOG(INFO, PMD,
> +					"Failed to install interrupt handler.");
> +					return -1;
> +			}
> +		}
> +	}
>   	else
>   		RTE_LOG(INFO, PMD, "RX/TX queues not exist yet\n");
>   
> @@ -680,6 +821,7 @@ destroy_device(int vid)
>   	rte_spinlock_unlock(&state->lock);
>   
>   	RTE_LOG(INFO, PMD, "Vhost device %d destroyed\n", vid);
> +	eth_vhost_uninstall_intr(eth_dev);
>   
>   	_rte_eth_dev_callback_process(eth_dev, RTE_ETH_EVENT_INTR_LSC, NULL);
>   }
> @@ -791,8 +933,20 @@ static int
>   eth_dev_start(struct rte_eth_dev *eth_dev)
>   {
>   	struct pmd_internal *internal = eth_dev->data->dev_private;
> +	struct rte_eth_conf *dev_conf = &eth_dev->data->dev_conf;
>   
>   	queue_setup(eth_dev, internal);
> +	
> +	if (rte_atomic32_read(&internal->dev_attached) == 1) {
> +		if (dev_conf->intr_conf.rxq) {
> +			if (eth_vhost_install_intr(eth_dev) < 0) {
> +				RTE_LOG(INFO, PMD,
> +					"Failed to install interrupt handler.");
> +					return -1;
> +			}
> +		}
> +	}
> +
>   	rte_atomic32_set(&internal->started, 1);
>   	update_queuing_status(eth_dev);
>   
> @@ -1029,6 +1183,8 @@ static const struct eth_dev_ops ops = {
>   	.xstats_reset = vhost_dev_xstats_reset,
>   	.xstats_get = vhost_dev_xstats_get,
>   	.xstats_get_names = vhost_dev_xstats_get_names,
> +	.rx_queue_intr_enable = eth_rxq_intr_enable,
> +	.rx_queue_intr_disable = eth_rxq_intr_disable,
>   };
>   
>   static struct rte_vdev_driver pmd_vhost_drv;
> diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
> index f6f12a0..10f795f 100644
> --- a/lib/librte_vhost/vhost.c
> +++ b/lib/librte_vhost/vhost.c
> @@ -545,16 +545,14 @@ rte_vhost_enable_guest_notification(int vid, uint16_t queue_id, int enable)
>   {
>   	struct virtio_net *dev = get_device(vid);
>   
> -	if (dev == NULL)
> -		return -1;
> -
> -	if (enable) {
> -		RTE_LOG(ERR, VHOST_CONFIG,
> -			"guest notification isn't supported.\n");
> +	if (!dev)
>   		return -1;
> -	}
>   
> -	dev->virtqueue[queue_id]->used->flags = VRING_USED_F_NO_NOTIFY;
> +	if (enable)
> +		dev->virtqueue[queue_id]->used->flags &=
> +			~VRING_USED_F_NO_NOTIFY;
> +	else	
> +		dev->virtqueue[queue_id]->used->flags |= VRING_USED_F_NO_NOTIFY;
>   	return 0;
>   }
>