[Qemu-devel] [PATCH 1/1] add loopback for virtio-net

[Hengjinxiao]

Sometimes it is necessary to test whether virtio-net can send and receive 
packets
normally, just as e1000 does. This patch adds loopback for virtio-net, when the
command 'VIRTIO_NET_CTRL_LOOPBACK_SET' is sent from front-end driver(such as 
virtio-net driver in linux.git), virtio-net goes into loopback mode, and the 
test 
above can be executed, then command 'VIRTIO_NET_CTRL_LOOPBACK_UNSET' can make 
virtio-net go back to previous state.

Signed-off-by: Hengjinxiao <address@hidden>

---
 hw/net/virtio-net.c            | 26 +++++++++++++++++++++++---
 include/hw/virtio/virtio-net.h |  9 +++++++++
 include/hw/virtio/virtio.h     |  1 +
 include/net/net.h              |  1 +
 net/net.c                      |  7 +++++--
 5 files changed, 39 insertions(+), 5 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 268eff9..ca313f4 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -778,6 +778,22 @@ static int virtio_net_handle_mq(VirtIONet *n, uint8_t cmd,
 
     return VIRTIO_NET_OK;
 }
+
+static int virtio_net_handle_loopback(VirtIONet *n, uint8_t cmd,
+                                      struct iovec *iov, unsigned int iov_cnt)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(n);
+    if (cmd == VIRTIO_NET_CTRL_LOOPBACK_SET) {
+        vdev->loopback = 1;
+        return VIRTIO_NET_OK;
+    } else if (cmd == VIRTIO_NET_CTRL_LOOPBACK_UNSET) {
+        vdev->loopback = 0;
+        return VIRTIO_NET_OK;
+    } else {
+        return VIRTIO_NET_ERR;
+    }
+}
+
 static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIONet *n = VIRTIO_NET(vdev);
@@ -813,6 +829,8 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, 
VirtQueue *vq)
             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);
+        } else if (ctrl.class == VIRTIO_NET_CTRL_LOOPBACK) {
+            status = virtio_net_handle_loopback(n, ctrl.cmd, iov, iov_cnt);
         }
 
         s = iov_from_buf(elem.in_sg, elem.in_num, 0, &status, sizeof(status));
@@ -1108,6 +1126,9 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q)
     VirtQueueElement elem;
     int32_t num_packets = 0;
     int queue_index = vq2q(virtio_get_queue_index(q->tx_vq));
+   NetClientState *sender = qemu_get_subqueue(n->nic, queue_index);
+
+   sender->loopback = vdev->loopback;
     if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
         return num_packets;
     }
@@ -1156,9 +1177,8 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q)
         }
 
         len = n->guest_hdr_len;
-
-        ret = qemu_sendv_packet_async(qemu_get_subqueue(n->nic, queue_index),
-                                      out_sg, out_num, virtio_net_tx_complete);
+
+       ret = qemu_sendv_packet_async(sender, out_sg, out_num,
+                                     virtio_net_tx_complete);
         if (ret == 0) {
             virtio_queue_set_notification(q->tx_vq, 0);
             q->async_tx.elem = elem;
diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
index 6ceb5aa..24e56bf 100644
--- a/include/hw/virtio/virtio-net.h
+++ b/include/hw/virtio/virtio-net.h
@@ -257,6 +257,15 @@ struct virtio_net_ctrl_mq {
 #define VIRTIO_NET_CTRL_GUEST_OFFLOADS   5
  #define VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET        0
 
+ /*
+  * Control Loopback
+  *
+  * The command VIRTIO_NET_CTRL_LOOPBACK_SET is used to require the device
+  * come into loopback state.
+  */
+#define VIRTIO_NET_CTRL_LOOPBACK   6
+ #define VIRTIO_NET_CTRL_LOOPBACK_SET        0
+ #define VIRTIO_NET_CTRL_LOOPBACK_UNSET        1
 #define DEFINE_VIRTIO_NET_FEATURES(_state, _field) \
         DEFINE_PROP_BIT("any_layout", _state, _field, VIRTIO_F_ANY_LAYOUT, 
true), \
         DEFINE_PROP_BIT("csum", _state, _field, VIRTIO_NET_F_CSUM, true), \
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index a60104c..219e0d2 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -128,6 +128,7 @@ struct VirtIODevice
     VMChangeStateEntry *vmstate;
     char *bus_name;
     uint8_t device_endian;
+   uint8_t loopback;
 };
 
 typedef struct VirtioDeviceClass {
diff --git a/include/net/net.h b/include/net/net.h
index ed594f9..ce66b86 100644
--- a/include/net/net.h
+++ b/include/net/net.h
@@ -89,6 +89,7 @@ struct NetClientState {
     NetClientDestructor *destructor;
     unsigned int queue_index;
     unsigned rxfilter_notify_enabled:1;
+   int loopback;
 };
 
 typedef struct NICState {
diff --git a/net/net.c b/net/net.c
index 6d930ea..f4c1ef4 100644
--- a/net/net.c
+++ b/net/net.c
@@ -611,8 +611,11 @@ ssize_t qemu_sendv_packet_async(NetClientState *sender,
     if (sender->link_down || !sender->peer) {
         return iov_size(iov, iovcnt);
     }
-
-    queue = sender->peer->incoming_queue;
+    if (sender->loopback) {
+        queue = sender->incoming_queue;
+    } else {
+        queue = sender->peer->incoming_queue;
+    }
 
     return qemu_net_queue_send_iov(queue, sender,
                                    QEMU_NET_PACKET_FLAG_NONE,
-- 
1.8.3.2