virtio-net: ethtool configurable LRO

Virtio-net devices negotiate LRO support with the host.
Display the initially negotiated state with ethtool -k.

Also allow configuring it with ethtool -K, reusing the existing
virtnet_set_guest_offloads helper that configures LRO for XDP.
This is conditional on VIRTIO_NET_F_CTRL_GUEST_OFFLOADS.

Virtio-net negotiates TSO4 and TSO6 separately, but ethtool does not
distinguish between the two. Display LRO as on only if any offload
is active.

RTNL is held while calling virtnet_set_features, same as on the path
from virtnet_xdp_set.

Changes v1 -> v2
  - allow ethtool config (-K) only if VIRTIO_NET_F_CTRL_GUEST_OFFLOADS
  - show LRO as enabled if any LRO variant is enabled
  - do not allow configuration while XDP is active
  - differentiate current features from the capable set, to restore
    on XDP down only those features that were active on XDP up
  - move test out of VIRTIO_NET_F_CSUM/TSO branch, which is tx only

Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index ea672145f6a66b97ec3572f213939a64323fcdf3..0237250860467f296cb3ab8bb916b17f353bdf2f 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -236,6 +236,7 @@ struct virtnet_info {
        u32 speed;
 
        unsigned long guest_offloads;
+       unsigned long guest_offloads_capable;
 
        /* failover when STANDBY feature enabled */
        struct failover *failover;
@@ -2479,6 +2480,31 @@ static int virtnet_get_phys_port_name(struct net_device *dev, char *buf,
        return 0;
 }
 
+static int virtnet_set_features(struct net_device *dev,
+                               netdev_features_t features)
+{
+       struct virtnet_info *vi = netdev_priv(dev);
+       u64 offloads;
+       int err;
+
+       if ((dev->features ^ features) & NETIF_F_LRO) {
+               if (vi->xdp_queue_pairs)
+                       return -EBUSY;
+
+               if (features & NETIF_F_LRO)
+                       offloads = vi->guest_offloads_capable;
+               else
+                       offloads = 0;
+
+               err = virtnet_set_guest_offloads(vi, offloads);
+               if (err)
+                       return err;
+               vi->guest_offloads = offloads;
+       }
+
+       return 0;
+}
+
 static const struct net_device_ops virtnet_netdev = {
        .ndo_open            = virtnet_open,
        .ndo_stop            = virtnet_close,
@@ -2493,6 +2519,7 @@ static const struct net_device_ops virtnet_netdev = {
        .ndo_xdp_xmit           = virtnet_xdp_xmit,
        .ndo_features_check     = passthru_features_check,
        .ndo_get_phys_port_name = virtnet_get_phys_port_name,
+       .ndo_set_features       = virtnet_set_features,
 };
 
 static void virtnet_config_changed_work(struct work_struct *work)
@@ -2951,6 +2978,11 @@ static int virtnet_probe(struct virtio_device *vdev)
        }
        if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_CSUM))
                dev->features |= NETIF_F_RXCSUM;
+       if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
+           virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6))
+               dev->features |= NETIF_F_LRO;
+       if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS))
+               dev->hw_features |= NETIF_F_LRO;
 
        dev->vlan_features = dev->features;
 
@@ -3080,6 +3112,7 @@ static int virtnet_probe(struct virtio_device *vdev)
        for (i = 0; i < ARRAY_SIZE(guest_offloads); i++)
                if (virtio_has_feature(vi->vdev, guest_offloads[i]))
                        set_bit(guest_offloads[i], &vi->guest_offloads);
+       vi->guest_offloads_capable = vi->guest_offloads;
 
        pr_debug("virtnet: registered device %s with %d RX and TX vq's\n",
                 dev->name, max_queue_pairs);