Re: [PATCH v16 09/10] arm_ffa: efi: introduce FF-A MM communication

Tom Rini
2023-07-26T19:39:22Z

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On Wed, Jul 26, 2023 at 10:45:02AM +0100, Abdellatif El Khlifi wrote:

> Add MM communication support using FF-A transport
>
> This feature allows accessing MM partitions services through
> EFI MM communication protocol. MM partitions such as StandAlonneMM
> or smm-gateway secure partitions which reside in secure world.
>
> An MM shared buffer and a door bell event are used to exchange
> the data.
>
> The data is used by EFI services such as GetVariable()/SetVariable()
> and copied from the communication buffer to the MM shared buffer.
>
> The secure partition is notified about availability of data in the
> MM shared buffer by an FF-A message (door bell).
>
> On such event, MM SP can read the data and updates the MM shared
> buffer with the response data.
>
> The response data is copied back to the communication buffer and
> consumed by the EFI subsystem.
>
> MM communication protocol supports FF-A 64-bit direct messaging.
>
> Signed-off-by: Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
> Tested-by: Gowtham Suresh Kumar <gowtham.sureshkumar@arm.com>
> Reviewed-by: Simon Glass <sjg@chromium.org>
> Cc: Tom Rini <trini@konsulko.com>
> Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
> Cc: Jens Wiklander <jens.wiklander@linaro.org>

So, at this point in the series we impact lx2160ardb_tfa_stmm which is
the only config in the tree prior to this series that sets
CONFIG_EFI_MM_COMM_TEE. I'm not going to block this series[1] on
updating lx2160ardb_tfa_stmm as well, but I do want to make sure the
maintainers there are aware and can update the config to support the
current state of this technology.

[1]: https://patchwork.ozlabs.org/project/uboot/list/?series=365876&state=*
--
Tom

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