net/mlx5e: Do not increment ESN when updating IPsec ESN state

net/mlx5e: Do not increment ESN when updating IPsec ESN state

An offloaded SA stops receiving after about 2^32 + replay_window
packets. For example, when SA reaches <seq-hi 0x1, seq 0x2c>, all
subsequent packets get dropped with SA-icv-failure (integrity_failed).

To reproduce the bug:
- ConnectX-6 Dx with crypto enabled (FW 22.30.1004)
- ipsec.conf:
  nic-offload = yes
  replay-window = 32
  esn = yes
  salifetime=24h
- Run netperf for a long time to send more than 2^32 packets
  netperf -H <device-under-test> -t TCP_STREAM -l 20000

When 2^32 + replay_window packets are received, the replay window
moves from the 2nd half of subspace (overlap=1) to the 1st half
(overlap=0). The driver then updates the 'esn' value in NIC
(i.e. seq_hi) as follows.

 seq_hi = xfrm_replay_seqhi(seq_bottom)
 new esn in NIC = seq_hi + 1

The +1 increment is wrong, as seq_hi already contains the correct
seq_hi. For example, when seq_hi=1, the driver actually tells NIC to
use seq_hi=2 (esn). This incorrect esn value causes all subsequent
packets to fail integrity checks (SA-icv-failure). So, do not
increment.

Fixes: cb01008390bb ("net/mlx5: IPSec, Add support for ESN")
Signed-off-by: Hyong Youb Kim <hyonkim@cisco.com>
Acked-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Link: https://lore.kernel.org/r/20221026135153.154807-2-saeed@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>