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

[Rob Herring]

On Mon, May 17, 2021 at 10:55 AM Sudeep Holla <sudeep.holla@xxxxxxx> 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@xxxxxxx
> Cc: Rob Herring <robh+dt@xxxxxxxxxx>
> Acked-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>

Reviewed-by: Rob Herring <robh@xxxxxxxxxx>