From: Thomas Gleixner <tglx@linutronix.de>
To: Borislav Petkov <bp@alien8.de>
Cc: Stephane Eranian <eranian@google.com>, x86-ml <x86@kernel.org>,
linux-kernel@vger.kernel.org, peterz@infradead.org,
mingo@elte.hu, ak@linux.intel.com, jolsa@redhat.com,
kan.liang@intel.com, maria.n.dimakopoulou@gmail.com
Subject: Re: [PATCH v3 13/13] perf/x86: add syfs entry to disable HT bug workaround
Date: Tue, 18 Nov 2014 01:31:38 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.11.1411180115420.3909@nanos> (raw)
In-Reply-To: <20141117235841.GD25157@pd.tnic>
On Tue, 18 Nov 2014, Borislav Petkov wrote:
> On Tue, Nov 18, 2014 at 12:38:14AM +0100, Thomas Gleixner wrote:
> > Well a bitmask is a pretty indescriptive item as well. Putting my user
> > hat on: Where is the documentation for the bits?
>
> $ cat /sys/devices/system/cpu/bugs
> 0xXXXXXX - currently enabled workarounds are the set bits.
> bit 0: workaround for bug#blabla
> bit 1: workaround for bug#1
> bit 2: workaround for bug#2; remember to do <bla> before disabling workaround
> ...
> bits n-63 are reserved, cannot be set and RAZ.
You sure that 64 are enough?
You need to create stable but numbers, i.e. each bug gets a fixed but
number whethr it affects the machine or not. Otherwise you will drive
admins completely nuts.
> This will be issued when user cats the sysfs file.
That might work as well, though you want that to be:
/sys/devices/system/cpu/bugs/
/sys/devices/system/cpu/bugs/status
/sys/devices/system/cpu/bugs/enable_workaround
/sys/devices/system/cpu/bugs/disable_workaround
The latter two take a bit number rather than a magic mask.
So while it looks less effort to implement and extend in the first
place I think, that a bit of infrastructure work will make the
explicit scheme I proposed before a no brainer to maintain and extend,
but I cannot judge what's more intuitive to use.
Thanks,
tglx
next prev parent reply other threads:[~2014-11-18 0:31 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-17 19:06 [PATCH v3 00/13] perf/x86: implement HT counter corruption workaround Stephane Eranian
2014-11-17 19:06 ` [PATCH v3 01/13] perf,x86: rename er_flags to flags Stephane Eranian
2015-04-02 18:41 ` [tip:perf/core] perf/x86: Rename x86_pmu::er_flags to 'flags' tip-bot for Stephane Eranian
2014-11-17 19:06 ` [PATCH v3 02/13] perf/x86: vectorize cpuc->kfree_on_online Stephane Eranian
2015-04-02 18:41 ` [tip:perf/core] perf/x86: Vectorize cpuc->kfree_on_online tip-bot for Stephane Eranian
2014-11-17 19:06 ` [PATCH v3 03/13] perf/x86: add 3 new scheduling callbacks Stephane Eranian
2015-04-02 18:42 ` [tip:perf/core] perf/x86: Add " tip-bot for Maria Dimakopoulou
2014-11-17 19:06 ` [PATCH v3 04/13] perf/x86: add index param to get_event_constraint() callback Stephane Eranian
2015-04-02 18:42 ` [tip:perf/core] perf/x86: Add 'index' " tip-bot for Stephane Eranian
2014-11-17 19:06 ` [PATCH v3 05/13] perf/x86: add cross-HT counter exclusion infrastructure Stephane Eranian
2015-04-02 18:42 ` [tip:perf/core] perf/x86/intel: Add " tip-bot for Maria Dimakopoulou
2014-11-17 19:06 ` [PATCH v3 06/13] perf/x86: implement cross-HT corruption bug workaround Stephane Eranian
2015-04-02 18:43 ` [tip:perf/core] perf/x86/intel: Implement " tip-bot for Maria Dimakopoulou
2014-11-17 19:06 ` [PATCH v3 07/13] perf/x86: enforce HT bug workaround for SNB/IVB/HSW Stephane Eranian
2015-04-02 18:43 ` [tip:perf/core] perf/x86/intel: Enforce HT bug workaround for SNB /IVB/HSW tip-bot for Maria Dimakopoulou
2014-11-17 19:07 ` [PATCH v3 08/13] perf/x86: enforce HT bug workaround with PEBS for SNB/IVB/HSW Stephane Eranian
2015-04-02 18:43 ` [tip:perf/core] perf/x86/intel: Enforce " tip-bot for Maria Dimakopoulou
2014-11-17 19:07 ` [PATCH v3 09/13] perf/x86: fix intel_get_event_constraints() for dynamic constraints Stephane Eranian
2015-04-02 18:43 ` [tip:perf/core] perf/x86/intel: Fix " tip-bot for Stephane Eranian
2014-11-17 19:07 ` [PATCH v3 10/13] perf/x86: limit to half counters to avoid exclusive mode starvation Stephane Eranian
2015-04-02 18:44 ` [tip:perf/core] perf/x86/intel: Limit to half counters when the HT workaround is enabled, " tip-bot for Stephane Eranian
2014-11-17 19:07 ` [PATCH v3 11/13] watchdog: add watchdog enable/disable all functions Stephane Eranian
2015-04-02 18:44 ` [tip:perf/core] watchdog: Add watchdog enable/ disable " tip-bot for Stephane Eranian
2014-11-17 19:07 ` [PATCH v3 12/13] perf/x86: make HT bug workaround conditioned on HT enabled Stephane Eranian
2015-04-02 18:44 ` [tip:perf/core] perf/x86/intel: Make the HT bug workaround conditional " tip-bot for Stephane Eranian
2014-11-17 19:07 ` [PATCH v3 13/13] perf/x86: add syfs entry to disable HT bug workaround Stephane Eranian
2014-11-17 23:02 ` Borislav Petkov
2014-11-17 23:38 ` Thomas Gleixner
2014-11-17 23:58 ` Borislav Petkov
2014-11-18 0:31 ` Thomas Gleixner [this message]
2014-11-18 15:29 ` Stephane Eranian
2014-11-18 15:43 ` Borislav Petkov
2014-11-18 16:37 ` Stephane Eranian
2014-11-18 16:42 ` Borislav Petkov
2014-11-18 15:01 ` Maria Dimakopoulou
2014-11-18 15:12 ` Borislav Petkov
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