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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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af7aa04683
The core device API performs extra housekeeping bits that are missing
from directly calling cpu_up/down().
See commit a6717c01dd ("powerpc/rtas: use device model APIs and
serialization during LPM") for an example description of what might go
wrong.
This also prepares to make cpu_up/down() a private interface of the CPU
subsystem.
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200323135110.30522-10-qais.yousef@arm.com
165 lines
3.9 KiB
C
165 lines
3.9 KiB
C
/*
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* Populate sysfs with topology information
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*
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* Written by: Matthew Dobson, IBM Corporation
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* Original Code: Paul Dorwin, IBM Corporation, Patrick Mochel, OSDL
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*
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* Copyright (C) 2002, IBM Corp.
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*
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
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* NON INFRINGEMENT. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* Send feedback to <colpatch@us.ibm.com>
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*/
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#include <linux/nodemask.h>
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#include <linux/export.h>
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#include <linux/mmzone.h>
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#include <linux/init.h>
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#include <linux/smp.h>
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#include <linux/irq.h>
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#include <asm/cpu.h>
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static DEFINE_PER_CPU(struct x86_cpu, cpu_devices);
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#ifdef CONFIG_HOTPLUG_CPU
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#ifdef CONFIG_BOOTPARAM_HOTPLUG_CPU0
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static int cpu0_hotpluggable = 1;
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#else
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static int cpu0_hotpluggable;
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static int __init enable_cpu0_hotplug(char *str)
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{
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cpu0_hotpluggable = 1;
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return 1;
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}
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__setup("cpu0_hotplug", enable_cpu0_hotplug);
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#endif
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#ifdef CONFIG_DEBUG_HOTPLUG_CPU0
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/*
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* This function offlines a CPU as early as possible and allows userspace to
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* boot up without the CPU. The CPU can be onlined back by user after boot.
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*
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* This is only called for debugging CPU offline/online feature.
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*/
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int _debug_hotplug_cpu(int cpu, int action)
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{
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int ret;
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if (!cpu_is_hotpluggable(cpu))
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return -EINVAL;
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switch (action) {
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case 0:
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ret = remove_cpu(cpu);
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if (!ret)
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pr_info("DEBUG_HOTPLUG_CPU0: CPU %u is now offline\n", cpu);
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else
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pr_debug("Can't offline CPU%d.\n", cpu);
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break;
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case 1:
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ret = add_cpu(cpu);
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if (ret)
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pr_debug("Can't online CPU%d.\n", cpu);
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break;
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default:
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ret = -EINVAL;
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}
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return ret;
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}
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static int __init debug_hotplug_cpu(void)
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{
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_debug_hotplug_cpu(0, 0);
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return 0;
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}
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late_initcall_sync(debug_hotplug_cpu);
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#endif /* CONFIG_DEBUG_HOTPLUG_CPU0 */
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int arch_register_cpu(int num)
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{
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struct cpuinfo_x86 *c = &cpu_data(num);
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/*
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* Currently CPU0 is only hotpluggable on Intel platforms. Other
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* vendors can add hotplug support later.
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* Xen PV guests don't support CPU0 hotplug at all.
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*/
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if (c->x86_vendor != X86_VENDOR_INTEL ||
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boot_cpu_has(X86_FEATURE_XENPV))
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cpu0_hotpluggable = 0;
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/*
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* Two known BSP/CPU0 dependencies: Resume from suspend/hibernate
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* depends on BSP. PIC interrupts depend on BSP.
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*
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* If the BSP depencies are under control, one can tell kernel to
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* enable BSP hotplug. This basically adds a control file and
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* one can attempt to offline BSP.
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*/
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if (num == 0 && cpu0_hotpluggable) {
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unsigned int irq;
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/*
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* We won't take down the boot processor on i386 if some
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* interrupts only are able to be serviced by the BSP in PIC.
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*/
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for_each_active_irq(irq) {
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if (!IO_APIC_IRQ(irq) && irq_has_action(irq)) {
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cpu0_hotpluggable = 0;
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break;
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}
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}
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}
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if (num || cpu0_hotpluggable)
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per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
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return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
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}
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EXPORT_SYMBOL(arch_register_cpu);
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void arch_unregister_cpu(int num)
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{
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unregister_cpu(&per_cpu(cpu_devices, num).cpu);
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}
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EXPORT_SYMBOL(arch_unregister_cpu);
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#else /* CONFIG_HOTPLUG_CPU */
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static int __init arch_register_cpu(int num)
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{
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return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
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}
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#endif /* CONFIG_HOTPLUG_CPU */
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static int __init topology_init(void)
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{
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int i;
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#ifdef CONFIG_NUMA
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for_each_online_node(i)
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register_one_node(i);
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#endif
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for_each_present_cpu(i)
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arch_register_cpu(i);
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return 0;
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}
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subsys_initcall(topology_init);
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