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/io_apic.h>
35 #include <asm/cpu.h>
36
37 static DEFINE_PER_CPU(struct x86_cpu, cpu_devices);
38
39 #ifdef CONFIG_HOTPLUG_CPU
40
41 #ifdef CONFIG_BOOTPARAM_HOTPLUG_CPU0
42 static int cpu0_hotpluggable = 1;
43 #else
44 static int cpu0_hotpluggable;
enable_cpu0_hotplug(char * str)45 static int __init enable_cpu0_hotplug(char *str)
46 {
47 cpu0_hotpluggable = 1;
48 return 1;
49 }
50
51 __setup("cpu0_hotplug", enable_cpu0_hotplug);
52 #endif
53
54 #ifdef CONFIG_DEBUG_HOTPLUG_CPU0
55 /*
56 * This function offlines a CPU as early as possible and allows userspace to
57 * boot up without the CPU. The CPU can be onlined back by user after boot.
58 *
59 * This is only called for debugging CPU offline/online feature.
60 */
_debug_hotplug_cpu(int cpu,int action)61 int _debug_hotplug_cpu(int cpu, int action)
62 {
63 int ret;
64
65 if (!cpu_is_hotpluggable(cpu))
66 return -EINVAL;
67
68 switch (action) {
69 case 0:
70 ret = remove_cpu(cpu);
71 if (!ret)
72 pr_info("DEBUG_HOTPLUG_CPU0: CPU %u is now offline\n", cpu);
73 else
74 pr_debug("Can't offline CPU%d.\n", cpu);
75 break;
76 case 1:
77 ret = add_cpu(cpu);
78 if (ret)
79 pr_debug("Can't online CPU%d.\n", cpu);
80
81 break;
82 default:
83 ret = -EINVAL;
84 }
85
86 return ret;
87 }
88
debug_hotplug_cpu(void)89 static int __init debug_hotplug_cpu(void)
90 {
91 _debug_hotplug_cpu(0, 0);
92 return 0;
93 }
94
95 late_initcall_sync(debug_hotplug_cpu);
96 #endif /* CONFIG_DEBUG_HOTPLUG_CPU0 */
97
arch_register_cpu(int num)98 int arch_register_cpu(int num)
99 {
100 struct cpuinfo_x86 *c = &cpu_data(num);
101
102 /*
103 * Currently CPU0 is only hotpluggable on Intel platforms. Other
104 * vendors can add hotplug support later.
105 * Xen PV guests don't support CPU0 hotplug at all.
106 */
107 if (c->x86_vendor != X86_VENDOR_INTEL ||
108 boot_cpu_has(X86_FEATURE_XENPV))
109 cpu0_hotpluggable = 0;
110
111 /*
112 * Two known BSP/CPU0 dependencies: Resume from suspend/hibernate
113 * depends on BSP. PIC interrupts depend on BSP.
114 *
115 * If the BSP depencies are under control, one can tell kernel to
116 * enable BSP hotplug. This basically adds a control file and
117 * one can attempt to offline BSP.
118 */
119 if (num == 0 && cpu0_hotpluggable) {
120 unsigned int irq;
121 /*
122 * We won't take down the boot processor on i386 if some
123 * interrupts only are able to be serviced by the BSP in PIC.
124 */
125 for_each_active_irq(irq) {
126 if (!IO_APIC_IRQ(irq) && irq_has_action(irq)) {
127 cpu0_hotpluggable = 0;
128 break;
129 }
130 }
131 }
132 if (num || cpu0_hotpluggable)
133 per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
134
135 return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
136 }
137 EXPORT_SYMBOL(arch_register_cpu);
138
arch_unregister_cpu(int num)139 void arch_unregister_cpu(int num)
140 {
141 unregister_cpu(&per_cpu(cpu_devices, num).cpu);
142 }
143 EXPORT_SYMBOL(arch_unregister_cpu);
144 #else /* CONFIG_HOTPLUG_CPU */
145
arch_register_cpu(int num)146 static int __init arch_register_cpu(int num)
147 {
148 return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
149 }
150 #endif /* CONFIG_HOTPLUG_CPU */
151
topology_init(void)152 static int __init topology_init(void)
153 {
154 int i;
155
156 #ifdef CONFIG_NUMA
157 for_each_online_node(i)
158 register_one_node(i);
159 #endif
160
161 for_each_present_cpu(i)
162 arch_register_cpu(i);
163
164 return 0;
165 }
166 subsys_initcall(topology_init);
167
