linux-kernel - Re: [PATCH v4 0/3] introduce tee-based EFI Runtime Variable Service

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Message-ID: <CADQ0-X8njokPZQn+4oJn10yTHqDCByTLGDL7Yvdw+rKGWVzJwg@mail.gmail.com>
Date:   Fri, 26 May 2023 08:44:14 +0900
From:   Masahisa Kojima <masahisa.kojima@...aro.org>
To:     Ard Biesheuvel <ardb@...nel.org>
Cc:     Ilias Apalodimas <ilias.apalodimas@...aro.org>,
        Sumit Garg <sumit.garg@...aro.org>,
        Jens Wiklander <jens.wiklander@...aro.org>,
        linux-kernel@...r.kernel.org, op-tee@...ts.trustedfirmware.org,
        Johan Hovold <johan+linaro@...nel.org>
Subject: Re: [PATCH v4 0/3] introduce tee-based EFI Runtime Variable Service

Hi Ard,

On Fri, 26 May 2023 at 01:11, Ard Biesheuvel <ardb@...nel.org> wrote:
>
> On Wed, 24 May 2023 at 10:01, Ilias Apalodimas
> <ilias.apalodimas@...aro.org> wrote:
> >
> > Hi Sumit,
> >
> > On Wed, 24 May 2023 at 10:56, Sumit Garg <sumit.garg@...aro.org> wrote:
> > >
> > > On Tue, 23 May 2023 at 14:36, Masahisa Kojima
> > > <masahisa.kojima@...aro.org> wrote:
> > > >
> > > > This series introduces the tee based EFI Runtime Variable Service.
> > > >
> > > > The eMMC device is typically owned by the non-secure world(linux in
> > > > this case). There is an existing solution utilizing eMMC RPMB partition
> > > > for EFI Variables, it is implemented by interacting with
> > > > OP-TEE, StandaloneMM(as EFI Variable Service Pseudo TA), eMMC driver
> > > > and tee-supplicant. The last piece is the tee-based variable access
> > > > driver to interact with OP-TEE and StandaloneMM.
> > > >
> > > > Changelog:
> > > > v3 -> v4:
> > > > - replace the reference from EDK2 to PI Specification
> > > > - remove EDK2 source code reference comments
> > > > - prepare nonblocking variant of set_variable, it just returns
> > > >   EFI_UNSUPPORTED
> > > > - remove redundant buffer size check
> > > > - argument name change in mm_communicate
> > > > - function interface changes in setup_mm_hdr to remove (void **) cast
> > >
> > > I don't have detailed insights into how EFI spec mandates StandaloneMM
> > > should be implemented. But utilizing OP-TEE as the underlying
> > > transport here looks fine to me. FWIW,
> > >
> > > For the series:
> > > Acked-by: Sumit Garg <sumit.garg@...aro.org>
> >
> > Thanks!
> >
> >  FWIW the PI spec describes some of the functionality and how that
> > should be accessed.
> > There's a EFI_MM_COMMUNICATION_PROTOCOL which is not used here.
> > Instead the entry point is via an SMC to op-tee and the payload
> > adheres to what the PI spec describes in its EFI_MM_COMMUNICATE_HEADER
> >
>
> Thanks for the resend
>
> Could you please double check whether this needs any changes in
> relation to this patch?
>
> https://git.kernel.org/pub/scm/linux/kernel/git/efi/efi.git/commit/?id=d86ff3333cb1d5f4

I need to set a tee-based query_variable_info().
I will rebase to efi-next and send an updated version.

Thanks,
Masahisa Kojima