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

[Matt Fleming]

On Sun, 28 Jun, at 12:10:49PM, Henrique de Moraes Holschuh 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.

Blacklisting also breaks horribly if you run old kernels on new
hardware.

We need to "fail-closed" if someone tries to access an MSR the kernel
doesn't know about.

-- 
Matt Fleming, Intel Open Source Technology Center
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