linux-kernel - Re: [PATCH v4] dt-bindings: dvfs: Add support for generic performance domains

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Message-ID: <CAL_JsqK6B40D8dRu8KoOsx6eSzRXx6KsSEu5mjDokPEAy+p4oA@mail.gmail.com>
Date:   Mon, 17 May 2021 14:17:05 -0500
From:   Rob Herring <robh@...nel.org>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Hector Yuan <hector.yuan@...iatek.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Subject: Re: [PATCH v4] dt-bindings: dvfs: Add support for generic performance domains

On Mon, May 17, 2021 at 10:55 AM Sudeep Holla <sudeep.holla@....com> 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@...nel.org>
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>

Reviewed-by: Rob Herring <robh@...nel.org>