linux-kernel - Re: [perf] unchecked MSR access error: WRMSR to 0x689 in intel_pmu_lbr

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Date:   Tue, 12 Jul 2022 17:26:23 -0400 (EDT)
From:   Vince Weaver <vincent.weaver@...ne.edu>
To:     Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
cc:     Vince Weaver <vincent.weaver@...ne.edu>,
        "Liang, Kan" <kan.liang@...ux.intel.com>,
        linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>
Subject: Re: [perf] unchecked MSR access error: WRMSR to 0x689 in
 intel_pmu_lbr_restore

On Tue, 12 Jul 2022, Pawan Gupta wrote:

> On Tue, Jul 12, 2022 at 03:39:56PM -0400, Vince Weaver wrote:
> It appears this CPU does not support TSX feature (or disabling TSX). If
> the bug is easy to reproduce, bisecting can help.

I thought TSX was disabled via firmware update for all Haswell machines?

In any case, the fuzzer is triggering the
	unchecked MSR access error: WRMSR to 0x689
in intel_pmu_lbr_restore.  So either this is a false error and should be 
disabled, or else it's a real issue and should be fixed.

Unfortunately the fuzzer can take up to a few days to trigger the message 
(it's not easily repeatable) so doing a kernel bisect would take a very 
long time.

Vince