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/interrupt.h>
29 #include <linux/nodemask.h>
30 #include <linux/export.h>
31 #include <linux/mmzone.h>
32 #include <linux/init.h>
33 #include <linux/smp.h>
34 #include <linux/irq.h>
35 #include <asm/io_apic.h>
36 #include <asm/cpu.h>
37
38 static DEFINE_PER_CPU(struct x86_cpu, cpu_devices);
39
40 #ifdef CONFIG_HOTPLUG_CPU
41
42 #ifdef CONFIG_BOOTPARAM_HOTPLUG_CPU0
43 static int cpu0_hotpluggable = 1;
44 #else
45 static int cpu0_hotpluggable;
enable_cpu0_hotplug(char * str)46 static int __init enable_cpu0_hotplug(char *str)
47 {
48 cpu0_hotpluggable = 1;
49 return 1;
50 }
51
52 __setup("cpu0_hotplug", enable_cpu0_hotplug);
53 #endif
54
55 #ifdef CONFIG_DEBUG_HOTPLUG_CPU0
56 /*
57 * This function offlines a CPU as early as possible and allows userspace to
58 * boot up without the CPU. The CPU can be onlined back by user after boot.
59 *
60 * This is only called for debugging CPU offline/online feature.
61 */
_debug_hotplug_cpu(int cpu,int action)62 int _debug_hotplug_cpu(int cpu, int action)
63 {
64 int ret;
65
66 if (!cpu_is_hotpluggable(cpu))
67 return -EINVAL;
68
69 switch (action) {
70 case 0:
71 ret = remove_cpu(cpu);
72 if (!ret)
73 pr_info("DEBUG_HOTPLUG_CPU0: CPU %u is now offline\n", cpu);
74 else
75 pr_debug("Can't offline CPU%d.\n", cpu);
76 break;
77 case 1:
78 ret = add_cpu(cpu);
79 if (ret)
80 pr_debug("Can't online CPU%d.\n", cpu);
81
82 break;
83 default:
84 ret = -EINVAL;
85 }
86
87 return ret;
88 }
89
debug_hotplug_cpu(void)90 static int __init debug_hotplug_cpu(void)
91 {
92 _debug_hotplug_cpu(0, 0);
93 return 0;
94 }
95
96 late_initcall_sync(debug_hotplug_cpu);
97 #endif /* CONFIG_DEBUG_HOTPLUG_CPU0 */
98
arch_register_cpu(int num)99 int arch_register_cpu(int num)
100 {
101 struct cpuinfo_x86 *c = &cpu_data(num);
102
103 /*
104 * Currently CPU0 is only hotpluggable on Intel platforms. Other
105 * vendors can add hotplug support later.
106 * Xen PV guests don't support CPU0 hotplug at all.
107 */
108 if (c->x86_vendor != X86_VENDOR_INTEL ||
109 boot_cpu_has(X86_FEATURE_XENPV))
110 cpu0_hotpluggable = 0;
111
112 /*
113 * Two known BSP/CPU0 dependencies: Resume from suspend/hibernate
114 * depends on BSP. PIC interrupts depend on BSP.
115 *
116 * If the BSP dependencies are under control, one can tell kernel to
117 * enable BSP hotplug. This basically adds a control file and
118 * one can attempt to offline BSP.
119 */
120 if (num == 0 && cpu0_hotpluggable) {
121 unsigned int irq;
122 /*
123 * We won't take down the boot processor on i386 if some
124 * interrupts only are able to be serviced by the BSP in PIC.
125 */
126 for_each_active_irq(irq) {
127 if (!IO_APIC_IRQ(irq) && irq_has_action(irq)) {
128 cpu0_hotpluggable = 0;
129 break;
130 }
131 }
132 }
133 if (num || cpu0_hotpluggable)
134 per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
135
136 return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
137 }
138 EXPORT_SYMBOL(arch_register_cpu);
139
arch_unregister_cpu(int num)140 void arch_unregister_cpu(int num)
141 {
142 unregister_cpu(&per_cpu(cpu_devices, num).cpu);
143 }
144 EXPORT_SYMBOL(arch_unregister_cpu);
145 #else /* CONFIG_HOTPLUG_CPU */
146
arch_register_cpu(int num)147 static int __init arch_register_cpu(int num)
148 {
149 return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
150 }
151 #endif /* CONFIG_HOTPLUG_CPU */
152
topology_init(void)153 static int __init topology_init(void)
154 {
155 int i;
156
157 #ifdef CONFIG_NUMA
158 for_each_online_node(i)
159 register_one_node(i);
160 #endif
161
162 for_each_present_cpu(i)
163 arch_register_cpu(i);
164
165 return 0;
166 }
167 subsys_initcall(topology_init);
168