[PATCH V2 15/18] vhost-net: control virtqueue support

[Jason Wang <jasowang@redhat.com>]

We assume there's no cvq in the past, this is not true when we need
control virtqueue support for vhost-user backends. So this patch
implements the control virtqueue support for vhost-net. As datapath,
the control virtqueue is also required to be coupled with the
NetClientState. The vhost_net_start/stop() are tweaked to accept the
number of datapath queue pairs plus the the number of control
virtqueue for us to start and stop the vhost device.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 hw/net/vhost_net.c      | 43 ++++++++++++++++++++++++++++++-----------
 hw/net/virtio-net.c     |  4 ++--
 include/net/vhost_net.h |  6 ++++--
 3 files changed, 38 insertions(+), 15 deletions(-)

diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index ef1370bd92..4294fb9fc9 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -311,11 +311,14 @@ static void vhost_net_stop_one(struct vhost_net *net,
 }
 
 int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
-                    int total_queues)
+                    int data_qps, int cvq)
 {
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(dev)));
     VirtioBusState *vbus = VIRTIO_BUS(qbus);
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
+    int total_notifiers = data_qps * 2 + cvq;
+    VirtIONet *n = VIRTIO_NET(dev);
+    int nvhosts = data_qps + cvq;
     struct vhost_net *net;
     int r, e, i;
     NetClientState *peer;
@@ -325,9 +328,14 @@ int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
         return -ENOSYS;
     }
 
-    for (i = 0; i < total_queues; i++) {
+    for (i = 0; i < nvhosts; i++) {
+
+        if (i < data_qps) {
+            peer = qemu_get_peer(ncs, i);
+        } else { /* Control Virtqueue */
+            peer = qemu_get_peer(ncs, n->max_queues);
+        }
 
-        peer = qemu_get_peer(ncs, i);
         net = get_vhost_net(peer);
         vhost_net_set_vq_index(net, i * 2);
 
@@ -340,14 +348,18 @@ int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
         }
      }
 
-    r = k->set_guest_notifiers(qbus->parent, total_queues * 2, true);
+    r = k->set_guest_notifiers(qbus->parent, total_notifiers, true);
     if (r < 0) {
         error_report("Error binding guest notifier: %d", -r);
         goto err;
     }
 
-    for (i = 0; i < total_queues; i++) {
-        peer = qemu_get_peer(ncs, i);
+    for (i = 0; i < nvhosts; i++) {
+        if (i < data_qps) {
+            peer = qemu_get_peer(ncs, i);
+        } else {
+            peer = qemu_get_peer(ncs, n->max_queues);
+        }
         r = vhost_net_start_one(get_vhost_net(peer), dev);
 
         if (r < 0) {
@@ -371,7 +383,7 @@ err_start:
         peer = qemu_get_peer(ncs , i);
         vhost_net_stop_one(get_vhost_net(peer), dev);
     }
-    e = k->set_guest_notifiers(qbus->parent, total_queues * 2, false);
+    e = k->set_guest_notifiers(qbus->parent, total_notifiers, false);
     if (e < 0) {
         fprintf(stderr, "vhost guest notifier cleanup failed: %d\n", e);
         fflush(stderr);
@@ -381,18 +393,27 @@ err:
 }
 
 void vhost_net_stop(VirtIODevice *dev, NetClientState *ncs,
-                    int total_queues)
+                    int data_qps, int cvq)
 {
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(dev)));
     VirtioBusState *vbus = VIRTIO_BUS(qbus);
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
+    VirtIONet *n = VIRTIO_NET(dev);
+    NetClientState *peer;
+    int total_notifiers = data_qps * 2 + cvq;
+    int nvhosts = data_qps + cvq;
     int i, r;
 
-    for (i = 0; i < total_queues; i++) {
-        vhost_net_stop_one(get_vhost_net(ncs[i].peer), dev);
+    for (i = 0; i < nvhosts; i++) {
+        if (i < data_qps) {
+            peer = qemu_get_peer(ncs, i);
+        } else {
+            peer = qemu_get_peer(ncs, n->max_queues);
+        }
+        vhost_net_stop_one(get_vhost_net(peer), dev);
     }
 
-    r = k->set_guest_notifiers(qbus->parent, total_queues * 2, false);
+    r = k->set_guest_notifiers(qbus->parent, total_notifiers, false);
     if (r < 0) {
         fprintf(stderr, "vhost guest notifier cleanup failed: %d\n", r);
         fflush(stderr);
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index bd7958b9f0..614660274c 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -285,14 +285,14 @@ static void virtio_net_vhost_status(VirtIONet *n, uint8_t status)
         }
 
         n->vhost_started = 1;
-        r = vhost_net_start(vdev, n->nic->ncs, queues);
+        r = vhost_net_start(vdev, n->nic->ncs, queues, 0);
         if (r < 0) {
             error_report("unable to start vhost net: %d: "
                          "falling back on userspace virtio", -r);
             n->vhost_started = 0;
         }
     } else {
-        vhost_net_stop(vdev, n->nic->ncs, queues);
+        vhost_net_stop(vdev, n->nic->ncs, queues, 0);
         n->vhost_started = 0;
     }
 }
diff --git a/include/net/vhost_net.h b/include/net/vhost_net.h
index fba40cf695..e656e38af9 100644
--- a/include/net/vhost_net.h
+++ b/include/net/vhost_net.h
@@ -21,8 +21,10 @@ typedef struct VhostNetOptions {
 uint64_t vhost_net_get_max_queues(VHostNetState *net);
 struct vhost_net *vhost_net_init(VhostNetOptions *options);
 
-int vhost_net_start(VirtIODevice *dev, NetClientState *ncs, int total_queues);
-void vhost_net_stop(VirtIODevice *dev, NetClientState *ncs, int total_queues);
+int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
+                    int data_qps, int cvq);
+void vhost_net_stop(VirtIODevice *dev, NetClientState *ncs,
+                    int data_qps, int cvq);
 
 void vhost_net_cleanup(VHostNetState *net);
 
-- 
2.25.1