From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933209Ab2KNWo1 (ORCPT ); Wed, 14 Nov 2012 17:44:27 -0500 Received: from terminus.zytor.com ([198.137.202.10]:45491 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932997Ab2KNWo0 (ORCPT ); Wed, 14 Nov 2012 17:44:26 -0500 Date: Wed, 14 Nov 2012 13:23:41 -0800 From: tip-bot for Fenghua Yu Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, fenghua.yu@intel.com, tglx@linutronix.de, hpa@linux.intel.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, fenghua.yu@intel.com, tglx@linutronix.de, hpa@linux.intel.com In-Reply-To: <1352835171-3958-4-git-send-email-fenghua.yu@intel.com> References: <1352835171-3958-4-git-send-email-fenghua.yu@intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/bsp-hotplug] x86, topology: Don' t offline CPU0 if any PIC irq can not be migrated out of it Git-Commit-ID: 4d25031a81d3cd32edc00de6596db76cc4010685 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (terminus.zytor.com [127.0.0.1]); Wed, 14 Nov 2012 14:44:19 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 4d25031a81d3cd32edc00de6596db76cc4010685 Gitweb: http://git.kernel.org/tip/4d25031a81d3cd32edc00de6596db76cc4010685 Author: Fenghua Yu AuthorDate: Tue, 13 Nov 2012 11:32:40 -0800 Committer: H. Peter Anvin CommitDate: Wed, 14 Nov 2012 09:39:47 -0800 x86, topology: Don't offline CPU0 if any PIC irq can not be migrated out of it If CONFIG_BOOTPARAM_HOTPLUG_CPU is turned on, CPU0 hotplug feature is enabled by default. If CONFIG_BOOTPARAM_HOTPLUG_CPU is not turned on, CPU0 hotplug feature is not enabled by default. The kernel parameter cpu0_hotplug can enable CPU0 hotplug feature at boot. Currently the feature is supported on Intel platforms only. Signed-off-by: Fenghua Yu Link: http://lkml.kernel.org/r/1352835171-3958-4-git-send-email-fenghua.yu@intel.com Signed-off-by: H. Peter Anvin --- arch/x86/kernel/topology.c | 50 +++++++++++++++++++++++++++++++++++++++------- 1 file changed, 43 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c index 76ee977..0e7b4a7 100644 --- a/arch/x86/kernel/topology.c +++ b/arch/x86/kernel/topology.c @@ -30,23 +30,59 @@ #include #include #include +#include #include static DEFINE_PER_CPU(struct x86_cpu, cpu_devices); #ifdef CONFIG_HOTPLUG_CPU + +#ifdef CONFIG_BOOTPARAM_HOTPLUG_CPU0 +static int cpu0_hotpluggable = 1; +#else +static int cpu0_hotpluggable; +static int __init enable_cpu0_hotplug(char *str) +{ + cpu0_hotpluggable = 1; + return 1; +} + +__setup("cpu0_hotplug", enable_cpu0_hotplug); +#endif + int __ref arch_register_cpu(int num) { + struct cpuinfo_x86 *c = &cpu_data(num); + + /* + * Currently CPU0 is only hotpluggable on Intel platforms. Other + * vendors can add hotplug support later. + */ + if (c->x86_vendor != X86_VENDOR_INTEL) + cpu0_hotpluggable = 0; + /* - * CPU0 cannot be offlined due to several - * restrictions and assumptions in kernel. This basically - * doesn't add a control file, one cannot attempt to offline - * BSP. + * Two known BSP/CPU0 dependencies: Resume from suspend/hibernate + * depends on BSP. PIC interrupts depend on BSP. * - * Also certain PCI quirks require not to enable hotplug control - * for all CPU's. + * If the BSP depencies are under control, one can tell kernel to + * enable BSP hotplug. This basically adds a control file and + * one can attempt to offline BSP. */ - if (num) + if (num == 0 && cpu0_hotpluggable) { + unsigned int irq; + /* + * We won't take down the boot processor on i386 if some + * interrupts only are able to be serviced by the BSP in PIC. + */ + for_each_active_irq(irq) { + if (!IO_APIC_IRQ(irq) && irq_has_action(irq)) { + cpu0_hotpluggable = 0; + break; + } + } + } + if (num || cpu0_hotpluggable) per_cpu(cpu_devices, num).cpu.hotpluggable = 1; return register_cpu(&per_cpu(cpu_devices, num).cpu, num);