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    SubjectRe: [PATCH v3] dt-bindings: dvfs: Add support for generic performance domains
    Date
    On Wed, 07 Apr 2021 14:59:13 +0100, Sudeep Holla wrote:
    > The CLKSCREW attack [0] exposed security vulnerabilities in energy management
    > implementations where untrusted software had direct access to clock and
    > voltage hardware controls. In this attack, the malicious software was able to
    > place the platform into unsafe overclocked or undervolted configurations. Such
    > configurations then enabled the injection of predictable faults to reveal
    > secrets.
    >
    > Many Arm-based systems used to or still use voltage regulator and clock
    > frameworks in the kernel. These frameworks allow callers to independently
    > manipulate frequency and voltage settings. Such implementations can render
    > systems susceptible to this form of attack.
    >
    > Attacks such as CLKSCREW are now being mitigated by not having direct and
    > independent control of clock and voltage in the kernel and moving that
    > control to a trusted entity, such as the SCP firmware or secure world
    > firmware/software which are to perform sanity checking on the requested
    > performance levels, thereby preventing any attempted malicious programming.
    >
    > With the advent of such an abstraction, there is a need to replace the
    > generic clock and regulator bindings used by such devices with a generic
    > performance domains bindings.
    >
    > [0] https://www.usenix.org/conference/usenixsecurity17/technical-sessions/presentation/tang
    >
    > Link: https://lore.kernel.org/r/20201116181356.804590-1-sudeep.holla@arm.com
    > Cc: Rob Herring <robh+dt@kernel.org>
    > Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
    > Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
    > ---
    >
    > Hi All,
    >
    > Sorry for the delay, I thought I had sent this out last week and it turns
    > out that I had dry-run in my git email command and never removed it. Just
    > noticed now looking for response for this patch on the list to find out
    > that I never sent it out :(.
    >
    > v2[2]->v3:
    > - Dropped required properties
    > - Added non cpu device example
    > - Updated cpu bindings too
    >
    > v1[1]->v2[2]:
    > - Changed to Dual License
    > - Added select: true, enum for #performance-domain-cells and
    > $ref for performance-domain
    > - Changed the example to use real existing compatibles instead
    > of made-up ones
    >
    > [1] https://lore.kernel.org/lkml/20201105173539.1426301-1-sudeep.holla@arm.com
    > [2] https://lore.kernel.org/lkml/20201116181356.804590-1-sudeep.holla@arm.com
    >
    > .../devicetree/bindings/arm/cpus.yaml | 7 ++
    > .../bindings/dvfs/performance-domain.yaml | 80 +++++++++++++++++++
    > 2 files changed, 87 insertions(+)
    > create mode 100644 Documentation/devicetree/bindings/dvfs/performance-domain.yaml
    >

    My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
    on your patch (DT_CHECKER_FLAGS is new in v5.13):

    yamllint warnings/errors:

    dtschema/dtc warnings/errors:
    Documentation/devicetree/bindings/dvfs/performance-domain.example.dt.yaml:0:0: /example-0/performance-controller@12340000: failed to match any schema with compatible: ['qcom,cpufreq-hw']
    /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/dvfs/performance-domain.example.dt.yaml: gpu@2d000000: compatible: 'oneOf' conditional failed, one must be fixed:
    ['arm,mali-t624'] is too short
    'arm,mali-t624' is not one of ['samsung,exynos5250-mali']
    'arm,mali-t624' is not one of ['samsung,exynos5420-mali']
    'arm,mali-t624' is not one of ['allwinner,sun50i-h6-mali']
    'arm,mali-t624' is not one of ['amlogic,meson-gxm-mali', 'realtek,rtd1295-mali']
    'arm,mali-t624' is not one of ['arm,juno-mali']
    'arm,mali-t624' is not one of ['rockchip,rk3288-mali', 'samsung,exynos5433-mali']
    'arm,mali-t624' is not one of ['rockchip,rk3399-mali']
    From schema: /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/gpu/arm,mali-midgard.yaml
    /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/dvfs/performance-domain.example.dt.yaml: gpu@2d000000: 'interrupt-names' is a required property
    From schema: /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/gpu/arm,mali-midgard.yaml
    /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/dvfs/performance-domain.example.dt.yaml: gpu@2d000000: 'clocks' is a required property
    From schema: /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/gpu/arm,mali-midgard.yaml
    /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/dvfs/performance-domain.example.dt.yaml: gpu@2d000000: 'performance-domains' does not match any of the regexes: 'pinctrl-[0-9]+'
    From schema: /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/gpu/arm,mali-midgard.yaml
    /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/dvfs/performance-domain.example.dt.yaml: gpu@2d000000: 'oneOf' conditional failed, one must be fixed:
    'interrupts' is a required property
    'interrupts-extended' is a required property
    From schema: /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/gpu/arm,mali-midgard.yaml

    See https://patchwork.ozlabs.org/patch/1463354

    This check can fail if there are any dependencies. The base for a patch
    series is generally the most recent rc1.

    If you already ran 'make dt_binding_check' and didn't see the above
    error(s), then make sure 'yamllint' is installed and dt-schema is up to
    date:

    pip3 install dtschema --upgrade

    Please check and re-submit.

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