linux-kernel - Re: [PATCH 2/2] PM / arch: x86: MSR_IA32_ENERGY_PERF

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Date:   Mon, 25 Mar 2019 12:32:18 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     x86 <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
        Len Brown <len.brown@...el.com>,
        Linux PM <linux-pm@...r.kernel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Laura Abbott <labbott@...oraproject.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Simon Schricker <sschricker@...e.de>,
        Borislav Petkov <bp@...e.de>, Hannes Reinecke <hare@...e.de>
Subject: Re: [PATCH 2/2] PM / arch: x86: MSR_IA32_ENERGY_PERF_BIAS sysfs
 interface

On Thu, Mar 21, 2019 at 11:20:17PM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> The Performance and Energy Bias Hint (EPB) is expected to be set by
> user space through the generic MSR interface, but that interface is
> not particularly nice and there are security concerns regarding it,
> so it is not always available.
> 
> For this reason, add a sysfs interface for reading and updating the
> EPB, in the form of a new attribute, energy_perf_bias, located
> under /sys/devices/system/cpu/cpu#/power/ for online CPUs that
> support the EPB feature.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>  Documentation/ABI/testing/sysfs-devices-system-cpu |   18 ++++
>  Documentation/admin-guide/pm/intel_epb.rst         |   27 ++++++
>  arch/x86/kernel/cpu/intel_epb.c                    |   93 ++++++++++++++++++++-
>  3 files changed, 134 insertions(+), 4 deletions(-)

Acked-by: Borislav Petkov <bp@...e.de>

-- 
Regards/Gruss,
    Boris.

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