netdev - [RFC PATCH v2 4/8] virtio_net: add supports for extended offloads

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Message-ID: <bfac8c3cc2a36ca419ca583e3a43da0ed5185b8a.1748614223.git.pabeni@redhat.com>
Date: Fri, 30 May 2025 16:49:20 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: netdev@...r.kernel.org
Cc: Willem de Bruijn <willemdebruijn.kernel@...il.com>,
	Jason Wang <jasowang@...hat.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
	Eugenio Pérez <eperezma@...hat.com>,
	Yuri Benditovich <yuri.benditovich@...nix.com>,
	Akihiko Odaki <akihiko.odaki@...nix.com>
Subject: [RFC PATCH v2 4/8] virtio_net: add supports for extended offloads

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.

Signed-off-by: Paolo Abeni <pabeni@...hat.com>
---
v1 -> v2:
 - drop unused macro
 - restrict the offload remap range as per latest spec update
---
 drivers/net/virtio_net.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index e53ba600605a..ec638b4aa1c1 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -35,6 +35,24 @@ 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;
+}
+
+#define VIRTIO_OFFLOAD_TO_FEATURE(obit)	\
+	({								\
+		unsigned int __o = obit;				\
+		virtio_is_mapped_offload(__o) ? __o + VIRTIO_O2F_DELTA :\
+						__o;			\
+	})
+
 /* FIXME: MTU in config. */
 #define GOOD_PACKET_LEN (ETH_HLEN + VLAN_HLEN + ETH_DATA_LEN)
 #define GOOD_COPY_LEN	128
@@ -7037,9 +7055,13 @@ 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