[RFC PATCH v4 17/20] vdpa: Add vhost_vdpa_start_control_svq

["Eugenio Pérez" <eperezma@redhat.com>]

This will send CVQ commands in the destination machine, seting up
everything o there is no guest-visible change.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 net/vhost-vdpa.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index 585d2f60f8..6dc0ae8614 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -205,10 +205,73 @@ static ssize_t vhost_vdpa_receive(NetClientState *nc, const uint8_t *buf,
     return 0;
 }
 
+static bool vhost_vdpa_start_control_svq(VhostShadowVirtqueue *svq,
+                                         VirtIODevice *vdev)
+{
+    VirtIONet *n = VIRTIO_NET(vdev);
+    uint64_t features = vdev->host_features;
+
+    if (features & BIT_ULL(VIRTIO_NET_F_CTRL_MAC_ADDR)) {
+        const struct virtio_net_ctrl_hdr ctrl = {
+            .class = VIRTIO_NET_CTRL_MAC,
+            .cmd = VIRTIO_NET_CTRL_MAC_ADDR_SET,
+        };
+        uint8_t mac[6];
+        const struct iovec data[] = {
+            {
+                .iov_base = (void *)&ctrl,
+                .iov_len = sizeof(ctrl),
+            },{
+                .iov_base = mac,
+                .iov_len = sizeof(mac),
+            },{
+                .iov_base = NULL,
+                .iov_len = sizeof(virtio_net_ctrl_ack),
+            }
+        };
+        bool ret;
+
+        /* TODO: Only best effort? */
+        memcpy(mac, n->mac, sizeof(mac));
+        ret = vhost_svq_inject(svq, data, 2, 1);
+        if (!ret) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+static void vhost_vdpa_start(NetClientState *nc)
+{
+    assert(nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA);
+    VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
+    struct vhost_vdpa *v = &s->vhost_vdpa;
+    struct vhost_dev *dev = &s->vhost_net->dev;
+    VhostShadowVirtqueue *svq;
+
+    if (nc->is_datapath) {
+        /* This is not the cvq dev */
+        return;
+    }
+
+    if (dev->vq_index + dev->nvqs != dev->vq_index_end) {
+        return;
+    }
+
+    if (!v->shadow_vqs_enabled) {
+        return;
+    }
+
+    svq = g_ptr_array_index(v->shadow_vqs, 0);
+    vhost_vdpa_start_control_svq(svq, dev->vdev);
+}
+
 static NetClientInfo net_vhost_vdpa_info = {
         .type = NET_CLIENT_DRIVER_VHOST_VDPA,
         .size = sizeof(VhostVDPAState),
         .receive = vhost_vdpa_receive,
+        .start = vhost_vdpa_start,
         .cleanup = vhost_vdpa_cleanup,
         .has_vnet_hdr = vhost_vdpa_has_vnet_hdr,
         .has_ufo = vhost_vdpa_has_ufo,
-- 
2.27.0