[PATCH v4 0/3] net/gve: TSO descriptor count fixes for GVE DQO

[Joshua Washington <joshwash@google.com>]

https://inbox.dpdk.org/dev/20250707231812.1937260-7-joshwash@google.com/
introduced descriptor limit checks for TSO packets in DPDK.
Unfortunately, a couple of bugs have been found in the implementation.

This patch series introduces fixes for those bugs and adds support for
the tx_pkt_prepare callback to reject potentially invalid packets before
they are dropped in the transmission path. Before a recently introduced
patch, the GVE behavior was to stop transmitting at the first invalid
packet, which would allow the application to do any necessary
linearization or packet modification before attempting to transmit
again. It turns out that that behavior is considered incorrect, so offer
tx_pkt_prepare as an alternative.

Changes in v4:
- Remove unnecessary checksum check when TSO is enabled.

Changes in v3:
- Remove extraneous Fixes tags.
- Drop patch 2 allowing multi-segment HEADERS, since that conflicts with
  tx_pkt_prepare.

Changes in v2:
- Rely on tx_pkt->nb_segs for descriptor limit calculation only as a
  precursor, falling back to the traditional gve_tx_pkt_nb_data_descs()
  if that optimization fails.
- Only call rte_net_intel_cksum_preapre on TSO packets that request
  checksum offloading. This enforces the additional requirement that
  headers are all in the same mbuf segment.
- Introduce new patch to validate minimum header length

Joshua Washington (3):
  net/gve: fix TSO segment offset calculation
  net/gve: introduce Tx packet preparation for DQO format
  net/gve: validate minimum header length for TSO packets

 drivers/net/gve/base/gve_desc_dqo.h |  1 +
 drivers/net/gve/gve_ethdev.h        |  3 ++
 drivers/net/gve/gve_tx_dqo.c        | 84 +++++++++++++++++++++++++++--
 3 files changed, 83 insertions(+), 5 deletions(-)

-- 
2.56.0.542.g3ef89b7020-goog