mlxsw: Initialize register query payloads

MFGD register queries can exhaust EMAD retries and leave Mellanox
Spectrum switches stuck during boot or shutdown when running OpenWrt
built with GCC 15.

An example failure is shown below with the second line wrapped:

  EMAD retries (5/5) (tid=9b544fc100001f35)
  EMAD reg access failed (tid=9b544fc100001f35,reg_id=90f0(mfgd),
                          type=query,status=0(operation performed))

On an SN2100, the failure occurs during driver teardown on reboot.
On an SN3420, it occurs while probing mlxsw_spectrum during boot.

The register query API transmits the supplied payload to the device
before replacing it with the response. Both MFGD callers pass an
uninitialized stack buffer, so the request contains arbitrary register
field values and reserved bits. This makes the request depend on stack
contents and compiler code generation.

Initialize both MFGD query buffers in the firmware fatal event
configuration and reporter test paths. The initialization has been
confirmed to eliminate the boot and shutdown hangs on both switches.
The subsequent read-modify-write still preserves the other fields
returned by the device.

Also initialize the FORE fan fault query and the MOGCR mirroring policer
base query, which pass entirely uninitialized payloads. Restore the MTMP
query initialization in the temperature history reset path, where only
the slot and sensor index fields are set before querying the register.

This follows commit 5b0907407e7f ("mlxsw: core: Zero payload buffers for
couple of registers"), which initialized other query payloads after a
firmware field length bug caused firmware to consume uninitialized data.

Tested with firmware 2020.1148 and with 2016.3900 from linux-firmware.

Fixes: 7d83ee111008 ("mlxsw: core: Introduce fw_fatal health reporter")
Fixes: 2c6a33cd334b ("mlxsw: core: Extend hwmon interface with fan fault attribute")
Fixes: 4039504e6a0c ("mlxsw: spectrum_span: Allow setting policer on a SPAN agent")
Fixes: b890ad418e1f ("mlxsw: core_hwmon: Extend internal structures to support multi hwmon objects")
Cc: stable@vger.kernel.org
Signed-off-by: Til Kaiser <mail@tk154.de>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20261014173117.26305-1-mail@tk154.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions