[dpdk-stable] [PATCH] vhost: fix silent queue enabling with legacy guests

[Ilya Maximets]

vhost should notify the application in case of all vring state changes.

In general, application should not care about negotiation of
VHOST_USER_F_PROTOCOL_FEATURES. Protocol details like this should
be hidden by the vhost library.

With this patch applications like OVS will be able to assume that
all vrings disabled by default and only process 'vring_state_changed'
events.

Fixes: 321203a54ba7 ("vhost: enable rings at the right time")
Cc: stable at dpdk.org

Signed-off-by: Ilya Maximets <i.maximets at samsung.com>
---
 lib/librte_vhost/vhost_user.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index 23beed97d..c9e29ece8 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -1231,8 +1231,12 @@ vhost_user_set_vring_kick(struct virtio_net **pdev, struct VhostUserMsg *msg,
 	 * the ring starts already enabled. Otherwise, it is enabled via
 	 * the SET_VRING_ENABLE message.
 	 */
-	if (!(dev->features & (1ULL << VHOST_USER_F_PROTOCOL_FEATURES)))
+	if (!(dev->features & (1ULL << VHOST_USER_F_PROTOCOL_FEATURES))) {
 		vq->enabled = 1;
+		if (dev->notify_ops->vring_state_changed)
+			dev->notify_ops->vring_state_changed(
+				dev->vid, file.index, 1);
+	}
 
 	if (vq->kickfd >= 0)
 		close(vq->kickfd);
-- 
2.17.1