linux-kernel - Re: [PATCH] x86/rapl: Do not load in a guest

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Date:	Fri, 4 Dec 2015 10:37:31 -0800
From:	Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Paolo Bonzini <pbonzini@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Amy Wiles <amy.l.wiles@...el.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Hannes Reinecke <hare@...e.de>, jacob.jun.pan@...ux.intel.com
Subject: Re: [PATCH] x86/rapl: Do not load in a guest

On Fri, 4 Dec 2015 19:28:07 +0100
Borislav Petkov <bp@...en8.de> wrote:

> On Fri, Dec 04, 2015 at 10:16:10AM -0800, Jacob Pan wrote:
> > CPU model detection is the first level checking.  
> 
> And in the case of RAPL, the only checking you can do. This is why it
> should've had a CPUID bit.
> 
I am 200% with you, all I can say is we are working on it. Look at the
pain in the driver for dealing with various quirks.

> > The error is about no valid domains (e.g. counters not working). So
> > the error on minnowboard board could be a real problem if you expect
> > to use RAPL.  
> 
> Right, and if you need to disable it there, you would need to add a
> quirk table looking at DMI strings or so. A CPUID bit might've been a
> bit better if BIOS update would clear it on those boards. Then, sw
> won't even try to load there.
who is gonna collect all the DMI strings? I don't think this is
scalable.
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