linux-kernel - Re: [PATCH v2 1/3] tee: optee: Move pool

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Message-ID: <CAHUa44F=0juXyyhA7Bu0SzCK+1igRYEWCn1XRL1sDG1ZWNhr3g@mail.gmail.com>
Date: Wed, 28 Feb 2024 09:40:55 +0100
From: Jens Wiklander <jens.wiklander@...aro.org>
To: Sumit Garg <sumit.garg@...aro.org>
Cc: Balint Dobszay <balint.dobszay@....com>, op-tee@...ts.trustedfirmware.org, 
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, corbet@....net, sudeep.holla@....com, 
	rdunlap@...radead.org, krzk@...nel.org, gyorgy.szing@....com
Subject: Re: [PATCH v2 1/3] tee: optee: Move pool_op helper functions

On Wed, Feb 28, 2024 at 6:58 AM Sumit Garg <sumit.garg@...aro.org> wrote:
>
> On Tue, 27 Feb 2024 at 21:20, Jens Wiklander <jens.wiklander@...aro.org> wrote:
> >
> > On Tue, Feb 27, 2024 at 7:06 AM Sumit Garg <sumit.garg@...aro.org> wrote:
[snip]
> > > > --- a/include/linux/tee_drv.h
> > > > +++ b/include/linux/tee_drv.h
> > > > @@ -275,6 +275,17 @@ void *tee_get_drvdata(struct tee_device *teedev);
> > > >  struct tee_shm *tee_shm_alloc_priv_buf(struct tee_context *ctx, size_t size);
> > > >  struct tee_shm *tee_shm_alloc_kernel_buf(struct tee_context *ctx, size_t size);
> > > >
> > > > +int tee_shm_pool_op_alloc_helper(struct tee_shm_pool *pool, struct tee_shm *shm,
> > > > +                                size_t size, size_t align,
> > > > +                                int (*shm_register)(struct tee_context *ctx,
> > > > +                                                    struct tee_shm *shm,
> > > > +                                                    struct page **pages,
> > > > +                                                    size_t num_pages,
> > > > +                                                    unsigned long start));
> > > > +void tee_shm_pool_op_free_helper(struct tee_shm_pool *pool, struct tee_shm *shm,
> > > > +                                int (*shm_unregister)(struct tee_context *ctx,
> > > > +                                                      struct tee_shm *shm));
> > > > +
> > >
> > > These rather belong to drivers/tee/tee_private.h as we shouldn't
> > > expose them to other kernel client drivers.
> >
> > This is the right place, this .h file is for TEE drivers too.
> >
>
> But this is shared with other kernel TEE client drivers and we
> shouldn't expose internal APIs which aren't meant for them with a side
> effect of API abuse too. Any particular reason to not use
> drivers/tee/tee_private.h?

drivers/tee/tee_private.h is supposed to be used internally by only
the files in drivers/tee. If you look in include/linux/tee_drv.h
you'll find a few functions and other definitions that a kernel TEE
client driver should not use, for instance, tee_device_register() and
tee_device_unregister(). This kernel TEE client interface was
introduced with commit 25559c22cef8 ("tee: add kernel internal client
interface"). include/linux/tee_drv.h existed before we even had any
kernel TEE client interface.

Cheers,
Jens