[PATCH 2/2] virtio-net: ethtool configurable RXCSUM

[xiangxia . m . yue]

From: Tonghao Zhang <xiangxia.m....@gmail.com>

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.

Cc: Michael S. Tsirkin <m...@redhat.com>
Cc: Jason Wang <jasow...@redhat.com>
Signed-off-by: Tonghao Zhang <xiangxia.m....@gmail.com>
---
 drivers/net/virtio_net.c | 40 ++++++++++++++++++++++++++++------------
 1 file changed, 28 insertions(+), 12 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 21b71148c532..2e3af0b2c281 100644
--- 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;
@@ -2526,25 +2528,37 @@ 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 &
+                      vi->guest_offloads_capable;
        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;
                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;
+               else
+                       offloads &= ~GUEST_OFFLOAD_CSUM_MASK;
        }
 
+       if (offloads == (vi->guest_offloads &
+                        vi->guest_offloads_capable))
+               return 0;
+
+       err = virtnet_set_guest_offloads(vi, offloads);
+       if (err)
+               return err;
+
+       vi->guest_offloads = offloads;
        return 0;
 }
 
@@ -3013,8 +3027,10 @@ 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;
 
-- 
2.23.0