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

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Date:	Fri, 4 Dec 2015 11:56:17 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Paolo Bonzini <pbonzini@...hat.com>
Cc:	Ingo Molnar <mingo@...nel.org>, "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>,
	Jacob Pan <jacob.jun.pan@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] x86/rapl: Do not load in a guest

On Fri, Dec 04, 2015 at 11:41:03AM +0100, Paolo Bonzini wrote:
> No, please don't.  Why do you need a wrmsr instead of a rdmsr?  If
> there's no RAPL domains, the device doesn't load.  On hypervisors,
> reading random MSRs is generally safe.

Well, we could not do anything, sure, that's an option too. It would
only be the annoying error message. Which is

	pr_err("no valid rapl domains found in package %d\n", rp->id);

I guess we can tone that down as apparently it is not an error to
not have valid rapl domains anymore. Maybe kill it altogether:
rapl_detect_topology() will propagate the error and the driver won't
load...

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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