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From: Peter Zijlstra <peterz@infradead.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: "Liang, Kan" <kan.liang@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Andrew Lutomirski <luto@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	"linux-tip-commits@vger.kernel.org" 
	<linux-tip-commits@vger.kernel.org>
Subject: Re: [tip:perf/core] perf/x86: Add an MSR PMU driver
Date: Thu, 6 Aug 2015 17:59:43 +0200	[thread overview]
Message-ID: <20150806155943.GH25159@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <CALCETrUotdmF3qTrLeyEJbmS4h2hxXF021dXbS3RWZwH55+YAA@mail.gmail.com>

On Thu, Aug 06, 2015 at 08:30:08AM -0700, Andy Lutomirski wrote:
> On Thu, Aug 6, 2015 at 8:21 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> > On Tue, Aug 04, 2015 at 08:39:27PM +0000, Liang, Kan wrote:
> > -       default:
> > -               err = -ENOTSUPP;
> > +               if (!msr[i].test() || rdmsrl_safe(msr[i].msr, &val))
> > +                       msr[i].attr = NULL;
> 
> IIRC rdmsrl_safe literally never fails under QEMU TCG, and I'm not

*sigh* the borkage never stops does it :-(

> entirely sure what happens under KVM if emulation kicks in.  It might
> pay to keep the model check for the non-architectural stuff, or at
> least check for a nonzero return value.

Of course, 0 might be a valid value.. Esp. for the SMI counter.

  reply	other threads:[~2015-08-06 15:59 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-20 15:49 [PATCH RFC V2 1/1] x86, perf: Add a freq pmu driver Kan Liang
2015-07-21  3:10 ` Stephane Eranian
2015-07-21  6:01   ` Andy Lutomirski
2015-07-21  6:21     ` Stephane Eranian
2015-07-21  6:23       ` Andy Lutomirski
2015-07-21  9:55         ` Peter Zijlstra
2015-07-21  9:55 ` Peter Zijlstra
2015-07-23 15:44   ` Stephane Eranian
2015-07-23 15:52     ` Andy Lutomirski
2015-07-23 16:00       ` Stephane Eranian
2015-07-23 17:25     ` Andi Kleen
2015-07-26 16:31 ` Jiri Olsa
2015-07-27 17:40   ` Andy Lutomirski
2015-08-04  9:01 ` [tip:perf/core] perf/x86: Add an MSR PMU driver tip-bot for Andy Lutomirski
2015-08-04 14:50   ` Andy Lutomirski
2015-08-04 15:03     ` Liang, Kan
2015-08-04 18:00       ` Andy Lutomirski
2015-08-04 18:11         ` Liang, Kan
2015-08-04 18:13           ` Andy Lutomirski
2015-08-04 20:39             ` Liang, Kan
2015-08-06 15:21               ` Peter Zijlstra
2015-08-06 15:30                 ` Andy Lutomirski
2015-08-06 15:59                   ` Peter Zijlstra [this message]
2015-08-07  8:34                     ` Peter Zijlstra
2015-08-10  2:12                       ` Andy Lutomirski
2015-08-10 14:02                       ` Liang, Kan
2015-08-10 14:24                         ` Peter Zijlstra
2015-08-06 17:44                 ` Liang, Kan
2015-08-10 11:19   ` Jiri Olsa
2015-08-10 11:42     ` Peter Zijlstra

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