Merge branch 'devlink-net-mlx5-implement-swp_l4_csum_mode-via-devlink-params'

Daniel Zahka says:

====================
devlink: net/mlx5: implement swp_l4_csum_mode via devlink params

This series introduces a new devlink feature for querying param
default values, and resetting params to their default values. This
feature is then used to implement a new mlx5 driver param.

The series starts with two pure refactor patches: one that passes
through the extack to devlink_param::get() implementations. And a
second small refactor that prepares the netlink tlv handling code in
the devlink_param::get() path to better handle default parameter
values.

The third patch introduces the uapi and driver api for default
parameter values. The driver api is opt-in, and both the uapi and
driver api preserve existing behavior when not used by drivers or
userspace.

The fourth patch introduces a new mlx5 driver param, swp_l4_csum_mode,
for controlling tx csum behavior. The "l4_only" value of this param is
a dependency for PSP initialization on CX7 NICs.

Lastly, the series introduces a new driver param with cmode runtime to
netdevsim, and then uses this param in a new testcase for netdevsim
devlink params.

Here are some examples of using the default param uapi with the devlink
cli. Note the devlink cli binary I am using has changes which I am
posting in accompanying series targeting iproute2-next:

  # netdevsim
./devlink dev param show netdevsim/netdevsim0
netdevsim/netdevsim0:
  name max_macs type generic
    values:
      cmode driverinit value 32 default 32
  name test1 type driver-specific
    values:
      cmode driverinit value true default true

  # set to false
./devlink dev param set netdevsim/netdevsim0 name test1 value false cmode driverinit
./devlink dev param show netdevsim/netdevsim0
netdevsim/netdevsim0:
  name max_macs type generic
    values:
      cmode driverinit value 32 default 32
  name test1 type driver-specific
    values:
      cmode driverinit value false default true

  # set back to default
./devlink dev param set netdevsim/netdevsim0 name test1 default cmode driverinit
./devlink dev param show netdevsim/netdevsim0
netdevsim/netdevsim0:
  name max_macs type generic
    values:
      cmode driverinit value 32 default 32
  name test1 type driver-specific
    values:
      cmode driverinit value true default true

 # mlx5 params on cx7
./devlink dev param show pci/0000:01:00.0
pci/0000:01:00.0:
  name max_macs type generic
    values:
      cmode driverinit value 128 default 128
...
  name swp_l4_csum_mode type driver-specific
    values:
      cmode permanent value default default default

  # set to l4_only
./devlink dev param set pci/0000:01:00.0 name swp_l4_csum_mode value l4_only cmode permanent
./devlink dev param show pci/0000:01:00.0 name swp_l4_csum_mode
pci/0000:01:00.0:
  name swp_l4_csum_mode type driver-specific
    values:
      cmode permanent value l4_only default default

  # reset to default
./devlink dev param set pci/0000:01:00.0 name swp_l4_csum_mode default cmode permanent
./devlink dev param show pci/0000:01:00.0 name swp_l4_csum_mode
pci/0000:01:00.0:
  name swp_l4_csum_mode type driver-specific
    values:
      cmode permanent value default default default
====================

Link: https://patch.msgid.link/20251119025038.651131-1-daniel.zahka@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

3 files changed, 33 insertions, 0 deletions

diff --git a/Documentation/netlink/specs/devlink.yaml b/Documentation/netlink/specs/devlink.yaml
index 426d5aa7d955..837112da6738 100644
--- a/Documentation/netlink/specs/devlink.yaml
+++ b/Documentation/netlink/specs/devlink.yaml
@@ -859,6 +859,14 @@ attribute-sets:
         name: health-reporter-burst-period
         type: u64
         doc: Time (in msec) for recoveries before starting the grace period.
+
+      # TODO: fill in the attributes in between
+
+      -
+        name: param-reset-default
+        type: flag
+        doc: Request restoring parameter to its default value.
+        value: 183
   -
     name: dl-dev-stats
     subset-of: devlink
@@ -1793,6 +1801,7 @@ operations:
             - param-type
             # param-value-data is missing here as the type is variable
             - param-value-cmode
+            - param-reset-default
 
     -
       name: region-get
diff --git a/Documentation/networking/devlink/devlink-params.rst b/Documentation/networking/devlink/devlink-params.rst
index c0597d456641..ea17756dcda6 100644
--- a/Documentation/networking/devlink/devlink-params.rst
+++ b/Documentation/networking/devlink/devlink-params.rst
@@ -41,6 +41,16 @@ In order for ``driverinit`` parameters to take effect, the driver must
 support reloading via the ``devlink-reload`` command. This command will
 request a reload of the device driver.
 
+Default parameter values
+=========================
+
+Drivers may optionally export default values for parameters of cmode
+``runtime`` and ``permanent``. For ``driverinit`` parameters, the last
+value set by the driver will be used as the default value. Drivers can
+also support resetting params with cmode ``runtime`` and ``permanent``
+to their default values. Resetting ``driverinit`` params is supported
+by devlink core without additional driver support needed.
+
 .. _devlink_params_generic:
 
 Generic configuration parameters
diff --git a/Documentation/networking/devlink/mlx5.rst b/Documentation/networking/devlink/mlx5.rst
index 0e5f9c76e514..4bba4d780a4a 100644
--- a/Documentation/networking/devlink/mlx5.rst
+++ b/Documentation/networking/devlink/mlx5.rst
@@ -218,6 +218,20 @@ parameters.
        * ``balanced`` : Merges fewer CQEs, resulting in a moderate compression ratio but maintaining a balance between bandwidth savings and performance
        * ``aggressive`` : Merges more CQEs into a single entry, achieving a higher compression rate and maximizing performance, particularly under high traffic loads
 
+   * - ``swp_l4_csum_mode``
+     - string
+     - permanent
+     - Configure how the L4 checksum is calculated by the device when using
+       Software Parser (SWP) hints for header locations.
+
+       * ``default`` : Use the device's default checksum calculation
+         mode. The driver will discover during init whether or
+         full_csum or l4_only is in use. Setting this value explicitly
+         from userspace is not allowed, but some firmware versions may
+         return this value on param read.
+       * ``full_csum`` : Calculate full checksum including the pseudo-header
+       * ``l4_only`` : Calculate L4-only checksum, excluding the pseudo-header
+
 The ``mlx5`` driver supports reloading via ``DEVLINK_CMD_RELOAD``
 
 Info versions