[RFC PATCH v7 11/25] virtio-net: Expose ctrl virtqueue logic

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

This allows external vhost-net devices to modify the state of the
VirtIO device model once vhost-vdpa device has acknowledge the control
commands.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 include/hw/virtio/virtio-net.h |  3 ++
 hw/net/virtio-net.c            | 83 ++++++++++++++++++++--------------
 2 files changed, 51 insertions(+), 35 deletions(-)

diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
index eb87032627..e62f9e227f 100644
--- a/include/hw/virtio/virtio-net.h
+++ b/include/hw/virtio/virtio-net.h
@@ -218,6 +218,9 @@ struct VirtIONet {
     struct EBPFRSSContext ebpf_rss;
 };
 
+unsigned virtio_net_handle_ctrl_iov(VirtIODevice *vdev,
+                                    const struct iovec *in_sg, size_t in_num,
+                                    struct iovec *out_sg, unsigned out_num);
 void virtio_net_set_netclient_name(VirtIONet *n, const char *name,
                                    const char *type);
 
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index e4748a7e6c..5905a9285c 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1419,57 +1419,70 @@ static int virtio_net_handle_mq(VirtIONet *n, uint8_t cmd,
     return VIRTIO_NET_OK;
 }
 
-static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
+unsigned virtio_net_handle_ctrl_iov(VirtIODevice *vdev,
+                                    const struct iovec *in_sg, size_t in_num,
+                                    struct iovec *out_sg, unsigned out_num)
 {
     VirtIONet *n = VIRTIO_NET(vdev);
     struct virtio_net_ctrl_hdr ctrl;
     virtio_net_ctrl_ack status = VIRTIO_NET_ERR;
-    VirtQueueElement *elem;
     size_t s;
     struct iovec *iov, *iov2;
-    unsigned int iov_cnt;
+
+    if (iov_size(in_sg, in_num) < sizeof(status) ||
+        iov_size(out_sg, out_num) < sizeof(ctrl)) {
+        virtio_error(vdev, "virtio-net ctrl missing headers");
+        return 0;
+    }
+
+    iov2 = iov = g_memdup2(out_sg, sizeof(struct iovec) * out_num);
+    s = iov_to_buf(iov, out_num, 0, &ctrl, sizeof(ctrl));
+    iov_discard_front(&iov, &out_num, sizeof(ctrl));
+    if (s != sizeof(ctrl)) {
+        status = VIRTIO_NET_ERR;
+    } else if (ctrl.class == VIRTIO_NET_CTRL_RX) {
+        status = virtio_net_handle_rx_mode(n, ctrl.cmd, iov, out_num);
+    } else if (ctrl.class == VIRTIO_NET_CTRL_MAC) {
+        status = virtio_net_handle_mac(n, ctrl.cmd, iov, out_num);
+    } else if (ctrl.class == VIRTIO_NET_CTRL_VLAN) {
+        status = virtio_net_handle_vlan_table(n, ctrl.cmd, iov, out_num);
+    } else if (ctrl.class == VIRTIO_NET_CTRL_ANNOUNCE) {
+        status = virtio_net_handle_announce(n, ctrl.cmd, iov, out_num);
+    } else if (ctrl.class == VIRTIO_NET_CTRL_MQ) {
+        status = virtio_net_handle_mq(n, ctrl.cmd, iov, out_num);
+    } else if (ctrl.class == VIRTIO_NET_CTRL_GUEST_OFFLOADS) {
+        status = virtio_net_handle_offloads(n, ctrl.cmd, iov, out_num);
+    }
+
+    s = iov_from_buf(in_sg, in_num, 0, &status, sizeof(status));
+    assert(s == sizeof(status));
+
+    g_free(iov2);
+    return sizeof(status);
+}
+
+static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
+{
+    VirtQueueElement *elem;
 
     for (;;) {
+        unsigned written;
         elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
         if (!elem) {
             break;
         }
-        if (iov_size(elem->in_sg, elem->in_num) < sizeof(status) ||
-            iov_size(elem->out_sg, elem->out_num) < sizeof(ctrl)) {
-            virtio_error(vdev, "virtio-net ctrl missing headers");
+
+        written = virtio_net_handle_ctrl_iov(vdev, elem->in_sg, elem->in_num,
+                                             elem->out_sg, elem->out_num);
+        if (written > 0) {
+            virtqueue_push(vq, elem, written);
+            virtio_notify(vdev, vq);
+            g_free(elem);
+        } else {
             virtqueue_detach_element(vq, elem, 0);
             g_free(elem);
             break;
         }
-
-        iov_cnt = elem->out_num;
-        iov2 = iov = g_memdup2(elem->out_sg,
-                               sizeof(struct iovec) * elem->out_num);
-        s = iov_to_buf(iov, iov_cnt, 0, &ctrl, sizeof(ctrl));
-        iov_discard_front(&iov, &iov_cnt, sizeof(ctrl));
-        if (s != sizeof(ctrl)) {
-            status = VIRTIO_NET_ERR;
-        } else if (ctrl.class == VIRTIO_NET_CTRL_RX) {
-            status = virtio_net_handle_rx_mode(n, ctrl.cmd, iov, iov_cnt);
-        } else if (ctrl.class == VIRTIO_NET_CTRL_MAC) {
-            status = virtio_net_handle_mac(n, ctrl.cmd, iov, iov_cnt);
-        } else if (ctrl.class == VIRTIO_NET_CTRL_VLAN) {
-            status = virtio_net_handle_vlan_table(n, ctrl.cmd, iov, iov_cnt);
-        } else if (ctrl.class == VIRTIO_NET_CTRL_ANNOUNCE) {
-            status = virtio_net_handle_announce(n, ctrl.cmd, iov, iov_cnt);
-        } else if (ctrl.class == VIRTIO_NET_CTRL_MQ) {
-            status = virtio_net_handle_mq(n, ctrl.cmd, iov, iov_cnt);
-        } else if (ctrl.class == VIRTIO_NET_CTRL_GUEST_OFFLOADS) {
-            status = virtio_net_handle_offloads(n, ctrl.cmd, iov, iov_cnt);
-        }
-
-        s = iov_from_buf(elem->in_sg, elem->in_num, 0, &status, sizeof(status));
-        assert(s == sizeof(status));
-
-        virtqueue_push(vq, elem, sizeof(status));
-        virtio_notify(vdev, vq);
-        g_free(iov2);
-        g_free(elem);
     }
 }
 
-- 
2.27.0