From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760046AbZKGC5a (ORCPT ); Fri, 6 Nov 2009 21:57:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759964AbZKGC53 (ORCPT ); Fri, 6 Nov 2009 21:57:29 -0500 Received: from mga09.intel.com ([134.134.136.24]:17461 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759873AbZKGC52 (ORCPT ); Fri, 6 Nov 2009 21:57:28 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.44,697,1249282800"; d="scan'208";a="567355168" Subject: Re: [PATCH] x86, therm: Only read the initial value of thermal LVT entry on BSP From: Suresh Siddha Reply-To: Suresh Siddha To: Yong Wang Cc: Ingo Molnar , "H. Peter Anvin" , "linux-kernel@vger.kernel.org" In-Reply-To: <20091107001736.GA30790@ywang-moblin2.bj.intel.com> References: <20091107001736.GA30790@ywang-moblin2.bj.intel.com> Content-Type: text/plain Organization: Intel Corp Date: Fri, 06 Nov 2009 18:56:05 -0800 Message-Id: <1257562565.4083.485.camel@sbs-t61.sc.intel.com> Mime-Version: 1.0 X-Mailer: Evolution 2.26.3 (2.26.3-1.fc11) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2009-11-06 at 16:17 -0800, Yong Wang wrote: > Only read the initial value of thermal LVT entry on BSP. The initial > value of thermal LVT entries on all APs always reads 0x10000 because > APs are woken up by BSP issuing INIT-SIPI-SIPI sequence to them and > LVT registers are reset to 0s except for mask bits which are set to > 1s when APs receive INIT IPI. > > Also restore the value that BIOS has programmed on AP based on BSP's > info we saved since BIOS is always setting the same value for all > threads/cores. Yong, I have appended a new patch with an enhanced change log and subject. In future, when you modify and post another version of the patch, can you please update the patch version and elaborate what has changed, why etc, so that it will be easier for the reviewers. Ingo/Peter, please review and queue this patch from Yong. Thanks. --- From: Yong Wang Subject: x86: under bios control, restore AP's APIC_LVTTHMR to the BSP value On platforms where bios handles the thermal monitor interrupt, APIC_LVTTHMR on each logical CPU is programmed to generate a SMI and OS can't touch it. Unfortunately AP bringup sequence using INIT-SIPI-SIPI clear all the LVT entries except the mask bit. Essentially this results in all LVT entries including the thermal monitoring interrupt set to masked (clearing the bios programmed value for APIC_LVTTHMR). And this leads to kernel take over the thermal monitoring interrupt on AP's but not on BSP (leaving the bios programmed value only on BSP). As a result of this, we have seen system hangs when the thermal monitoring interrupt is generated. Fix this by reading the initial value of thermal LVT entry on BSP and if bios has taken over the control, then program the same value on all AP's and leave the thermal monitoring interrupt control on all the logical cpu's to the bios. Signed-off-by: Yong Wang Reviewed-by: Suresh Siddha Cc: stable@kernel.org --- arch/x86/kernel/cpu/mcheck/therm_throt.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c b/arch/x86/kernel/cpu/mcheck/therm_throt.c index b3a1dba..1fd42db 100644 --- a/arch/x86/kernel/cpu/mcheck/therm_throt.c +++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c @@ -259,6 +259,7 @@ void intel_init_thermal(struct cpuinfo_x86 *c) unsigned int cpu = smp_processor_id(); int tm2 = 0; u32 l, h; + static u32 lvtthmr; /* Thermal monitoring depends on ACPI and clock modulation*/ if (!cpu_has(c, X86_FEATURE_ACPI) || !cpu_has(c, X86_FEATURE_ACC)) @@ -270,7 +271,24 @@ void intel_init_thermal(struct cpuinfo_x86 *c) * since it might be delivered via SMI already: */ rdmsr(MSR_IA32_MISC_ENABLE, l, h); - h = apic_read(APIC_LVTTHMR); + + /* + * Only read the initial value of thermal LVT entry on BSP. The + * initial value of thermal LVT entries on all APs always reads + * 0x10000 because APs are woken up by BSP issuing INIT-SIPI-SIPI + * sequence to them and LVT registers are reset to 0s except for + * the mask bits which are set to 1s when APs receive INIT IPI. + * Also restore the value that BIOS has programmed on AP based on + * BSP's info we saved since BIOS is always setting the same value + * for all threads/cores + */ + if (cpu == 0) + lvtthmr = apic_read(APIC_LVTTHMR); + else + apic_write(APIC_LVTTHMR, lvtthmr); + + h = lvtthmr; + if ((l & MSR_IA32_MISC_ENABLE_TM1) && (h & APIC_DM_SMI)) { printk(KERN_DEBUG "CPU%d: Thermal monitoring handled by SMI\n", cpu);