From: Andi Kleen <andi@firstfloor.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
x86@kernel.org, Borislav Petkov <bp@alien8.de>,
Yinghai Lu <yinghai@kernel.org>
Subject: Re: [patch 4/8] x86/tsc: Verify TSC_ADJUST from idle
Date: Mon, 21 Nov 2016 14:57:13 -0800 [thread overview]
Message-ID: <87k2bwxwza.fsf@tassilo.jf.intel.com> (raw)
In-Reply-To: <20161119134017.732180441@linutronix.de> (Thomas Gleixner's message of "Sat, 19 Nov 2016 13:47:37 -0000")
Thomas Gleixner <tglx@linutronix.de> writes:
> When entering idle, it's a good oportunity to verify that the TSC_ADJUST
> MSR has not been tampered with (BIOS hiding SMM cycles). If tampering is
> detected, emit a warning and restore it to the previous value.
idle entry is a time critical code path too, because idle periods are
often very short. rdmsr is a us+ at least. You'll likely make
workloads that do a lot of short sleeps noticeable slower.
If anything load limit it aggressively.
BTW I don't think this situation of SMM tampering with TSC is common
anyways, so it may be simply not worth checking, or perhaps
only with a debug boot option.
-Andi
next prev parent reply other threads:[~2016-11-21 22:57 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-19 13:47 [patch 0/8] x86/tsc: Utilize TSC_ADJUST MSR Thomas Gleixner
2016-11-19 13:47 ` [patch 1/8] x86/tsc: Use X86_FEATURE_TSC_ADJUST in detect_art() Thomas Gleixner
2016-11-29 16:46 ` [tip:x86/timers] " tip-bot for Thomas Gleixner
2016-11-29 18:28 ` tip-bot for Thomas Gleixner
2016-11-19 13:47 ` [patch 2/8] x86/tsc: Detect random warps Thomas Gleixner
2016-11-29 16:46 ` [tip:x86/timers] " tip-bot for Thomas Gleixner
2016-11-29 18:28 ` tip-bot for Thomas Gleixner
2016-11-19 13:47 ` [patch 3/8] x86/tsc: Store and check TSC ADJUST MSR Thomas Gleixner
2016-11-29 16:47 ` [tip:x86/timers] " tip-bot for Thomas Gleixner
2016-11-29 18:29 ` tip-bot for Thomas Gleixner
2017-01-27 13:36 ` [3/8] " Henning Schild
2017-01-30 10:20 ` Thomas Gleixner
2017-01-30 12:13 ` Henning Schild
2017-01-30 13:04 ` Thomas Gleixner
2017-01-30 15:58 ` Borislav Petkov
2016-11-19 13:47 ` [patch 4/8] x86/tsc: Verify TSC_ADJUST from idle Thomas Gleixner
2016-11-20 13:10 ` Peter Zijlstra
2016-11-21 8:16 ` Thomas Gleixner
2016-11-21 11:06 ` Peter Zijlstra
2016-11-29 9:17 ` Thomas Gleixner
2016-11-29 14:25 ` Ingo Molnar
2016-11-21 22:57 ` Andi Kleen [this message]
2016-11-29 16:47 ` [tip:x86/timers] " tip-bot for Thomas Gleixner
2016-11-29 18:29 ` tip-bot for Thomas Gleixner
2016-11-19 13:47 ` [patch 5/8] x86/tsc: Sync test only for the first cpu in a package Thomas Gleixner
2016-11-29 16:48 ` [tip:x86/timers] " tip-bot for Thomas Gleixner
2016-11-29 18:30 ` tip-bot for Thomas Gleixner
2016-11-19 13:47 ` [patch 6/8] x86/tsc: Move sync cleanup to a safe place Thomas Gleixner
2016-11-29 16:48 ` [tip:x86/timers] " tip-bot for Thomas Gleixner
2016-11-29 18:30 ` tip-bot for Thomas Gleixner
2016-11-19 13:47 ` [patch 7/8] x86/tsc: Prepare warp test for TSC adjustment Thomas Gleixner
2016-11-29 16:49 ` [tip:x86/timers] " tip-bot for Thomas Gleixner
2016-11-29 18:31 ` tip-bot for Thomas Gleixner
2016-11-19 13:47 ` [patch 8/8] x86/tsc: Try to adjust TSC if sync test fails Thomas Gleixner
2016-11-29 16:49 ` [tip:x86/timers] " tip-bot for Thomas Gleixner
2016-11-29 18:31 ` tip-bot for Thomas Gleixner
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87k2bwxwza.fsf@tassilo.jf.intel.com \
--to=andi@firstfloor.org \
--cc=bp@alien8.de \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
--cc=yinghai@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.