[RFC PATCH v8 03/21] vdpa: control virtqueue support on shadow virtqueue

[Eugenio Pérez]

Introduce the control virtqueue support for vDPA shadow virtqueue. This
is needed for advanced networking features like multiqueue.

To demonstrate command handling, VIRTIO_NET_F_CTRL_MACADDR and
VIRTIO_NET_CTRL_MQ are implemented. If vDPA device is started with SVQ
support and virtio-net driver changes MAC or the number of queues
virtio-net device model will be updated with the new one.

Others cvq commands could be added here straightforwardly but they have
been not tested.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 net/vhost-vdpa.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index df1e69ee72..ef12fc284c 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -11,6 +11,7 @@
 
 #include "qemu/osdep.h"
 #include "clients.h"
+#include "hw/virtio/virtio-net.h"
 #include "net/vhost_net.h"
 #include "net/vhost-vdpa.h"
 #include "hw/virtio/vhost-vdpa.h"
@@ -187,6 +188,46 @@ static NetClientInfo net_vhost_vdpa_info = {
         .check_peer_type = vhost_vdpa_check_peer_type,
 };
 
+static void vhost_vdpa_net_handle_ctrl(VirtIODevice *vdev,
+                                       const VirtQueueElement *elem)
+{
+    struct virtio_net_ctrl_hdr ctrl;
+    virtio_net_ctrl_ack status = VIRTIO_NET_ERR;
+    size_t s;
+    struct iovec in = {
+        .iov_base = &status,
+        .iov_len = sizeof(status),
+    };
+
+    s = iov_to_buf(elem->out_sg, elem->out_num, 0, &ctrl, sizeof(ctrl.class));
+    if (s != sizeof(ctrl.class)) {
+        return;
+    }
+
+    switch (ctrl.class) {
+    case VIRTIO_NET_CTRL_MAC_ADDR_SET:
+    case VIRTIO_NET_CTRL_MQ:
+        break;
+    default:
+        return;
+    };
+
+    s = iov_to_buf(elem->in_sg, elem->in_num, 0, &status, sizeof(status));
+    if (s != sizeof(status) || status != VIRTIO_NET_OK) {
+        return;
+    }
+
+    status = VIRTIO_NET_ERR;
+    virtio_net_handle_ctrl_iov(vdev, &in, 1, elem->out_sg, elem->out_num);
+    if (status != VIRTIO_NET_OK) {
+        error_report("Bad CVQ processing in model");
+    }
+}
+
+static const VhostShadowVirtqueueOps vhost_vdpa_net_svq_ops = {
+    .used_elem_handler = vhost_vdpa_net_handle_ctrl,
+};
+
 static NetClientState *net_vhost_vdpa_init(NetClientState *peer,
                                            const char *device,
                                            const char *name,
@@ -211,6 +252,9 @@ static NetClientState *net_vhost_vdpa_init(NetClientState 
*peer,
 
     s->vhost_vdpa.device_fd = vdpa_device_fd;
     s->vhost_vdpa.index = queue_pair_index;
+    if (!is_datapath) {
+        s->vhost_vdpa.shadow_vq_ops = &vhost_vdpa_net_svq_ops;
+    }
     ret = vhost_vdpa_add(nc, (void *)&s->vhost_vdpa, queue_pair_index, nvqs);
     if (ret) {
         qemu_del_net_client(nc);
-- 
2.27.0