linux-kernel - Re: unchecked MSR access error in throttle_active

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Message-ID: <20191128185607.GA3726@owl.dominikbrodowski.net>
Date:   Thu, 28 Nov 2019 19:56:07 +0100
From:   Dominik Brodowski <linux@...inikbrodowski.net>
To:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc:     Borislav Petkov <bp@...en8.de>, Tony Luck <tony.luck@...el.com>,
        linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: unchecked MSR access error in throttle_active_work()

On Thu, Nov 28, 2019 at 06:51:42AM -0800, Srinivas Pandruvada wrote:
> On Thu, 2019-11-28 at 11:29 +0100, Dominik Brodowski wrote:
> > On Thu, Nov 28, 2019 at 10:44:19AM +0100, Borislav Petkov wrote:
> > > On Thu, Nov 28, 2019 at 09:54:47AM +0100, Dominik Brodowski wrote:
> > > > On most recent mainline kernels (such as 5.5-rc0 up to
> > > > a6ed68d6468b), I see
> > > > the following output in dmesg during startup:
> > > > 
> > > > [   78.016676] unchecked MSR access error: WRMSR to 0x19c (tried
> > > > to write 0x00000000880f3a80) at rIP: 0xffffffff84ab5742
> > > > (throttle_active_work+0xf2/0x230)
> > > > [   78.016686] Call Trace:
> > > > [   78.016694]  process_one_work+0x247/0x590
> > > > [   78.016703]  worker_thread+0x50/0x3b0
> > > > [   78.016710]  kthread+0x10a/0x140
> > > > [   78.016715]  ? process_one_work+0x590/0x590
> > > > [   78.016735]  ? kthread_park+0x90/0x90
> > > > [   78.016740]  ret_from_fork+0x3a/0x50
> > > > 
> > > > Any clues?
> > > 
> > > Most likely
> > > 
> > > f6656208f04e ("x86/mce/therm_throt: Optimize notifications of
> > > thermal throttle")
> > > 
> > > I guess we're missing some X86_FEATURE_ check for that MSR to
> > > exist.
> > 
> > Thanks. FWIW, it's a i7-8650U.
> > 
> Please try the attached patch. 

Seems to work fine now. Thanks!

	Dominik