Messages in this thread | | | Date | Mon, 29 Jun 2015 11:58:53 +0100 | From | Matt Fleming <> | Subject | Re: [PATCH] x86, msr: Allow read access to /dev/cpu/X/msr |
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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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