[PATCH v7 net-next 5/9] virtio_net: add supports for extended offloads

[Paolo Abeni <pabeni@redhat.com>]

The virtio_net driver needs it to implement GSO over UDP tunnel
offload.

The only missing piece is mapping them to/from the extended
features.

Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
v4 -> v5:
 - avoid lines longer than 80 chars

v2 -> v3:
 - offload to feature conversion is now an inline function

v1 -> v2:
 - drop unused macro
 - restrict the offload remap range as per latest spec update
---
 drivers/net/virtio_net.c | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 9f6e0153ed2d..6f86a8edc981 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -35,6 +35,23 @@ module_param(csum, bool, 0444);
 module_param(gso, bool, 0444);
 module_param(napi_tx, bool, 0644);
 
+#define VIRTIO_OFFLOAD_MAP_MIN	46
+#define VIRTIO_OFFLOAD_MAP_MAX	47
+#define VIRTIO_FEATURES_MAP_MIN	65
+#define VIRTIO_O2F_DELTA	(VIRTIO_FEATURES_MAP_MIN - \
+				 VIRTIO_OFFLOAD_MAP_MIN)
+
+static bool virtio_is_mapped_offload(unsigned int obit)
+{
+	return obit >= VIRTIO_OFFLOAD_MAP_MIN &&
+	       obit <= VIRTIO_OFFLOAD_MAP_MAX;
+}
+
+static unsigned int virtio_offload_to_feature(unsigned int obit)
+{
+	return virtio_is_mapped_offload(obit) ? obit + VIRTIO_O2F_DELTA : obit;
+}
+
 /* FIXME: MTU in config. */
 #define GOOD_PACKET_LEN (ETH_HLEN + VLAN_HLEN + ETH_DATA_LEN)
 #define GOOD_COPY_LEN	128
@@ -7055,9 +7072,13 @@ static int virtnet_probe(struct virtio_device *vdev)
 		netif_carrier_on(dev);
 	}
 
-	for (i = 0; i < ARRAY_SIZE(guest_offloads); i++)
-		if (virtio_has_feature(vi->vdev, guest_offloads[i]))
+	for (i = 0; i < ARRAY_SIZE(guest_offloads); i++) {
+		unsigned int fbit;
+
+		fbit = virtio_offload_to_feature(guest_offloads[i]);
+		if (virtio_has_feature(vi->vdev, fbit))
 			set_bit(guest_offloads[i], &vi->guest_offloads);
+	}
 	vi->guest_offloads_capable = vi->guest_offloads;
 
 	rtnl_unlock();
-- 
2.49.0