[dpdk-dev] [PATCH] vhost: postpone ring addresses translations at kick time only

[Maxime Coquelin]

If multiple queue pairs are created but all are not used, the
device is never started, as unused queues aren't enabled and
their ring addresses aren't translated. The device is changed
to running state when all rings addresses are translated.

This patch fixes this by postponning rings addresses translation
at kick time unconditionnaly, VHOST_USER_F_PROTOCOL_FEATURES
being negotiated or not.

Reported-by: Lei Yao <lei.a.yao at intel.com>
Signed-off-by: Maxime Coquelin <maxime.coquelin at redhat.com>
---
 lib/librte_vhost/vhost_user.c | 33 ++++++++-------------------------
 1 file changed, 8 insertions(+), 25 deletions(-)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index 1f6cba4b9..849755093 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -755,15 +755,12 @@ vhost_user_set_vring_kick(struct virtio_net **pdev, struct VhostUserMsg *pmsg)
 	RTE_LOG(INFO, VHOST_CONFIG,
 		"vring kick idx:%d file:%d\n", file.index, file.fd);
 
-	/*
-	 * Interpret ring addresses only when ring is started and enabled.
-	 * This is now if protocol features aren't supported.
-	 */
-	if (!(dev->features & (1ULL << VHOST_USER_F_PROTOCOL_FEATURES))) {
-		*pdev = dev = translate_ring_addresses(dev, file.index);
-		if (!dev)
-			return;
-	}
+	/* Interpret ring addresses only when ring is started. */
+	dev = translate_ring_addresses(dev, file.index);
+	if (!dev)
+		return;
+
+	*pdev = dev;
 
 	vq = dev->virtqueue[file.index];
 
@@ -845,29 +842,15 @@ vhost_user_get_vring_base(struct virtio_net *dev,
  * enable the virtio queue pair.
  */
 static int
-vhost_user_set_vring_enable(struct virtio_net **pdev,
+vhost_user_set_vring_enable(struct virtio_net *dev,
 			    VhostUserMsg *msg)
 {
-	struct virtio_net *dev = *pdev;
 	int enable = (int)msg->payload.state.num;
 
 	RTE_LOG(INFO, VHOST_CONFIG,
 		"set queue enable: %d to qp idx: %d\n",
 		enable, msg->payload.state.index);
 
-	/*
-	 * Interpret ring addresses only when ring is started and enabled.
-	 * This is now if protocol features are supported.
-	 */
-	if (enable && (dev->features &
-				(1ULL << VHOST_USER_F_PROTOCOL_FEATURES))) {
-		dev = translate_ring_addresses(dev, msg->payload.state.index);
-		if (!dev)
-			return -1;
-
-		*pdev = dev;
-	}
-
 	if (dev->notify_ops->vring_state_changed)
 		dev->notify_ops->vring_state_changed(dev->vid,
 				msg->payload.state.index, enable);
@@ -1315,7 +1298,7 @@ vhost_user_msg_handler(int vid, int fd)
 		break;
 
 	case VHOST_USER_SET_VRING_ENABLE:
-		vhost_user_set_vring_enable(&dev, &msg);
+		vhost_user_set_vring_enable(dev, &msg);
 		break;
 	case VHOST_USER_SEND_RARP:
 		vhost_user_send_rarp(dev, &msg);
-- 
2.13.6