From: Tonghao Zhang <redacted>

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 <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: Tonghao Zhang <redacted>
---
 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;
        }