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

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Date:   Thu, 28 Nov 2019 11:29:30 +0100
From:   Dominik Brodowski <linux@...inikbrodowski.net>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        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 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.

Best,
	Dominik