virtio-net: ethtool configurable RXCSUM

Allow user configuring RXCSUM separately with ethtool -K,
reusing the existing virtnet_set_guest_offloads helper
that configures RXCSUM for XDP. This is conditional on
VIRTIO_NET_F_CTRL_GUEST_OFFLOADS.

If Rx checksum is disabled, LRO should also be disabled.

Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20201012015820.62042-1-xiangxia.m.yue@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 21b7114..d2d2c4a 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -68,6 +68,8 @@ static const unsigned long guest_offloads[] = {
                                (1ULL << VIRTIO_NET_F_GUEST_ECN)  | \
                                (1ULL << VIRTIO_NET_F_GUEST_UFO))
 
+#define GUEST_OFFLOAD_CSUM_MASK (1ULL << VIRTIO_NET_F_GUEST_CSUM)
+
 struct virtnet_stat_desc {
        char desc[ETH_GSTRING_LEN];
        size_t offset;
@@ -2522,29 +2524,48 @@ static int virtnet_get_phys_port_name(struct net_device *dev, char *buf,
        return 0;
 }
 
+static netdev_features_t virtnet_fix_features(struct net_device *netdev,
+                                             netdev_features_t features)
+{
+       /* If Rx checksum is disabled, LRO should also be disabled. */
+       if (!(features & NETIF_F_RXCSUM))
+               features &= ~NETIF_F_LRO;
+
+       return features;
+}
+
 static int virtnet_set_features(struct net_device *dev,
                                netdev_features_t features)
 {
        struct virtnet_info *vi = netdev_priv(dev);
-       u64 offloads;
+       u64 offloads = vi->guest_offloads;
        int err;
 
-       if ((dev->features ^ features) & NETIF_F_LRO) {
-               if (vi->xdp_queue_pairs)
-                       return -EBUSY;
+       /* Don't allow configuration while XDP is active. */
+       if (vi->xdp_queue_pairs)
+               return -EBUSY;
 
+       if ((dev->features ^ features) & NETIF_F_LRO) {
                if (features & NETIF_F_LRO)
-                       offloads = vi->guest_offloads_capable;
+                       offloads |= GUEST_OFFLOAD_LRO_MASK &
+                                   vi->guest_offloads_capable;
                else
-                       offloads = vi->guest_offloads_capable &
-                                  ~GUEST_OFFLOAD_LRO_MASK;
+                       offloads &= ~GUEST_OFFLOAD_LRO_MASK;
+       }
 
-               err = virtnet_set_guest_offloads(vi, offloads);
-               if (err)
-                       return err;
-               vi->guest_offloads = offloads;
+       if ((dev->features ^ features) & NETIF_F_RXCSUM) {
+               if (features & NETIF_F_RXCSUM)
+                       offloads |= GUEST_OFFLOAD_CSUM_MASK &
+                                   vi->guest_offloads_capable;
+               else
+                       offloads &= ~GUEST_OFFLOAD_CSUM_MASK;
        }
 
+       err = virtnet_set_guest_offloads(vi, offloads);
+       if (err)
+               return err;
+
+       vi->guest_offloads = offloads;
        return 0;
 }
 
@@ -2563,6 +2584,7 @@ static const struct net_device_ops virtnet_netdev = {
        .ndo_features_check     = passthru_features_check,
        .ndo_get_phys_port_name = virtnet_get_phys_port_name,
        .ndo_set_features       = virtnet_set_features,
+       .ndo_fix_features       = virtnet_fix_features,
 };
 
 static void virtnet_config_changed_work(struct work_struct *work)
@@ -3013,8 +3035,10 @@ static int virtnet_probe(struct virtio_device *vdev)
        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))
+       if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS)) {
+               dev->hw_features |= NETIF_F_RXCSUM;
                dev->hw_features |= NETIF_F_LRO;
+       }
 
        dev->vlan_features = dev->features;