Re: [PATCH v2] efi_loader: Don't limit the StMM buffer size explicitly

[Ilias Apalodimas <ilias.apalodimas@linaro.org>]

On Sat, Dec 25, 2021 at 05:13:23PM +0100, Heinrich Schuchardt wrote:
> On 12/25/21 16:04, Ilias Apalodimas wrote:
> > 
> > 
> > On Sat, 25 Dec 2021, 16:28 Heinrich Schuchardt, <xypron.glpk@gmx.de
> > <mailto:xypron.glpk@gmx.de>> wrote:
> > 
> > 
> > 
> >     Am 25. Dezember 2021 12:16:29 MEZ schrieb Ilias Apalodimas
> >     <ilias.apalodimas@linaro.org <mailto:ilias.apalodimas@linaro.org>>:
> >      >> >
> >      >[...]
> >      >> >    rc = tee_invoke_func(conn.tee, &arg, 2, param);
> >      >> >    tee_shm_free(shm);
> >      >> > +  /*
> >      >> > +   * Although the max payload is configurable on StMM, we
> >     only share
> >      >> > +   * four pages from OP-TEE for the non-secure buffer used to
> >     communicate
> >      >> > +   * with StMM. OP-TEE will reject anything bigger than that
> >     and will
> >      >> > +   * return.  So le'ts at least warn users
> >      >> > +   */
> 
> The comment mentioning four pages does not make too much sense to me as
> both OP-TEE as well as U-Boot can be configured to other sizes.
> 

The pages that op-tee uses are not configurable.  What is configurable is
the number of pages you can request op-tee to map from the non-secure
world for u-boot sharing.  However the four page restriction I refer to 
is an internal op-tee one and refers to the non-secure world buffer it 
shares with StandAloneMM, not u-boot [1]

[...]

[1] https://github.com/OP-TEE/optee_os/blob/master/core/arch/arm/kernel/stmm_sp.c#L73
Cheers
/Ilias