[Qemu-devel] [PATCH] libvhost-user: Start VQs on SET_VRING_CALL

[Felipe Franciosi <felipe@nutanix.com>]

Currently, VQs are started as soon as a SET_VRING_KICK is received. That
is too early in the VQ setup process, as the backend might not yet have
a callfd to notify in case it received a kick and fully processed the
request/command. This patch only starts a VQ when a SET_VRING_CALL is
received.

Signed-off-by: Felipe Franciosi <felipe@nutanix.com>
---
 contrib/libvhost-user/libvhost-user.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
index af4faad..a46ef90 100644
--- a/contrib/libvhost-user/libvhost-user.c
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -607,19 +607,6 @@ vu_set_vring_kick_exec(VuDev *dev, VhostUserMsg *vmsg)
         DPRINT("Got kick_fd: %d for vq: %d\n", vmsg->fds[0], index);
     }
 
-    dev->vq[index].started = true;
-    if (dev->iface->queue_set_started) {
-        dev->iface->queue_set_started(dev, index, true);
-    }
-
-    if (dev->vq[index].kick_fd != -1 && dev->vq[index].handler) {
-        dev->set_watch(dev, dev->vq[index].kick_fd, VU_WATCH_IN,
-                       vu_kick_cb, (void *)(long)index);
-
-        DPRINT("Waiting for kicks on fd: %d for vq: %d\n",
-               dev->vq[index].kick_fd, index);
-    }
-
     return false;
 }
 
@@ -661,6 +648,19 @@ vu_set_vring_call_exec(VuDev *dev, VhostUserMsg *vmsg)
 
     DPRINT("Got call_fd: %d for vq: %d\n", vmsg->fds[0], index);
 
+    dev->vq[index].started = true;
+    if (dev->iface->queue_set_started) {
+        dev->iface->queue_set_started(dev, index, true);
+    }
+
+    if (dev->vq[index].kick_fd != -1 && dev->vq[index].handler) {
+        dev->set_watch(dev, dev->vq[index].kick_fd, VU_WATCH_IN,
+                       vu_kick_cb, (void *)(long)index);
+
+        DPRINT("Waiting for kicks on fd: %d for vq: %d\n",
+               dev->vq[index].kick_fd, index);
+    }
+
     return false;
 }
 
-- 
1.9.4