MIME-Version: 1.0
In-Reply-To: <20150807083428.GB18673@twins.programming.kicks-ass.net>
References: <tip-b7b7c7821d932ba18ef6c8eafc8536066b4c2ef4@git.kernel.org>
 <CALCETrXffVT=KQpURGLEAXH5x6KxXhYuicGgk3hmF8-QGT81jw@mail.gmail.com>
 <37D7C6CF3E00A74B8858931C1DB2F077018D16F1@SHSMSX103.ccr.corp.intel.com>
 <CALCETrXUdBs==s-dBfugshyFdG_nBn=qd2MKYLwmXYx_r43Vvg@mail.gmail.com>
 <37D7C6CF3E00A74B8858931C1DB2F077018D206A@SHSMSX103.ccr.corp.intel.com>
 <CALCETrXP0-jRiq_qz=hwPxjMxGrbke9rtembh4_XBq-vq+cPNg@mail.gmail.com>
 <37D7C6CF3E00A74B8858931C1DB2F077018D2103@SHSMSX103.ccr.corp.intel.com>
 <20150806152151.GG25159@twins.programming.kicks-ass.net> <CALCETrUotdmF3qTrLeyEJbmS4h2hxXF021dXbS3RWZwH55+YAA@mail.gmail.com>
 <20150806155943.GH25159@twins.programming.kicks-ass.net> <20150807083428.GB18673@twins.programming.kicks-ass.net>
From: Andy Lutomirski <luto@amacapital.net>
Date: Sun, 9 Aug 2015 19:12:23 -0700
Message-ID: <CALCETrVMSWnHkvjXH8zc3nKuTarADvBO=YEof4dkAzHsmc6jKg@mail.gmail.com>
Subject: Re: [tip:perf/core] perf/x86: Add an MSR PMU driver
To: Peter Zijlstra <peterz@infradead.org>
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>
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1240
Lines: 31

On Fri, Aug 7, 2015 at 1:34 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Thu, Aug 06, 2015 at 05:59:43PM +0200, Peter Zijlstra wrote:
>> 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.
>
> This then..
>

LGTM on brief inspection.

--Andy
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/