linux-kernel - Re: intel_pstate divide error with v3.13-rc4-256-gb7000ad

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Message-ID: <4410803.FiVxaMNxvJ@vostro.rjw.lan>
Date:	Sat, 04 Jan 2014 22:38:33 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Gleb Natapov <gleb@...antech.com>
Cc:	Paolo Bonzini <pbonzini@...hat.com>,
	Dirk Brandewie <dirk.brandewie@...il.com>,
	Kashyap Chamarthy <kchamart@...hat.com>,
	Josh Boyer <jwboyer@...oraproject.org>,
	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	"Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>,
	"Richard W.M. Jones" <rjones@...hat.com>
Subject: Re: intel_pstate divide error with v3.13-rc4-256-gb7000ad

On Saturday, January 04, 2014 07:48:13 PM Gleb Natapov wrote:
> On Sat, Jan 04, 2014 at 06:38:59PM +0100, Paolo Bonzini wrote:
> > Il 04/01/2014 15:38, Rafael J. Wysocki ha scritto:
> > > Well, it's just a sanity check and it makes the problem go away for the reporter.
> > > 
> > >> > Your patch is welcome but perhaps it should have a WARN_ON too.
> > > It has been pulled in already, so the WARN_ON() can only be added via a separate
> > > patch now.  Would you like to prepare that patch?
> > 
> > Yes, I'll add it together with the CPUID check.  I'll send the patch so
> > that it can get into 3.14.
> > 
> CPUID check, while correct, will sweep the problem under the rug. Current
> Linux logic should detect non working pstate in KVM. We should look into
> why this is not happening for nested.

I agree.  It's better not to use CPUID for that in my opinion.

Thanks!

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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