vhost_net: do not assume nvqs is always 2

This patch switches to initialize dev.nvqs from the VhostNetOptions
instead of assuming it was 2. This is useful for implementing control
virtqueue support which will be a single vhost_net structure with a
single cvq.

Note that nvqs is still set to 2 for all users and this patch does not
change functionality.

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20210903091031.47303-6-jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/net/vhost_net.c

@@ -165,9 +165,9 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options)
         goto fail;
     }
     net->nc = options->net_backend;
+    net->dev.nvqs = options->nvqs;
 
     net->dev.max_queues = 1;
-    net->dev.nvqs = 2;
     net->dev.vqs = net->vqs;
 
     if (backend_kernel) {

include/net/vhost_net.h

@@ -14,6 +14,7 @@ typedef struct VhostNetOptions {
     VhostBackendType backend_type;
     NetClientState *net_backend;
     uint32_t busyloop_timeout;
+    unsigned int nvqs;
     void *opaque;
 } VhostNetOptions;
 

net/tap.c

@@ -749,6 +749,7 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
             qemu_set_nonblock(vhostfd);
         }
         options.opaque = (void *)(uintptr_t)vhostfd;
+        options.nvqs = 2;
 
         s->vhost_net = vhost_net_init(&options);
         if (!s->vhost_net) {

net/vhost-user.c

@@ -85,6 +85,7 @@ static int vhost_user_start(int queues, NetClientState *ncs[],
         options.net_backend = ncs[i];
         options.opaque      = be;
         options.busyloop_timeout = 0;
+        options.nvqs = 2;
         net = vhost_net_init(&options);
         if (!net) {
             error_report("failed to init vhost_net for queue %d", i);

net/vhost-vdpa.c

@@ -104,6 +104,7 @@ static int vhost_vdpa_add(NetClientState *ncs, void *be)
     options.net_backend = ncs;
     options.opaque      = be;
     options.busyloop_timeout = 0;
+    options.nvqs = 2;
 
     net = vhost_net_init(&options);
     if (!net) {