linux-kernel - Re: "Force HWP min perf before offline" triggers unchecked MSR access errors

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Date:   Tue, 29 Oct 2019 15:15:16 -0700
From:   Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     Qian Cai <cai@....pw>, "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Chen Yu <yu.c.chen@...el.com>, Len Brown <lenb@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: "Force HWP min perf before offline" triggers unchecked MSR
 access errors

On Tue, 2019-10-29 at 15:13 -0700, Srinivas Pandruvada wrote:
> On Tue, 2019-10-29 at 18:01 -0400, Qian Cai wrote:
> > > On Oct 29, 2019, at 5:47 PM, Rafael J. Wysocki <rafael@...nel.org
> > > >
> > > wrote:
> > > 
> > > The MSR_IA32_ENERGY_PERF_BIAS MSR appears to be not present,
> > > which
> > > should be caught by the X86_FEATURE_EPB check in
> > > intel_pstate_set_epb().
> > > 
> > > Do you run this in a guest perchance?
> > 
> > No, it is a baremetal HPE server. The dmesg does say something like
> > energy perf bias changed from performance to normal, and the
> > cpuflag
> > contains epb which I thought that would pass the feature check? I
> > could upload the whole dmesg a bit later if that helps.
> 
> Try the attached change. You have a Skylake server with no EPP
> support.
> This is odd.
> 
Sorry.
Ignore the previous one. It had some unrelated change.

> Thanks,
> Srinivas
> 

View attachment "epb_power.diff" of type "text/x-patch" (515 bytes)