linux-kernel - [PATCH v4 0/2] tee: optee: Fixes for supplicant dependent enumeration

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Message-Id: <20231102073056.174480-1-sumit.garg@linaro.org>
Date:   Thu,  2 Nov 2023 13:00:54 +0530
From:   Sumit Garg <sumit.garg@...aro.org>
To:     jens.wiklander@...aro.org, op-tee@...ts.trustedfirmware.org
Cc:     jan.kiszka@...mens.com, arnd@...aro.org, ardb@...nel.org,
        jerome.forissier@...aro.org, ilias.apalodimas@...aro.org,
        masahisa.kojima@...aro.org, maxim.uvarov@...aro.org,
        jarkko.sakkinen@...ux.intel.com, linux-kernel@...r.kernel.org,
        diogo.ivo@...mens.com, Sumit Garg <sumit.garg@...aro.org>
Subject: [PATCH v4 0/2] tee: optee: Fixes for supplicant dependent enumeration

Currently supplicant dependent optee device enumeration only registers
devices whenever tee-supplicant is invoked for the first time. But it
forgets to remove devices when tee-supplicant daemon stops running and
closes its context gracefully. This leads to following error for fTPM
driver during reboot/shutdown:

[   73.466791] tpm tpm0: ftpm_tee_tpm_op_send: SUBMIT_COMMAND invoke error: 0xffff3024

Fix this by adding an attribute for supplicant dependent devices so that
the user-space service can detect and detach supplicant devices before
closing the supplicant:

$ for dev in /sys/bus/tee/devices/*; do if [[ -f "$dev/need_supplicant" && -f "$dev/driver/unbind" ]]; \
      then echo $(basename "$dev") > $dev/driver/unbind; fi done

While at it use the global system workqueue for OP-TEE bus scanning work
rather than our own custom one.

Changes in v4:
- Changing the device name would be an ABI break, rather switch to
  additional device attribute: "need_supplicant" to distinguish for ABI
  compatibility.
- Dropped tested-by for patch #1, I would encourage folks to retest
  this.

Changes in v3:

- Split patch into 2 separate ones, one for supplicant fix and other for
  the workqueue.

Changes in v2:

- Use device names to separate out tee-supplicant dependent devices via
  this patch.
- Since user-space service is aware about tee-supplicant lifespan, so
  allow the user-space service to unbind tee-supplicant dependent
  devices before killing the supplicant. Following command has to be
  added to the tee-supplicant service file.

  $ for dev in /sys/bus/tee/devices/*; do if [[ "$dev" == *"optee-ta-supp-"* ]]; \
        then echo $(basename "$dev") > $dev/driver/unbind; fi done

Sumit Garg (2):
  tee: optee: Fix supplicant based device enumeration
  tee: optee: Remove redundant custom workqueue

 .../ABI/testing/sysfs-bus-optee-devices         |  9 +++++++++
 drivers/tee/optee/core.c                        | 13 ++-----------
 drivers/tee/optee/device.c                      | 17 +++++++++++++++--
 drivers/tee/optee/optee_private.h               |  2 --
 4 files changed, 26 insertions(+), 15 deletions(-)

-- 
2.34.1