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

[Ingo Molnar <mingo@kernel.org>]

* Henrique de Moraes Holschuh <hmh@hmh.eng.br> wrote:

> On Sun, 28 Jun 2015, Prarit Bhargava wrote:
>
> > 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 only way to make MSR access safe is to allow it only by whitelisting. The 
> x86 platform restricts all MSR access to ring 0 for a damn good reason.

Exactly.

We also want to document them along the way: just exposing all doesn't achieve 
that.

> Also, such a whitelist would most likely need to be vendor and model-aware, and 
> to differentiate "allow reads" from "allow writes"...

Initially it should only allow reads - which I believe fully meets turbostat's 
needs.

Thanks,

	Ingo