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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
Powered by JetHome