Re: [PATCH v4 0/4] net/gve: add flow steering support

[Stephen Hemminger <stephen@networkplumber.org>]

On Wed,  4 Mar 2026 04:50:29 +0000
"Jasper Tran O'Leary" <jtranoleary@google.com> wrote:

> This patch series adds flow steering support to the Google Virtual
> Ethernet (gve) driver. This functionality allows traffic to be directed
> to specific receive queues based on user-specified flow patterns.
> 
> The series includes foundational support for extended admin queue
> commands needed to handle flow rules, the specific adminqueue commands
> for flow rule management, and the integration with the DPDK rte_flow
> API. The series adds support flow matching on the following protocols:
> IPv4, IPv6, TCP, UDP, SCTP, ESP, and AH.
> 
> Patch Overview:
> 
> 1. "net/gve: add flow steering device option" checks for and enables
>    the flow steering capability in the device options during
>    initialization.
> 2. "net/gve: introduce extended adminq command" adds infrastructure
>    for sending extended admin queue commands. These commands use a
>    flexible buffer descriptor format required for flow rule management.
> 3. "net/gve: add adminq commands for flow steering" implements the
>    specific admin queue commands to add and remove flow rules on the
>    device, including handling of rule IDs and parameters.
> 4. "net/gve: add rte flow API integration" exposes the flow steering
>    functionality via the DPDK rte_flow API. This includes strict
>    pattern validation, rule parsing, and lifecycle management (create,
>    destroy, flush). It ensures thread-safe access to the flow subsystem
>    and proper resource cleanup during device reset.
> 
> Jasper Tran O'Leary (2):
>   net/gve: add adminq commands for flow steering
>   net/gve: add rte flow API integration
> 
> Vee Agarwal (2):
>   net/gve: add flow steering device option
>   net/gve: introduce extended adminq command
> 
>  doc/guides/nics/features/gve.ini       |  12 +
>  doc/guides/nics/gve.rst                |  27 +
>  doc/guides/rel_notes/release_26_03.rst |   1 +
>  drivers/net/gve/base/gve.h             |   3 +-
>  drivers/net/gve/base/gve_adminq.c      | 118 ++++-
>  drivers/net/gve/base/gve_adminq.h      |  57 +++
>  drivers/net/gve/gve_ethdev.c           |  83 +++-
>  drivers/net/gve/gve_ethdev.h           |  46 ++
>  drivers/net/gve/gve_flow_rule.c        | 658 +++++++++++++++++++++++++
>  drivers/net/gve/gve_flow_rule.h        |  65 +++
>  drivers/net/gve/meson.build            |   1 +
>  11 files changed, 1066 insertions(+), 5 deletions(-)
>  create mode 100644 dpdk/drivers/net/gve/gve_flow_rule.c
>  create mode 100644 dpdk/drivers/net/gve/gve_flow_rule.h
> 


Applied to next-net

The detailed review report if you are interested.

Reviewed the v4 series. Overall this is well-structured — locking
discipline is sound, create/destroy/flush paths handle errors
correctly with proper resource cleanup, and the bitmap slot is
restored on adminq failure. Patches 1/4 and 2/4 are clean.

A few items on 3/4 and 4/4:

Patch 3/4:

  [Warning] struct gve_flow_spec has a padding hole after the
  tos/tclass u8 field (37 bytes of data, padded to 40 by the
  compiler). Callers zero-initialize today so no live bug, but
  consider adding GVE_CHECK_STRUCT_LEN for gve_flow_spec and
  gve_flow_rule_params to guard against future changes, consistent
  with other adminq structures.

Patch 4/4:

  [Warning] In gve_setup_flow_subsystem, the rte_zmalloc failure
  path does goto free_flow_rule_bmp which calls
  gve_flow_free_bmp(priv). This is safe (rte_free(NULL) is a
  no-op) but misleading — the label says "free" when there's
  nothing to free. Cleaner to just return -ENOMEM directly on the
  first failure.

  [Warning] gve_dev_reset tears down the flow subsystem and
  re-initializes via gve_init_priv, but does not destroy/recreate
  flow_rule_lock. This works today because
  gve_teardown_flow_subsystem doesn't destroy the mutex (only
  gve_dev_close does), but it's worth a comment to document this
  invariant.