[RFC v2 9/9] vhost: introduce vhost_set_vring_ready method

[Cindy Lu <lulu@redhat.com>]

From: Jason Wang <jasowang@redhat.com>

Vhost-vdpa introduces VHOST_VDPA_SET_VRING_ENABLE which complies the
semantic of queue_enable defined in virtio spec. This method can be
used for preventing device from executing request for a specific
virtqueue. This patch introduces the vhost_ops for this.

Note that, we've already had vhost_set_vring_enable which has different
semantic which allows to enable or disable a specific virtqueue for
some kinds of vhost backends. E.g vhost-user use this to changes the
number of active queue pairs.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 hw/net/vhost_net-stub.c |  4 ++++
 hw/net/vhost_net.c      | 11 ++++++++++-
 include/net/vhost_net.h |  1 +
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/hw/net/vhost_net-stub.c b/hw/net/vhost_net-stub.c
index aac0e98228..43e93e1a9a 100644
--- a/hw/net/vhost_net-stub.c
+++ b/hw/net/vhost_net-stub.c
@@ -86,6 +86,10 @@ int vhost_set_vring_enable(NetClientState *nc, int enable)
     return 0;
 }
 
+int vhost_set_vring_ready(NetClientState *nc)
+{
+    return 0;
+}
 int vhost_net_set_mtu(struct vhost_net *net, uint16_t mtu)
 {
     return 0;
diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index eff9ec9177..6911282a0a 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -375,7 +375,7 @@ int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
             goto err_start;
         }
 
-        if (ncs[i].peer->vring_enable) {
+        if (peer->vring_enable) {
             /* restore vring enable state */
             r = vhost_set_vring_enable(peer, peer->vring_enable);
 
@@ -496,6 +496,15 @@ int vhost_set_vring_enable(NetClientState *nc, int enable)
     return 0;
 }
 
+int vhost_set_vring_ready(NetClientState *nc)
+{
+    VHostNetState *net = get_vhost_net(nc);
+    const VhostOps *vhost_ops = net->dev.vhost_ops;
+    if (vhost_ops && vhost_ops->vhost_set_vring_ready) {
+        return vhost_ops->vhost_set_vring_ready(&net->dev);
+    }
+    return 0;
+}
 int vhost_net_set_mtu(struct vhost_net *net, uint16_t mtu)
 {
     const VhostOps *vhost_ops = net->dev.vhost_ops;
diff --git a/include/net/vhost_net.h b/include/net/vhost_net.h
index b47844bf29..247432a3b2 100644
--- a/include/net/vhost_net.h
+++ b/include/net/vhost_net.h
@@ -35,6 +35,7 @@ int vhost_net_notify_migration_done(VHostNetState *net, char* mac_addr);
 VHostNetState *get_vhost_net(NetClientState *nc);
 
 int vhost_set_vring_enable(NetClientState * nc, int enable);
+int vhost_set_vring_ready(NetClientState *nc);
 
 uint64_t vhost_net_get_acked_features(VHostNetState *net);
 
-- 
2.21.1