Add packet-mode ESP offload for Airoha/EIP93

This series adds the missing plumbing for ESP offload engines that
operate on whole ESP packets instead of only exposing AES/HMAC through
the crypto API AEAD interface.

The normal ESP software path can already call into accelerated AEAD
algorithms, but packet-mode engines such as EIP93 can also generate and
consume ESP packet framing: padding, pad length, next header and ICV.
That needs a slightly different XFRM offload contract so the netdev
driver can hand the skb to a packet backend rather than trying to make
hardware fit the software trailer layout.

Patch 1 extends the ESP offload infrastructure for packet engines while
preserving the existing behavior for drivers that do not opt in.
Patch 2 exposes an EIP93 ESP packet backend for encapsulation and
decapsulation.
Patch 3 wires Airoha Ethernet GDM netdevs and DSA user ports to that
backend through xfrmdev_ops. ESP GSO and ESP TX checksum offload remain
disabled.

Runtime testing was done on a Gemtek W1700K2 running OpenWrt with the
same changes applied on top of a 6.18.31-based kernel.

Test parameters:

  - Static IPv4 transport-mode XFRM SAs between the AP and host.
  - ESP transform: auth hmac(sha1), enc cbc(aes) with a 128-bit AES key.
  - iperf3 TCP test, AP as client and host as server:
        iperf3 -c <host_ip> -P 4 -t 10
  - The host always used normal Linux XFRM software processing.
  - With AP ESP offload disabled, the AP also used the Linux XFRM
    software path; in this setup, EIP93-backed AEAD crypto was still
    available to that path.

Network-relevant test setup:

  - AP: Gemtek W1700K2, Airoha AN7581/EN7581, 4x Arm Cortex-A53 at
    1.4 GHz, 2 GiB RAM, airoha_eth wan (GDM2) netdev, 10Gb/s full-duplex,
    MTU 9200, EIP93 crypto and IPsec packet engine present.
  - Host: AMD Ryzen 9 9950X3D, 16 cores/32 threads, Open vSwitch,
    MTU 9978, backed by a ConnectX-6 Dx 10Gb/s full-duplex link.

AP to host iperf3 result:

  AP offload      Sender          Receiver        Retransmits
  on              918.2 Mbit/s    913.6 Mbit/s    0
  off             782.4 Mbit/s    778.6 Mbit/s    3569

This is a 17.3% receiver-side throughput improvement for the AP TX ESP
path in this setup, with retransmits eliminated in the offloaded run.

Jihong Min (3):
  xfrm: extend ESP offload infrastructure for packet engines
  crypto: inside-secure: add EIP93 ESP packet backend
  net: airoha: add EIP93-backed ESP XFRM offload

 MAINTAINERS                                   |    1 +
 drivers/crypto/inside-secure/eip93/Kconfig    |   10 +
 drivers/crypto/inside-secure/eip93/Makefile   |    1 +
 .../crypto/inside-secure/eip93/eip93-ipsec.c  | 1413 ++++++++++++++++
 .../crypto/inside-secure/eip93/eip93-main.c   |   69 +-
 .../crypto/inside-secure/eip93/eip93-main.h   |   38 +-
 drivers/net/ethernet/airoha/Kconfig           |   11 +
 drivers/net/ethernet/airoha/Makefile          |    1 +
 drivers/net/ethernet/airoha/airoha_eth.c      |   51 +-
 drivers/net/ethernet/airoha/airoha_eth.h      |   69 +
 drivers/net/ethernet/airoha/airoha_xfrm.c     | 1474 +++++++++++++++++
 include/crypto/eip93-ipsec.h                  |  132 ++
 include/linux/netdevice.h                     |    3 +
 include/net/xfrm.h                            |    8 +-
 net/ipv4/esp4.c                               |    6 +-
 net/ipv4/esp4_offload.c                       |   29 +-
 net/ipv6/esp6.c                               |    6 +-
 net/ipv6/esp6_offload.c                       |   29 +-
 18 files changed, 3324 insertions(+), 27 deletions(-)
 create mode 100644 drivers/crypto/inside-secure/eip93/eip93-ipsec.c
 create mode 100644 drivers/net/ethernet/airoha/airoha_xfrm.c
 create mode 100644 include/crypto/eip93-ipsec.h

-- 
2.53.0