[dpdk-dev] [PATCH v2 3/3] net/vhost: fix interrupt mode

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

At .new_device() time, only the first vring pair is
now ready, other vrings are consfigured 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,
it removes the corresponding uninitialized epoll event,
and install 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 | 39 ++++++++++++++++++++++++++-----
 1 file changed, 33 insertions(+), 6 deletions(-)

diff --git a/drivers/net/vhost/rte_eth_vhost.c b/drivers/net/vhost/rte_eth_vhost.c
index 951929c663..0f6a0bbbf7 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>
@@ -593,7 +594,6 @@ 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 +623,8 @@ 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 +643,12 @@ 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;
@@ -836,8 +836,11 @@ 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 rte_intr_handle *handle;
+	struct rte_epoll_event rev;
 	int rx_idx = vring_id % 2 ? (vring_id - 1) >> 1 : -1;
 	int ret = 0;
+	int epfd;
 
 	/*
 	 * The vring kickfd may be changed after the new device notification.
@@ -857,7 +860,31 @@ vring_conf_update(int vid, struct rte_eth_dev *eth_dev, uint16_t vring_id)
 		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;
+
+			/*
+			 * First remove invalid epoll event, and then isntall
+			 * the new one. May be solved with a proper API in the
+			 * future.
+			 */
+			handle = eth_dev->intr_handle;
+			handle->efds[rx_idx] = vring.kickfd;
+			epfd = handle->elist[rx_idx].epfd;
+			rev = handle->elist[rx_idx];
+			ret = rte_epoll_ctl(epfd, EPOLL_CTL_DEL, rev.fd,
+					&handle->elist[rx_idx]);
+			if (ret) {
+				VHOST_LOG(ERR, "Delete epoll event failed.\n");
+				return ret;
+			}
+
+			rev.fd = vring.kickfd;
+			handle->elist[rx_idx] = rev;
+			ret = rte_epoll_ctl(epfd, EPOLL_CTL_ADD, rev.fd,
+					&handle->elist[rx_idx]);
+			if (ret) {
+				VHOST_LOG(ERR, "Add epoll event failed.\n");
+				return ret;
+			}
 		}
 	}
 
-- 
2.26.2