linux-kernel - Re: [PATCH v3 1/2] tee: optee: Fix supplicant based device enumeration

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Message-ID: <61eb38c9-e40d-456a-86c8-e2d851b947f8@siemens.com>
Date:   Thu, 2 Nov 2023 09:05:27 +0100
From:   Jan Kiszka <jan.kiszka@...mens.com>
To:     Sumit Garg <sumit.garg@...aro.org>
Cc:     Jerome Forissier <jerome.forissier@...aro.org>,
        jens.wiklander@...aro.org, op-tee@...ts.trustedfirmware.org,
        arnd@...aro.org, ardb@...nel.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
Subject: Re: [PATCH v3 1/2] tee: optee: Fix supplicant based device
 enumeration

On 02.11.23 09:02, Sumit Garg wrote:
> On Thu, 2 Nov 2023 at 13:28, Jan Kiszka <jan.kiszka@...mens.com> wrote:
>>
>> On 02.11.23 08:37, Sumit Garg wrote:
>>> On Tue, 31 Oct 2023 at 17:14, Jan Kiszka <jan.kiszka@...mens.com> wrote:
>>>>
>>>> On 31.10.23 12:04, Jerome Forissier wrote:
>>>>>
>>>>>
>>>>> On 10/30/23 16:59, Sumit Garg wrote:
>>>>>> 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 separating supplicant dependent devices so that the
>>>>>> user-space service can detach supplicant devices before closing the
>>>>>> supplicant.
>>>>>>
>>>>>> Reported-by: Jan Kiszka <jan.kiszka@...mens.com>
>>>>>> Link: https://github.com/OP-TEE/optee_os/issues/6094
>>>>>> Fixes: 5f178bb71e3a ("optee: enable support for multi-stage bus enumeration")
>>>>>> Tested-by: Jan Kiszka <jan.kiszka@...mens.com>
>>>>>> Tested-by: Masahisa Kojima <masahisa.kojima@...aro.org>
>>>>>> Signed-off-by: Sumit Garg <sumit.garg@...aro.org>
>>>>>> ---
>>>>>>  drivers/tee/optee/device.c | 13 ++++++++++---
>>>>>>  1 file changed, 10 insertions(+), 3 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/tee/optee/device.c b/drivers/tee/optee/device.c
>>>>>> index 64f0e047c23d..78fc0a15c463 100644
>>>>>> --- a/drivers/tee/optee/device.c
>>>>>> +++ b/drivers/tee/optee/device.c
>>>>>> @@ -60,9 +60,10 @@ static void optee_release_device(struct device *dev)
>>>>>>      kfree(optee_device);
>>>>>>  }
>>>>>>
>>>>>> -static int optee_register_device(const uuid_t *device_uuid)
>>>>>> +static int optee_register_device(const uuid_t *device_uuid, u32 func)
>>>>>>  {
>>>>>>      struct tee_client_device *optee_device = NULL;
>>>>>> +    const char *dev_name_fmt = NULL;
>>>>>>      int rc;
>>>>>>
>>>>>>      optee_device = kzalloc(sizeof(*optee_device), GFP_KERNEL);
>>>>>> @@ -71,7 +72,13 @@ static int optee_register_device(const uuid_t *device_uuid)
>>>>>>
>>>>>>      optee_device->dev.bus = &tee_bus_type;
>>>>>>      optee_device->dev.release = optee_release_device;
>>>>>> -    if (dev_set_name(&optee_device->dev, "optee-ta-%pUb", device_uuid)) {
>>>>>> +
>>>>>> +    if (func == PTA_CMD_GET_DEVICES_SUPP)
>>>>>> +            dev_name_fmt = "optee-ta-supp-%pUb";
>>>>>> +    else
>>>>>> +            dev_name_fmt = "optee-ta-%pUb";
>>>>>
>>>>> That's an ABI change, isn't it?
>>>>
>>>
>>> Indeed it is an ABI break although we would like this to be backported
>>> but don't want to break existing users. So I brainstormed on it and
>>> came up with an alternative fix via device attribute in v4. Please
>>> have a look.
>>>
>>>> Oh, here did this come from! Yes, I recently had to adjust some systemd
>>>> service due to carrying this patch but looking for the change only in
>>>> upstream:
>>>>
>>>> https://github.com/ilbers/isar/commit/83644ddf694e51f11793e6107e4aaf68dc0043a5
>>>>
>>>
>>> You don't need to unbind all of the optee devices. v4 would help you
>>> to maintain backwards compatibility, can you retest it?
>>
>> How do I know from tee-supplicant perspective which devices I need to
>> unbind? There could be one in the future that will also use storage and
>> will therefore also fail once the supplicant is gone.
>>
> 
> With v4, the devices where the below attribute is present need to
> unbind before closing tee-supplicant.
> 
> /sys/bus/tee/devices/optee-ta-<uuid>/need_supplicant

OK - but that will only help in future kernels, nothing we have today.
Thus, the shutdown script cannot assume to alone kill those devices
unless it find a certain upcoming kernel release.

Jan

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