linux-kernel - Re: [PATCH] x86, msr: Allow read access to /dev/cpu/X/msr

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Date:	Mon, 29 Jun 2015 12:51:47 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Prarit Bhargava <prarit@...hat.com>,
	Andy Lutomirski <luto@...capital.net>
CC:	Ingo Molnar <mingo@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, X86 ML <x86@...nel.org>,
	Len Brown <len.brown@...el.com>,
	Dasaratharaman Chandramouli 
	<dasaratharaman.chandramouli@...el.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Borislav Petkov <bp@...en8.de>,
	Andy Lutomirski <luto@...nel.org>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Brian Gerst <brgerst@...il.com>,
	Arnaldo Carvalho de Melo <acme@...radead.org>
Subject: Re: [PATCH] x86, msr: Allow read access to /dev/cpu/X/msr

On 06/28/2015 07:34 AM, Prarit Bhargava wrote:
>>
>> Seriously, though, it would be straightforward to make it handle a
>> more general list, complete with non-architectural stuff (such as the
>> upcoming PPERF in Skylake).
> 
> Is it easier to blacklist MSRs we don't want generally exposed, or only expose
> the ones that we think are safe?  That's sort of a devil's advocate sort of
> question ;) and I'm wondering what the shorter list is.
> 

The second is the only option.  Blacklisting MSRs is not safe, as you
have no idea what new MSRs might be introduced.

	-hpa


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