[Qemu-devel] [PATCH V7 4/5] virtio-net: notify guest to annouce itself

[Jason Wang <jasowang@redhat.com>]

It's hard to track all mac addresses and their configurations (e.g vlan) in
qemu. Without those information, it's impossible to build proper garp packet
after migration. The only possible solution to this is let guest ( who knew all
configurations) to do this.

So, this patch introduces a new rw config status bit of virtio-net,
VIRTIO_NET_S_ANNOUNCE which is used to notify guest to announce presence of its
link through config update interrupt. When gust have done the announcement, it
should ack the notification through VIRTIO_NET_CTRL_ANNOUNCE_ACK cmd. This
feature is negotiated by a new feature bit VIRTIO_NET_F_ANNOUNCE.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 hw/virtio-net.c |   30 ++++++++++++++++++++++++++++++
 hw/virtio-net.h |   15 ++++++++++++++-
 2 files changed, 44 insertions(+), 1 deletions(-)

diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index 009f09e..278c42c 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -610,6 +610,18 @@ static int virtio_net_handle_mq(VirtIONet *n, uint8_t cmd,
 
     return VIRTIO_NET_OK;
 }
+
+static int virtio_net_handle_announce(VirtIONet *n, uint8_t cmd,
+                                      struct iovec *iov, unsigned int iov_cnt)
+{
+    if (cmd == VIRTIO_NET_CTRL_ANNOUNCE_ACK) {
+        n->status &= ~VIRTIO_NET_S_ANNOUNCE;
+        return VIRTIO_NET_OK;
+    } else {
+        return VIRTIO_NET_ERR;
+    }
+}
+
 static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIONet *n = to_virtio_net(vdev);
@@ -639,6 +651,8 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
             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);
         }
@@ -1275,6 +1289,21 @@ static void virtio_net_cleanup(NetClientState *nc)
     n->nic = NULL;
 }
 
+static int virtio_net_announce(NetClientState *nc)
+{
+    VirtIONet *n = qemu_get_nic_opaque(nc);
+
+    if (n->vdev.guest_features & (0x1 << VIRTIO_NET_F_GUEST_ANNOUNCE)
+        && n->vdev.guest_features & (0x1 << VIRTIO_NET_F_CTRL_VQ)
+        && virtio_net_started(n, n->vdev.status)) {
+        n->status |= VIRTIO_NET_S_ANNOUNCE;
+        virtio_notify_config(&n->vdev);
+        return 0;
+    }
+
+    return -1;
+}
+
 static NetClientInfo net_virtio_info = {
     .type = NET_CLIENT_OPTIONS_KIND_NIC,
     .size = sizeof(NICState),
@@ -1282,6 +1311,7 @@ static NetClientInfo net_virtio_info = {
     .receive = virtio_net_receive,
         .cleanup = virtio_net_cleanup,
     .link_status_changed = virtio_net_set_link_status,
+    .announce = virtio_net_announce,
 };
 
 static bool virtio_net_guest_notifier_pending(VirtIODevice *vdev, int idx)
diff --git a/hw/virtio-net.h b/hw/virtio-net.h
index e654c13..c0f3de5 100644
--- a/hw/virtio-net.h
+++ b/hw/virtio-net.h
@@ -43,12 +43,13 @@
 #define VIRTIO_NET_F_CTRL_RX    18      /* Control channel RX mode support */
 #define VIRTIO_NET_F_CTRL_VLAN  19      /* Control channel VLAN filtering */
 #define VIRTIO_NET_F_CTRL_RX_EXTRA 20   /* Extra RX mode control support */
+#define VIRTIO_NET_F_GUEST_ANNOUNCE 21  /* Guest can announce itself */
 #define VIRTIO_NET_F_MQ         22      /* Device supports Receive Flow
                                          * Steering */
-
 #define VIRTIO_NET_F_CTRL_MAC_ADDR   23 /* Set MAC address */
 
 #define VIRTIO_NET_S_LINK_UP    1       /* Link is up */
+#define VIRTIO_NET_S_ANNOUNCE   2       /* Announcement is needed */
 
 #define TX_TIMER_INTERVAL 150000 /* 150 us */
 
@@ -152,6 +153,17 @@ struct virtio_net_ctrl_mac {
  #define VIRTIO_NET_CTRL_VLAN_DEL             1
 
 /*
+ * Control link announce acknowledgement
+ *
+ * The command VIRTIO_NET_CTRL_ANNOUNCE_ACK is used to indicate that
+ * driver has recevied the notification and device would clear the
+ * VIRTIO_NET_S_ANNOUNCE bit in the status filed after it received
+ * this command.
+ */
+#define VIRTIO_NET_CTRL_ANNOUNCE       3
+ #define VIRTIO_NET_CTRL_ANNOUNCE_ACK         0
+
+/*
  * Control Multiqueue
  *
  * The command VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET
@@ -180,6 +192,7 @@ struct virtio_net_ctrl_mq {
         DEFINE_PROP_BIT("guest_tso6", _state, _field, VIRTIO_NET_F_GUEST_TSO6, true), \
         DEFINE_PROP_BIT("guest_ecn", _state, _field, VIRTIO_NET_F_GUEST_ECN, true), \
         DEFINE_PROP_BIT("guest_ufo", _state, _field, VIRTIO_NET_F_GUEST_UFO, true), \
+        DEFINE_PROP_BIT("guest_announce", _state, _field, VIRTIO_NET_F_GUEST_ANNOUNCE, true), \
         DEFINE_PROP_BIT("host_tso4", _state, _field, VIRTIO_NET_F_HOST_TSO4, true), \
         DEFINE_PROP_BIT("host_tso6", _state, _field, VIRTIO_NET_F_HOST_TSO6, true), \
         DEFINE_PROP_BIT("host_ecn", _state, _field, VIRTIO_NET_F_HOST_ECN, true), \
-- 
1.7.1