Similar to IPIP and IP6I6 tunnels, introduce sw acceleration for IPv4 over
IPv6 and SIT tunnels in the netfilter flowtable infrastructure.

---
Changes in v4:
- Rebase on top of nf-next and fixed conflicts.
- Link to v3: https://lore.kernel.org/r/20260531-b4-flowtable-sw-accel-ip6ip-v3-0-56a2826f3279@kernel.org (local)

Changes in v3:
- Drop nf_flow_tunnel_v4_push and nf_flow_tunnel_v6_push routines
- Rebase on top of net-next tree.
- Link to v2: https://lore.kernel.org/r/20260506-b4-flowtable-sw-accel-ip6ip-v2-0-439fd427726e@kernel.org (local)

Changes in v2:
- Fix MTU check in nf_flow_offload_forward() and in
  nf_flow_offload_ipv6_forward()
- Add SIT sw acceleration support
- Link to v1: https://lore.kernel.org/r/20260505-b4-flowtable-sw-accel-ip6ip-v1-0-9ac39ccc9ea9@kernel.org (local)

---
Lorenzo Bianconi (6):
      net: netfilter: Add ether_type to net_device_path_ctx
      net: netfilter: Add encap_proto to flow_offload_tunnel
      net: netfilter: Add IPv4 over IPv6 tunnel flowtable acceleration
      selftests: netfilter: nft_flowtable.sh: Add IPv4 over IPv6 flowtable selftest
      net: netfilter: Add SIT tunnel flowtable acceleration
      selftests: netfilter: nft_flowtable.sh: Add SIT flowtable selftest

 drivers/net/ethernet/airoha/airoha_ppe.c           |  13 +-
 drivers/net/ethernet/mediatek/mtk_ppe_offload.c    |  13 +-
 include/linux/netdevice.h                          |   5 +-
 include/net/netfilter/nf_flow_table.h              |   1 +
 net/core/dev.c                                     |   6 +-
 net/ipv4/ipip.c                                    |   1 +
 net/ipv6/ip6_tunnel.c                              |   6 +-
 net/ipv6/sit.c                                     |  26 ++
 net/netfilter/nf_flow_table_core.c                 |  16 +-
 net/netfilter/nf_flow_table_ip.c                   | 397 +++++++++++++--------
 net/netfilter/nf_flow_table_path.c                 |  20 +-
 tools/testing/selftests/net/netfilter/config       |   1 +
 .../selftests/net/netfilter/nft_flowtable.sh       |  78 +++-
 13 files changed, 402 insertions(+), 181 deletions(-)
---
base-commit: 6fb33632323a396c9dc2bb9bea483e013e547d57
change-id: 20260505-b4-flowtable-sw-accel-ip6ip-7101034cd147

Best regards,
-- 
Lorenzo Bianconi [off-list ref]