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net: airoha: add LRO offload support

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Introduce LRO offload support to the airoha_eth driver, leveraging
the EN7581/AN7583 SoC's 8 dedicated LRO hardware queues mapped to RX
queues 24-31. LRO offloading does not support Scatter-Gather (SG) so
it is required to increase the page_pool allocation order to 2 for RX
queues 24-31 (LRO queues).

Since LRO is configured per-QDMA and shared across all devices using
it, LRO is mutually exclusive with multiple devices bound to the
same QDMA block. NETIF_F_LRO availability is re-evaluated whenever the
QDMA user count changes (device registration and runtime QDMA
migration): airoha_update_netdev_features() drops the feature when the
QDMA has more than one user, while airoha_dev_set_qdma() re-enables LRO
on the destination QDMA after a migration so that a running device
keeps it active on the new QDMA block.

Set the GSO metadata (gso_type/gso_size/gso_segs) on aggregated packets,
together with CHECKSUM_PARTIAL and the pseudo-header checksum, so that
L3-forwarded traffic is correctly re-segmented by the GSO/TSO path on
the egress device.

The HW does not report the per-segment MSS (msg3[31:16] only reports
the max aggregated size), so the gso_size of an aggregated packet is
approximated as DIV_ROUND_UP(data_len, agg_count), i.e. the mean
segment size. Since this can never exceed the largest merged segment,
re-segmentation only produces smaller packets, which is safe.
Aggregated skbs are marked SKB_GSO_DODGY so that the stack recomputes
gso_segs from gso_size and does not merge the aggregate into the GRO
engine.

Performance comparison between sw GRO and LRO has been carried out using
a 10Gbps NIC:
GRO:    ~2.7 Gbps
LRO:    ~8.2 Gbps

Tested-by: Madhur Agrawal <madhur.agrawal@airoha.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260909-airoha-eth-lro-v7-1-e6317be79067@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Lorenzo Bianconi 2026-09-09 21:06:05 +02:00 • committed by Jakub Kicinski
commit a952507ca0
3 changed files with 390 additions and 22 deletions
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