Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1754225Ab1FOTEu (ORCPT <rfc822;w@1wt.eu>);
	Wed, 15 Jun 2011 15:04:50 -0400
Received: from rcsinet10.oracle.com ([148.87.113.121]:28936 "EHLO
	rcsinet10.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1753842Ab1FOTEq (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Wed, 15 Jun 2011 15:04:46 -0400
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: linux-kernel@vger.kernel.org, davej@redhat.com, tglx@linutronix.de,
        mingo@redhat.com, hpa@zytor.com, x86@kernel.org,
        cpufreq@vger.kernel.org
Subject: [PATCH] cpufreq bug fixes (stable/cpufreq.bugfixes) for 3.0 (or 3.1).
Date: Wed, 15 Jun 2011 15:01:58 -0400
Message-Id: <1308164520-14145-1-git-send-email-konrad.wilk@oracle.com>
X-Mailer: git-send-email 1.7.4.1
X-Source-IP: rtcsinet22.oracle.com [66.248.204.30]
X-CT-RefId: str=0001.0A090209.4DF901BC.00CA:SCFSTAT5015188,ss=1,fgs=0
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 2577
Lines: 55

The two patches attached make the cpufreq and powernowk8 driver more robust on
badly behaving machines (or hypervisors not passing through proper rmsdr calls).

Specifically during the testing of v3.0-rc2, Tobias found a peculiar issue with
his AMD machine: http://mid.gmane.org/20110613202622.GC20616@yumi.tdiedrich.de

It looks as the Xen hypervisor lacks passthrough RDMSR entries for the PowerNow K8
voltage settings (MSR_FIDVID_STATUS and MSR_FIDVID_CTL) resulting in the writes/reads
giving the value zero. The end result being that the cpufreq stats code BUG()s on
incorrect index of the freq table.

The patches are also located at:

git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git stable/cpufreq.bugfixes

The crash looks as follow:

powernow-k8: Found 1 AMD Athlon(tm) 64 Processor 3700+ (1 cpu cores) (version 2.20.00)
powernow-k8: fid 0x2 (1000 MHz), vid 0x12
powernow-k8: fid 0xa (1800 MHz), vid 0xa
powernow-k8: fid 0xc (2000 MHz), vid 0x8
powernow-k8: fid 0xe (2200 MHz), vid 0x8
Marking TSC unstable due to cpufreq changes
powernow-k8: fid trans failed, fid 0x2, curr 0x0
BUG: unable to handle kernel paging request at ffff880807e07b78
IP: [<ffffffff81479163>] cpufreq_stats_update+0x46/0x5b
.. snip..
Pid: 1, comm: swapper Not tainted 3.0.0-rc2 #45 MICRO-STAR INTERNATIONAL CO., LTD MS-7094/MS-7094
..snip..
Call Trace:
 [<ffffffff81479248>] cpufreq_stat_notifier_trans+0x48/0x7c
 [<ffffffff81095d68>] notifier_call_chain+0x32/0x5e
 [<ffffffff81095e6b>] __srcu_notifier_call_chain+0x47/0x63
 [<ffffffff81095e96>] srcu_notifier_call_chain+0xf/0x11
 [<ffffffff81477e7a>] cpufreq_notify_transition+0x111/0x134
 [<ffffffff8147b0d4>] powernowk8_target+0x53b/0x617
 [<ffffffff8147723a>] __cpufreq_driver_target+0x2e/0x30
 [<ffffffff8147a127>] cpufreq_governor_dbs+0x339/0x356
 [<ffffffff81477394>] __cpufreq_governor+0xa8/0xe9
 [<ffffffff81477525>] __cpufreq_set_policy+0x132/0x13e
 [<ffffffff8147848d>] cpufreq_add_dev_interface+0x272/0x28c


Konrad Rzeszutek Wilk (2):
      [CPUFREQ] powernow-k8: Don't notify of successful transition if we failed.
      [CPUFREQ]: Don't set stat->last_index to -1 if the pol->cur has incorrect value.

 arch/x86/kernel/cpu/cpufreq/powernow-k8.c |    7 ++++++-
 drivers/cpufreq/cpufreq_stats.c           |    8 +++++---
 2 files changed, 11 insertions(+), 4 deletions(-)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/