[PATCH v3 4/4] virtio_net: Add support for VLAN filtering in the hypervisor

[Alex Williamson <alex.williamson@hp.com>]

VLAN filtering allows the hypervisor to drop packets from VLANs
that we're not a part of, further reducing the number of extraneous
packets recieved.  This makes use of the VLAN virtqueue command class.
The CTRL_VLAN feature bit tells us whether the backend supports VLAN
filtering.

Signed-off-by: Alex Williamson <alex.williamson@hp.com>
---

 drivers/net/virtio_net.c   |   31 ++++++++++++++++++++++++++++++-
 include/linux/virtio_net.h |   13 +++++++++++++
 2 files changed, 43 insertions(+), 1 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index e03eebf..d16107b 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -741,6 +741,30 @@ static void virtnet_set_rx_mode(struct net_device *dev)
 	kfree(buf);
 }
 
+static void virnet_vlan_rx_add_vid(struct net_device *dev, u16 vid)
+{
+	struct virtnet_info *vi = netdev_priv(dev);
+	struct scatterlist sg;
+
+	sg_set_buf(&sg, &vid, sizeof(vid));
+
+	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_VLAN,
+				  VIRTIO_NET_CTRL_VLAN_ADD, &sg, 1, 0))
+		dev_warn(&dev->dev, "Failed to add VLAN ID %d.\n", vid);
+}
+
+static void virnet_vlan_rx_kill_vid(struct net_device *dev, u16 vid)
+{
+	struct virtnet_info *vi = netdev_priv(dev);
+	struct scatterlist sg;
+
+	sg_set_buf(&sg, &vid, sizeof(vid));
+
+	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_VLAN,
+				  VIRTIO_NET_CTRL_VLAN_DEL, &sg, 1, 0))
+		dev_warn(&dev->dev, "Failed to kill VLAN ID %d.\n", vid);
+}
+
 static struct ethtool_ops virtnet_ethtool_ops = {
 	.set_tx_csum = virtnet_set_tx_csum,
 	.set_sg = ethtool_op_set_sg,
@@ -767,6 +791,8 @@ static const struct net_device_ops virtnet_netdev = {
 	.ndo_set_mac_address = virtnet_set_mac_address,
 	.ndo_set_rx_mode     = virtnet_set_rx_mode,
 	.ndo_change_mtu	     = virtnet_change_mtu,
+	.ndo_vlan_rx_add_vid = virnet_vlan_rx_add_vid,
+	.ndo_vlan_rx_kill_vid = virnet_vlan_rx_kill_vid,
 #ifdef CONFIG_NET_POLL_CONTROLLER
 	.ndo_poll_controller = virtnet_netpoll,
 #endif
@@ -894,6 +920,9 @@ static int virtnet_probe(struct virtio_device *vdev)
 			err = PTR_ERR(vi->svq);
 			goto free_send;
 		}
+
+		if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VLAN))
+			dev->features |= NETIF_F_HW_VLAN_FILTER;
 	}
 
 	/* Initialize our empty receive and send queues. */
@@ -984,7 +1013,7 @@ static unsigned int features[] = {
 	VIRTIO_NET_F_HOST_ECN, VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6,
 	VIRTIO_NET_F_GUEST_ECN, /* We don't yet handle UFO input. */
 	VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ,
-	VIRTIO_NET_F_CTRL_RX,
+	VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN,
 	VIRTIO_F_NOTIFY_ON_EMPTY,
 };
 
diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index 06d9dd6..f22bb39 100644
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -24,6 +24,7 @@
 #define VIRTIO_NET_F_STATUS	16	/* virtio_net_config.status available */
 #define VIRTIO_NET_F_CTRL_VQ	17	/* Control channel available */
 #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_S_LINK_UP	1	/* Link is up */
 
@@ -112,4 +113,16 @@ struct virtio_net_ctrl_mac {
 #define VIRTIO_NET_CTRL_MAC    1
  #define VIRTIO_NET_CTRL_MAC_TABLE_SET        0
 
+/*
+ * Control VLAN filtering
+ *
+ * The VLAN filter table is controlled via a simple ADD/DEL interface.
+ * VLAN IDs not added may be filterd by the hypervisor.  Del is the
+ * opposite of add.  Both commands expect an out entry containing a 2
+ * byte VLAN ID.
+ */
+#define VIRTIO_NET_CTRL_VLAN       2
+ #define VIRTIO_NET_CTRL_VLAN_ADD             0
+ #define VIRTIO_NET_CTRL_VLAN_DEL             1
+
 #endif /* _LINUX_VIRTIO_NET_H */