linux-kernel - Re: [PATCHv8 1/3] optee: use uuid for sysfs driver entry

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Message-ID: <CAD8XO3axk-_BP1Nk_vT=u08OSuLmuEzXoSnmdB8pHKR_G2A1dw@mail.gmail.com>
Date:   Wed, 17 Jun 2020 17:12:56 +0300
From:   Maxim Uvarov <maxim.uvarov@...aro.org>
To:     Sumit Garg <sumit.garg@...aro.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "tee-dev @ lists . linaro . org" <tee-dev@...ts.linaro.org>,
        peterhuewe@....de,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jens Wiklander <jens.wiklander@...aro.org>,
        linux-integrity@...r.kernel.org, Arnd Bergmann <arnd@...aro.org>
Subject: Re: [PATCHv8 1/3] optee: use uuid for sysfs driver entry

On Wed, 17 Jun 2020 at 16:58, Sumit Garg <sumit.garg@...aro.org> wrote:
>
> Hi Maxim,
>
> On Thu, 4 Jun 2020 at 23:28, Maxim Uvarov <maxim.uvarov@...aro.org> wrote:
> >
> > With the evolving use-cases for TEE bus, now it's required to support
> > multi-stage enumeration process. But using a simple index doesn't
> > suffice this requirement and instead leads to duplicate sysfs entries.
> > So instead switch to use more informative device UUID for sysfs entry
> > like:
> > /sys/bus/tee/devices/optee-ta-<uuid>
> >
> > Signed-off-by: Maxim Uvarov <maxim.uvarov@...aro.org>
> > Reviewed-by: Sumit Garg <sumit.garg@...aro.org>
> > ---
> >  Documentation/ABI/testing/sysfs-bus-optee-devices | 8 ++++++++
> >  MAINTAINERS                                       | 1 +
> >  drivers/tee/optee/device.c                        | 9 ++++++---
> >  3 files changed, 15 insertions(+), 3 deletions(-)
> >  create mode 100644 Documentation/ABI/testing/sysfs-bus-optee-devices
> >
> > diff --git a/Documentation/ABI/testing/sysfs-bus-optee-devices b/Documentation/ABI/testing/sysfs-bus-optee-devices
> > new file mode 100644
> > index 000000000000..0ae04ae5374a
> > --- /dev/null
> > +++ b/Documentation/ABI/testing/sysfs-bus-optee-devices
> > @@ -0,0 +1,8 @@
> > +What:          /sys/bus/tee/devices/optee-ta-<uuid>/
> > +Date:           May 2020
> > +KernelVersion   5.7
> > +Contact:        tee-dev@...ts.linaro.org
> > +Description:
> > +               OP-TEE bus provides reference to registered drivers under this directory. The <uuid>
> > +               matches Trusted Application (TA) driver and corresponding TA in secure OS. Drivers
> > +               are free to create needed API under optee-ta-<uuid> directory.
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index ecc0749810b0..6717afef2de3 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -12516,6 +12516,7 @@ OP-TEE DRIVER
> >  M:     Jens Wiklander <jens.wiklander@...aro.org>
> >  L:     tee-dev@...ts.linaro.org
> >  S:     Maintained
> > +F:     Documentation/ABI/testing/sysfs-bus-optee-devices
> >  F:     drivers/tee/optee/
> >
> >  OP-TEE RANDOM NUMBER GENERATOR (RNG) DRIVER
> > diff --git a/drivers/tee/optee/device.c b/drivers/tee/optee/device.c
> > index e3a148521ec1..23d264c8146e 100644
> > --- a/drivers/tee/optee/device.c
> > +++ b/drivers/tee/optee/device.c
> > @@ -65,7 +65,7 @@ static int get_devices(struct tee_context *ctx, u32 session,
> >         return 0;
> >  }
> >
> > -static int optee_register_device(const uuid_t *device_uuid, u32 device_id)
> > +static int optee_register_device(const uuid_t *device_uuid)
> >  {
> >         struct tee_client_device *optee_device = NULL;
> >         int rc;
> > @@ -75,7 +75,10 @@ static int optee_register_device(const uuid_t *device_uuid, u32 device_id)
> >                 return -ENOMEM;
> >
> >         optee_device->dev.bus = &tee_bus_type;
> > -       dev_set_name(&optee_device->dev, "optee-clnt%u", device_id);
> > +       if (dev_set_name(&optee_device->dev, "optee-ta-%pUl", device_uuid)) {
>
> You should be using format specifier as: "%pUb" instead of "%pUl" as
> UUID representation for TAs is in big endian format. See below:
>
> # ls /sys/bus/tee/devices/
> optee-ta-405b6ad9-e5c3-e321-8794-1002a5d5c61b
> optee-ta-71d950bc-c9d4-c442-82cb-343fb7f37896
> optee-ta-e70f4af0-5d1f-9b4b-abf7-619b85b4ce8c
>
> While UUID for fTPM TA is in big endian format:
> bc50d971-d4c9-42c4-82cb-343fb7f37896
>
> Sorry that I missed it during review and noticed this while testing.
>
> With the above fix included, I tested this series using fTPM early TA
> on Qemu for aarch64 and used basic random number generation test using
> tpm2-tools. So feel free to add:
>
> Tested-by: Sumit Garg <sumit.garg@...aro.org>
>
> -Sumit
>
Oh, thanks. I will do v9 with this change and mailing list change.
Probalby you also need to check which prints are inside optee-os. I
think I copypasted this print from somewhere.

Maxim.

> > +               kfree(optee_device);
> > +               return -ENOMEM;
> > +       }
> >         uuid_copy(&optee_device->id.uuid, device_uuid);
> >
> >         rc = device_register(&optee_device->dev);
> > @@ -144,7 +147,7 @@ int optee_enumerate_devices(void)
> >         num_devices = shm_size / sizeof(uuid_t);
> >
> >         for (idx = 0; idx < num_devices; idx++) {
> > -               rc = optee_register_device(&device_uuid[idx], idx);
> > +               rc = optee_register_device(&device_uuid[idx]);
> >                 if (rc)
> >                         goto out_shm;
> >         }
> > --
> > 2.17.1
> >