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

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Date:   Tue, 29 Oct 2019 22:47:23 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Qian Cai <cai@....pw>
Cc:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        "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, Oct 29, 2019 at 9:55 PM Qian Cai <cai@....pw> wrote:
>
> The commit af3b7379e2d7 ("cpufreq: intel_pstate: Force HWP min perf before
> offline") triggers an error below while doing CPU hotplug. Reverted it (on the
> top of the linux-next) fixed it.
>
> https://raw.githubusercontent.com/cailca/linux-mm/master/x86.config

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?