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From: Peter Zijlstra <peterz@infradead.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	x86-ml <x86@kernel.org>, lkml <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] x86/msr: Filter MSR writes
Date: Fri, 12 Jun 2020 22:39:35 +0200	[thread overview]
Message-ID: <20200612203935.GH2497@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200612174801.GE22660@zn.tnic>

On Fri, Jun 12, 2020 at 07:48:01PM +0200, Borislav Petkov wrote:
> On Fri, Jun 12, 2020 at 10:20:03AM -0700, Linus Torvalds wrote:
> > Since you already added the filtering, this looks fairly sane.
> > 
> > IOW, what MSR's do we expect people to maybe write to normally? You
> > added MSR_IA32_ENERGY_PERF_BIAS as an allowed MST, maybe there are
> > others?
> 
> Right, this MSR is being written by cpupower in tools/. My search was
> confined within the kernel source only so there very likely are others.

So that tool writing to /dev/msr has already caused pain; the direct
result is that the intel pstate driver doesn't want to use an MSR shadow
variable to avoid RDMSR because that'd loose input.

https://lkml.org/lkml/2019/3/25/310

(sorry, that's what google found me)

So ideally we'd just disallow it too. It already has a sysfs file (per
those patches):

  Documentation/admin-guide/pm/intel_epb.rst

  parent reply	other threads:[~2020-06-12 20:39 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-12 10:50 Borislav Petkov
2020-06-12 16:34 ` Sean Christopherson
2020-06-12 16:46   ` Borislav Petkov
2020-06-12 16:57     ` Sean Christopherson
2020-06-12 17:03       ` Borislav Petkov
2020-06-12 17:43         ` Sean Christopherson
2020-06-12 17:52           ` Borislav Petkov
2020-06-12 17:20 ` Linus Torvalds
2020-06-12 17:48   ` Borislav Petkov
2020-06-12 19:47     ` Borislav Petkov
2020-06-12 20:39     ` Peter Zijlstra [this message]
2020-06-13  5:40       ` Tony Luck
2020-06-13  9:39       ` Borislav Petkov
2020-06-13 15:48 ` [PATCH -v2] " Borislav Petkov
2020-06-15  6:38   ` [PATCH -v2.1] " Borislav Petkov
2020-06-25  5:51     ` Sean Christopherson
2020-06-25  8:37       ` Borislav Petkov
2020-07-14 12:19     ` Chris Down
2020-07-14 15:47       ` Borislav Petkov
2020-07-14 16:04         ` Chris Down
2020-07-14 16:46           ` Luck, Tony
2020-07-14 16:58             ` Borislav Petkov
2020-07-14 17:02             ` Chris Down
2020-07-14 16:56           ` Borislav Petkov
2020-07-14 17:04             ` Chris Down
2020-07-14 18:52             ` Srinivas Pandruvada
2020-07-15  4:26               ` Borislav Petkov
2020-07-14 19:17           ` Matthew Garrett
2020-11-17 21:00             ` Mathieu Chouquet-Stringer
2020-11-17 21:20               ` Borislav Petkov
2020-11-18  8:58                 ` Mathieu Chouquet-Stringer
2020-11-18  9:09                 ` Mathieu Chouquet-Stringer
2020-11-18 11:50                   ` Borislav Petkov
2020-11-18 14:04                     ` [PATCH] " Mathieu Chouquet-Stringer
2020-11-18 17:50                       ` Borislav Petkov
2020-11-19 10:53                         ` Mathieu Chouquet-Stringer
2020-11-25 21:41                           ` Mathieu Chouquet-Stringer
2020-11-26 10:03                           ` Borislav Petkov
2020-11-17 21:21               ` [PATCH -v2.1] " Matthew Garrett
2020-11-17 21:22                 ` Matthew Garrett
2020-11-18  9:02                   ` Mathieu Chouquet-Stringer
2020-06-17 15:06 ` [tip: x86/misc] " tip-bot2 for Borislav Petkov
2020-06-25  8:45 ` tip-bot2 for Borislav Petkov

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