Send virtio device id to the slave to indicate the device type.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
---
 hw/net/vhost_net.c        |  1 +
 hw/virtio/vhost-user.c    | 20 ++++++++++++++++++++
 include/hw/virtio/vhost.h |  1 +
 3 files changed, 22 insertions(+)

diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index 22874a9..ea9879f 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -155,6 +155,7 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options)
     net->dev.max_queues = 1;
     net->dev.nvqs = 2;
     net->dev.vqs = net->vqs;
+    net->dev.dev_type = VIRTIO_ID_NET;
 
     if (backend_kernel) {
         r = vhost_net_get_fd(options->net_backend);
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index d161884..1eba5e5 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -453,6 +453,18 @@ static int vhost_user_get_features(struct vhost_dev *dev, uint64_t *features)
     return vhost_user_get_u64(dev, VHOST_USER_GET_FEATURES, features);
 }
 
+static int vhost_user_set_dev_id(struct vhost_dev *dev, uint16_t virtio_id)
+{
+    VhostUserMsg msg = {
+        .request = VHOST_USER_SET_DEVICE_ID,
+        .flags = VHOST_USER_VERSION,
+        .payload.u64 = virtio_id,
+        .size = sizeof(msg.payload.u64),
+    };
+
+    return vhost_user_write(dev, &msg, NULL, 0);
+}
+
 static int vhost_user_set_owner(struct vhost_dev *dev)
 {
     VhostUserMsg msg = {
@@ -510,6 +522,14 @@ static int vhost_user_init(struct vhost_dev *dev, void *opaque)
             return err;
         }
 
+        if (dev->protocol_features &
+            (1ULL << VHOST_USER_PROTOCOL_F_SET_DEVICE_ID)) {
+            err = vhost_user_set_dev_id(dev, dev->dev_type);
+            if (err < 0) {
+                return err;
+            }
+        }
+
         /* query the max queues we support if backend supports Multiple Queue */
         if (dev->protocol_features & (1ULL << VHOST_USER_PROTOCOL_F_MQ)) {
             err = vhost_user_get_u64(dev, VHOST_USER_GET_QUEUE_NUM,
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index a450321..40ba87e 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -55,6 +55,7 @@ struct vhost_dev {
     int n_mem_sections;
     MemoryRegionSection *mem_sections;
     struct vhost_virtqueue *vqs;
+    uint16_t dev_type;
     int nvqs;
     /* the first virtqueue which would be used by this vhost dev */
     int vq_index;
-- 
2.7.4