[PATCH v1 0/2] net/dpaa2: fix RSS for plain and tunnelled traffic

[Maxime Leroy <maxime@leroys.fr>]

The RTE_ETH_RSS_LEVEL_INNERMOST support merged in 618a06c53d47 maps the
inner level to hdr_index = HDR_INDEX_LAST in the IP key extracts. The
hardware only resolves that index when several IP headers are stacked, so
a non-tunnelled frame, which carries a single IP header, resolves to
nothing: its RSS hash is constant and every such frame lands on a single
Rx queue. This breaks RSS for plain traffic, which the ethdev API
requires INNERMOST to hash, since a plain frame's innermost header is its
only IP header.

dpaa2 cannot express strict inner-only hashing and keep plain traffic
spread at the same time: the only index that resolves for a single header
is the outer one (index 0). This series therefore reverts the INNERMOST
support and, rather than exposing the RSS level selector, always extracts
both the outer IP (index 0) and the innermost IP (HDR_INDEX_LAST) as the
PMD default. Plain frames keep being hashed on their only IP header;
tunnelled frames are additionally spread on their inner IP.

The tradeoff, documented in the dpaa2 guide, is that two tunnelled flows
sharing an inner IP but differing in their outer IP may hash to different
queues. A future generic RSS level (for example OUTER_INNER) could expose
the distinction explicitly if other PMDs are interested.

Note on timing: the reverted INNERMOST support is present only in the
26.07 release candidates (currently rc4) and has never appeared in a DPDK
release. This series should be applied before 26.07 is released, so the
broken behaviour never ships and no cross-release regression is left
behind.

Maxime Leroy (2):
  net/dpaa2: revert inner RSS level support
  net/dpaa2: hash inner IP for tunnelled traffic

 doc/guides/nics/dpaa2.rst              |  3 +
 doc/guides/rel_notes/release_26_07.rst |  3 +-
 drivers/net/dpaa2/base/dpaa2_hw_dpni.c | 82 ++++++++++----------------
 drivers/net/dpaa2/dpaa2_ethdev.c       |  3 +-
 4 files changed, 36 insertions(+), 55 deletions(-)

-- 
2.43.0