[PATCH v5 3/3] vhost-user: Fix the virtio features negotiation flaw

[huangy81]

From: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>

This patch aims to fix unexpected negotiation features for
vhost-user netdev interface.

When openvswitch reconnect Qemu after an unexpected disconnection
and Qemu therefore start the vhost_dev, acked_features field in
vhost_dev is initialized with value fetched from acked_features
field in NetVhostUserState, which should be up-to-date at that
moment but Qemu could not make it actually during the time window
of virtio features negotiation.

So we save the acked_features right after being configured by
guest virtio driver so it can be used to restore acked_features
field in vhost_dev correctly.

Signed-off-by: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>
Signed-off-by: Guoyi Tu <tugy@chinatelecom.cn>
Signed-off-by: Liuxiangdong <liuxiangdong5@huawei.com>
---
 hw/net/vhost_net-stub.c | 5 +++++
 hw/net/vhost_net.c      | 7 +++++++
 hw/net/virtio-net.c     | 6 ++++++
 include/net/vhost_net.h | 1 +
 4 files changed, 19 insertions(+)

diff --git a/hw/net/vhost_net-stub.c b/hw/net/vhost_net-stub.c
index 89d71cf..199b099 100644
--- a/hw/net/vhost_net-stub.c
+++ b/hw/net/vhost_net-stub.c
@@ -101,3 +101,8 @@ int vhost_net_set_mtu(struct vhost_net *net, uint16_t mtu)
 {
     return 0;
 }
+
+void vhost_net_save_acked_features(NetClientState *nc)
+{
+
+}
diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index 30379d2..4c2698d 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -141,6 +141,13 @@ uint64_t vhost_net_get_acked_features(VHostNetState *net)
     return net->dev.acked_features;
 }
 
+void vhost_net_save_acked_features(NetClientState *nc)
+{
+    if (nc->info->type == NET_CLIENT_DRIVER_VHOST_USER) {
+        vhost_user_save_acked_features(nc);
+    }
+}
+
 static int vhost_net_get_fd(NetClientState *backend)
 {
     switch (backend->info->type) {
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 1067e72..5f22865 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -917,6 +917,12 @@ static void virtio_net_set_features(VirtIODevice *vdev, 
uint64_t features)
             continue;
         }
         vhost_net_ack_features(get_vhost_net(nc->peer), features);
+
+        /*
+         * keep acked_features in NetVhostUserState up-to-date so it
+         * can't miss any features configured by guest virtio driver.
+         */
+        vhost_net_save_acked_features(nc->peer);
     }
 
     if (virtio_has_feature(features, VIRTIO_NET_F_CTRL_VLAN)) {
diff --git a/include/net/vhost_net.h b/include/net/vhost_net.h
index 387e913..7bdbf48 100644
--- a/include/net/vhost_net.h
+++ b/include/net/vhost_net.h
@@ -48,4 +48,5 @@ uint64_t vhost_net_get_acked_features(VHostNetState *net);
 
 int vhost_net_set_mtu(struct vhost_net *net, uint16_t mtu);
 
+void vhost_net_save_acked_features(NetClientState *nc);
 #endif
-- 
1.8.3.1