linux-kernel - Re: [RFC PATCH] tsc: synchronize TSCs on buggy Intel Xeon E5 CPUs with offset error

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20151113204338.GA9928@worktop.ger.corp.intel.com>
Date:	Fri, 13 Nov 2015 21:43:38 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Gratian Crisan <gratian.crisan@...com>
Cc:	Josh Hunt <joshhunt00@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...hat.com>,
	"H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Borislav Petkov <bp@...en8.de>, Josh Cartwright <joshc@...com>,
	gratian@...il.com
Subject: Re: [RFC PATCH] tsc: synchronize TSCs on buggy Intel Xeon E5 CPUs
 with offset error

On Wed, Nov 11, 2015 at 09:41:25AM -0600, Gratian Crisan wrote:
> I also wrote a small C utility[1], with a bit of code borrowed from the
> kernel, for reading the TSC on all CPUs. It starts a high priority
> thread per CPU, tries to synchronize them and prints out the TSC values
> and their offset with regards to CPU0.
> It can be called from a SysV init shell script[2] at the beginning of
> the boot process and right before a reboot to save the values in a file.

Could you also read and print TSC_ADJUST (msr 0x3b) ? This would tell us
if for example your BIOS messed it up.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/