linux-kernel - Re: [PATCH 00/11] arm64: qcom: add and enable SHM Bridge support

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Message-ID: <CAA8EJpp_Uu62TDknZ-X0DQYinnwxxoriPpetfppCySxg_25YQg@mail.gmail.com>
Date:   Tue, 29 Aug 2023 00:23:59 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Arnd Bergmann <arnd@...db.de>,
        Alex Elder <elder@...aro.org>,
        Srini Kandagatla <srinivas.kandagatla@...aro.org>,
        kernel@...cinc.com, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 00/11] arm64: qcom: add and enable SHM Bridge support

On Mon, 28 Aug 2023 at 22:29, Bartosz Golaszewski
<bartosz.golaszewski@...aro.org> wrote:
>
> SHM Bridge is a mechanism allowing to map limited areas of kernel's
> virtual memory to physical addresses and share those with the
> trustzone in order to not expose the entire RAM for SMC calls.
>
> This series adds support for Qualcomm SHM Bridge in form of a platform
> driver and library functions available to users. It enables SHM Bridge
> support for three platforms and contains a bunch of cleanups for
> qcom-scm.

Which users do you expect for this API?

Also, could you please describe your design a bit more? Why have you
implemented the shm-bridge as a separate driver rather than a part of
the SCM driver?

>
> Bartosz Golaszewski (11):
>   firmware: qcom-scm: drop unneeded 'extern' specifiers
>   firmware: qcom-scm: order includes alphabetically
>   firmware: qcom-scm: atomically assign and read the global __scm
>     pointer
>   firmware: qcom-scm: add support for SHM bridge operations
>   dt-bindings: document the Qualcomm TEE Shared Memory Bridge
>   firmware: qcom-shm-bridge: new driver
>   firmware: qcom-scm: use SHM bridge if available
>   arm64: defconfig: enable Qualcomm SHM bridge module
>   arm64: dts: qcom: sm8450: enable SHM bridge
>   arm64: dts: qcom: sa8775p: enable SHM bridge
>   arm64: dts: qcom: sm8150: enable SHM bridge
>
>  .../bindings/firmware/qcom,shm-bridge.yaml    |  36 ++
>  arch/arm64/boot/dts/qcom/sa8775p.dtsi         |   4 +
>  arch/arm64/boot/dts/qcom/sm8150.dtsi          |   4 +
>  arch/arm64/boot/dts/qcom/sm8450.dtsi          |   4 +
>  arch/arm64/configs/defconfig                  |   1 +
>  drivers/firmware/Kconfig                      |   8 +
>  drivers/firmware/Makefile                     |   1 +
>  drivers/firmware/qcom-shm-bridge.c            | 452 ++++++++++++++++++
>  drivers/firmware/qcom_scm-smc.c               |  20 +-
>  drivers/firmware/qcom_scm.c                   | 106 +++-
>  drivers/firmware/qcom_scm.h                   |   3 +
>  include/linux/firmware/qcom/qcom_scm.h        | 109 +++--
>  include/linux/firmware/qcom/shm-bridge.h      |  32 ++
>  13 files changed, 712 insertions(+), 68 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/firmware/qcom,shm-bridge.yaml
>  create mode 100644 drivers/firmware/qcom-shm-bridge.c
>  create mode 100644 include/linux/firmware/qcom/shm-bridge.h
>
> --
> 2.39.2
>


-- 
With best wishes
Dmitry