linux-kernel - Re: [PATCH 9/9] perf/x86: add syfs entry to disable HT bug workaround

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]

Date:	Thu, 5 Jun 2014 17:17:34 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Maria Dimakopoulou <maria.n.dimakopoulou@...il.com>
Cc:	Stephane Eranian <eranian@...gle.com>,
	Matt Fleming <matt@...sole-pimps.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	"mingo@...e.hu" <mingo@...e.hu>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>,
	Jiri Olsa <jolsa@...hat.com>,
	"Yan, Zheng" <zheng.z.yan@...el.com>
Subject: Re: [PATCH 9/9] perf/x86: add syfs entry to disable HT bug workaround

On Thu, Jun 05, 2014 at 05:45:24PM +0300, Maria Dimakopoulou wrote:
> The issue is that the outcoming leaked counts are not compensated
> by the incoming leaked counts of the sibling thread. With the workaround,
> corrupting events are always scheduled with an empty sibling counter.
> This means that their leaked counts are lost. So it is expected to see
> lower counts with the workaround. Note that this is not a side-effect of
> the workaround; leaked counts are expected to be lost with nothing
> measured on the sibling counter in general.
> 
> In a second series we intend to re-integrate the counts for counting mode
> events. The workaround makes this easier because it guarantees
> that the sibling counter is unused, thus its counts are purely leaked
> counts and they can be safely re-integrated.

IIUC, sounds to me like reintegrating the leaked counts from the unused
counter should be part of the workaround too, not a second series...

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
--
--
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/