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192.168.1.100 / T103 / f818a87834f89b73fe706f85272b12cf466a01c5 / . / src / kernel / linux / v4.14 / arch / x86 / kernel / topology.c
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rjw1f884582022-01-06 17:20:42 +0800[diff] [blame]1/*
2 * Populate sysfs with topology information
3 *
4 * Written by: Matthew Dobson, IBM Corporation
5 * Original Code: Paul Dorwin, IBM Corporation, Patrick Mochel, OSDL
6 *
7 * Copyright (C) 2002, IBM Corp.
8 *
9 * All rights reserved.
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
15 *
16 * This program is distributed in the hope that it will be useful, but
17 * WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
19 * NON INFRINGEMENT. See the GNU General Public License for more
20 * details.
21 *
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software
24 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
25 *
26 * Send feedback to <colpatch@us.ibm.com>
27 */
28#include <linux/nodemask.h>
29#include <linux/export.h>
30#include <linux/mmzone.h>
31#include <linux/init.h>
32#include <linux/smp.h>
33#include <linux/irq.h>
34#include <asm/cpu.h>
35
36static DEFINE_PER_CPU(struct x86_cpu, cpu_devices);
37
38#ifdef CONFIG_HOTPLUG_CPU
39
40#ifdef CONFIG_BOOTPARAM_HOTPLUG_CPU0
41static int cpu0_hotpluggable = 1;
42#else
43static int cpu0_hotpluggable;
44static int __init enable_cpu0_hotplug(char *str)
45{
46 cpu0_hotpluggable = 1;
47 return 1;
48}
49
50__setup("cpu0_hotplug", enable_cpu0_hotplug);
51#endif
52
53#ifdef CONFIG_DEBUG_HOTPLUG_CPU0
54/*
55 * This function offlines a CPU as early as possible and allows userspace to
56 * boot up without the CPU. The CPU can be onlined back by user after boot.
57 *
58 * This is only called for debugging CPU offline/online feature.
59 */
60int _debug_hotplug_cpu(int cpu, int action)
61{
62 struct device *dev = get_cpu_device(cpu);
63 int ret;
64
65 if (!cpu_is_hotpluggable(cpu))
66 return -EINVAL;
67
68 lock_device_hotplug();
69
70 switch (action) {
71 case 0:
72 ret = cpu_down(cpu);
73 if (!ret) {
74 pr_info("CPU %u is now offline\n", cpu);
75 dev->offline = true;
76 kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
77 } else
78 pr_debug("Can't offline CPU%d.\n", cpu);
79 break;
80 case 1:
81 ret = cpu_up(cpu);
82 if (!ret) {
83 dev->offline = false;
84 kobject_uevent(&dev->kobj, KOBJ_ONLINE);
85 } else {
86 pr_debug("Can't online CPU%d.\n", cpu);
87 }
88 break;
89 default:
90 ret = -EINVAL;
91 }
92
93 unlock_device_hotplug();
94
95 return ret;
96}
97
98static int __init debug_hotplug_cpu(void)
99{
100 _debug_hotplug_cpu(0, 0);
101 return 0;
102}
103
104late_initcall_sync(debug_hotplug_cpu);
105#endif /* CONFIG_DEBUG_HOTPLUG_CPU0 */
106
107int arch_register_cpu(int num)
108{
109 struct cpuinfo_x86 *c = &cpu_data(num);
110
111 /*
112 * Currently CPU0 is only hotpluggable on Intel platforms. Other
113 * vendors can add hotplug support later.
114 */
115 if (c->x86_vendor != X86_VENDOR_INTEL)
116 cpu0_hotpluggable = 0;
117
118 /*
119 * Two known BSP/CPU0 dependencies: Resume from suspend/hibernate
120 * depends on BSP. PIC interrupts depend on BSP.
121 *
122 * If the BSP depencies are under control, one can tell kernel to
123 * enable BSP hotplug. This basically adds a control file and
124 * one can attempt to offline BSP.
125 */
126 if (num == 0 && cpu0_hotpluggable) {
127 unsigned int irq;
128 /*
129 * We won't take down the boot processor on i386 if some
130 * interrupts only are able to be serviced by the BSP in PIC.
131 */
132 for_each_active_irq(irq) {
133 if (!IO_APIC_IRQ(irq) && irq_has_action(irq)) {
134 cpu0_hotpluggable = 0;
135 break;
136 }
137 }
138 }
139 if (num || cpu0_hotpluggable)
140 per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
141
142 return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
143}
144EXPORT_SYMBOL(arch_register_cpu);
145
146void arch_unregister_cpu(int num)
147{
148 unregister_cpu(&per_cpu(cpu_devices, num).cpu);
149}
150EXPORT_SYMBOL(arch_unregister_cpu);
151#else /* CONFIG_HOTPLUG_CPU */
152
153static int __init arch_register_cpu(int num)
154{
155 return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
156}
157#endif /* CONFIG_HOTPLUG_CPU */
158
159static int __init topology_init(void)
160{
161 int i;
162
163#ifdef CONFIG_NUMA
164 for_each_online_node(i)
165 register_one_node(i);
166#endif
167
168 for_each_present_cpu(i)
169 arch_register_cpu(i);
170
171 return 0;
172}
173subsys_initcall(topology_init);