[dpdk-dev] [PATCH v4] vhost: add support for interrupt mode

[Junjie Chen <junjie.j.chen@intel.com>]

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>
---
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 | 167 ++++++++++++++++++++++++++++++++++++--
 lib/librte_vhost/vhost.c          |  13 ++-
 2 files changed, 164 insertions(+), 16 deletions(-)

diff --git a/drivers/net/vhost/rte_eth_vhost.c b/drivers/net/vhost/rte_eth_vhost.c
index 11b6076..9a23c12 100644
--- a/drivers/net/vhost/rte_eth_vhost.c
+++ b/drivers/net/vhost/rte_eth_vhost.c
@@ -554,28 +554,174 @@ update_queuing_status(struct rte_eth_dev *dev)
 	}
 }
 
+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 int
 queue_setup(struct rte_eth_dev *eth_dev, struct pmd_internal *internal)
 {
 	struct vhost_queue *vq;
+	struct rte_eth_conf *dev_conf = &eth_dev->data->dev_conf;
+	int vid = internal->vid;
 	int i;
 
 	for (i = 0; i < eth_dev->data->nb_rx_queues; i++) {
 		vq = eth_dev->data->rx_queues[i];
 		if (!vq)
 			continue;
-		vq->vid = internal->vid;
+		vq->vid = vid;
 		vq->internal = internal;
 		vq->port = eth_dev->data->port_id;
 	}
+
 	for (i = 0; i < eth_dev->data->nb_tx_queues; i++) {
 		vq = eth_dev->data->tx_queues[i];
 		if (!vq)
 			continue;
-		vq->vid = internal->vid;
+		vq->vid = vid;
 		vq->internal = internal;
 		vq->port = eth_dev->data->port_id;
 	}
+
+	for (i = 0; i < rte_vhost_get_vring_num(vid); i++)
+		rte_vhost_enable_guest_notification(vid, i, 0);
+
+	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;
+		}
+	}
+
+	return 0;
 }
 
 static int
@@ -584,7 +730,6 @@ new_device(int vid)
 	struct rte_eth_dev *eth_dev;
 	struct internal_list *list;
 	struct pmd_internal *internal;
-	unsigned i;
 	char ifname[PATH_MAX];
 #ifdef RTE_LIBRTE_VHOST_NUMA
 	int newnode;
@@ -608,16 +753,13 @@ new_device(int vid)
 
 	internal->vid = vid;
 	if (eth_dev->data->rx_queues && eth_dev->data->tx_queues) {
-		queue_setup(eth_dev, internal);
-		rte_atomic32_set(&internal->dev_attached, 1);
+		if (!queue_setup(eth_dev, internal))
+			rte_atomic32_set(&internal->dev_attached, 1);
 	} else {
 		RTE_LOG(INFO, PMD, "RX/TX queues have not setup yet\n");
 		rte_atomic32_set(&internal->dev_attached, 0);
 	}
 
-	for (i = 0; i < rte_vhost_get_vring_num(vid); i++)
-		rte_vhost_enable_guest_notification(vid, i, 0);
-
 	rte_vhost_get_mtu(vid, &eth_dev->data->mtu);
 
 	eth_dev->data->dev_link.link_status = ETH_LINK_UP;
@@ -681,6 +823,8 @@ destroy_device(int vid)
 
 	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);
 }
 
@@ -793,7 +937,10 @@ eth_dev_start(struct rte_eth_dev *eth_dev)
 	struct pmd_internal *internal = eth_dev->data->dev_private;
 
 	if (unlikely(rte_atomic32_read(&internal->dev_attached) == 0)) {
-		queue_setup(eth_dev, internal);
+		if (!queue_setup(eth_dev, internal)) {
+			RTE_LOG(ERR, PMD, "Failed to set up rx queue\n");
+			return -1;
+		}
 		rte_atomic32_set(&internal->dev_attached, 1);
 	}
 
@@ -1030,6 +1177,8 @@ 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..68e9340 100644
--- a/lib/librte_vhost/vhost.c
+++ b/lib/librte_vhost/vhost.c
@@ -545,16 +545,15 @@ rte_vhost_enable_guest_notification(int vid, uint16_t queue_id, int enable)
 {
 	struct virtio_net *dev = get_device(vid);
 
-	if (dev == NULL)
+	if (!dev)
 		return -1;
 
-	if (enable) {
-		RTE_LOG(ERR, VHOST_CONFIG,
-			"guest notification isn't supported.\n");
-		return -1;
-	}
+	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;
 
-	dev->virtqueue[queue_id]->used->flags = VRING_USED_F_NO_NOTIFY;
 	return 0;
 }
 
-- 
2.0.1