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d68d82af AN |
1 | #include <linux/notifier.h> |
2 | ||
1ccbf534 | 3 | #include <xen/xen.h> |
d68d82af AN |
4 | #include <xen/xenbus.h> |
5 | ||
bb898558 | 6 | #include <asm/xen/hypervisor.h> |
d68d82af AN |
7 | #include <asm/cpu.h> |
8 | ||
9 | static void enable_hotplug_cpu(int cpu) | |
10 | { | |
11 | if (!cpu_present(cpu)) | |
12 | arch_register_cpu(cpu); | |
13 | ||
d680eb8b | 14 | set_cpu_present(cpu, true); |
d68d82af AN |
15 | } |
16 | ||
17 | static void disable_hotplug_cpu(int cpu) | |
18 | { | |
19 | if (cpu_present(cpu)) | |
20 | arch_unregister_cpu(cpu); | |
21 | ||
d680eb8b | 22 | set_cpu_present(cpu, false); |
d68d82af AN |
23 | } |
24 | ||
d745562c | 25 | static int vcpu_online(unsigned int cpu) |
d68d82af AN |
26 | { |
27 | int err; | |
28 | char dir[32], state[32]; | |
29 | ||
d68d82af AN |
30 | sprintf(dir, "cpu/%u", cpu); |
31 | err = xenbus_scanf(XBT_NIL, dir, "availability", "%s", state); | |
32 | if (err != 1) { | |
5b02aa1e KRW |
33 | if (!xen_initial_domain()) |
34 | printk(KERN_ERR "XENBUS: Unable to read cpu state\n"); | |
d745562c | 35 | return err; |
d68d82af AN |
36 | } |
37 | ||
d745562c IC |
38 | if (strcmp(state, "online") == 0) |
39 | return 1; | |
40 | else if (strcmp(state, "offline") == 0) | |
41 | return 0; | |
42 | ||
43 | printk(KERN_ERR "XENBUS: unknown state(%s) on CPU%d\n", state, cpu); | |
44 | return -EINVAL; | |
45 | } | |
46 | static void vcpu_hotplug(unsigned int cpu) | |
47 | { | |
48 | if (!cpu_possible(cpu)) | |
49 | return; | |
50 | ||
51 | switch (vcpu_online(cpu)) { | |
52 | case 1: | |
d68d82af | 53 | enable_hotplug_cpu(cpu); |
d745562c IC |
54 | break; |
55 | case 0: | |
d68d82af AN |
56 | (void)cpu_down(cpu); |
57 | disable_hotplug_cpu(cpu); | |
d745562c IC |
58 | break; |
59 | default: | |
60 | break; | |
d68d82af AN |
61 | } |
62 | } | |
63 | ||
64 | static void handle_vcpu_hotplug_event(struct xenbus_watch *watch, | |
65 | const char **vec, unsigned int len) | |
66 | { | |
67 | unsigned int cpu; | |
68 | char *cpustr; | |
69 | const char *node = vec[XS_WATCH_PATH]; | |
70 | ||
71 | cpustr = strstr(node, "cpu/"); | |
72 | if (cpustr != NULL) { | |
73 | sscanf(cpustr, "cpu/%u", &cpu); | |
74 | vcpu_hotplug(cpu); | |
75 | } | |
76 | } | |
77 | ||
78 | static int setup_cpu_watcher(struct notifier_block *notifier, | |
79 | unsigned long event, void *data) | |
80 | { | |
d745562c | 81 | int cpu; |
d68d82af AN |
82 | static struct xenbus_watch cpu_watch = { |
83 | .node = "cpu", | |
84 | .callback = handle_vcpu_hotplug_event}; | |
85 | ||
86 | (void)register_xenbus_watch(&cpu_watch); | |
87 | ||
d745562c IC |
88 | for_each_possible_cpu(cpu) { |
89 | if (vcpu_online(cpu) == 0) { | |
90 | (void)cpu_down(cpu); | |
d7d3756c | 91 | set_cpu_present(cpu, false); |
d745562c IC |
92 | } |
93 | } | |
94 | ||
d68d82af AN |
95 | return NOTIFY_DONE; |
96 | } | |
97 | ||
98 | static int __init setup_vcpu_hotplug_event(void) | |
99 | { | |
100 | static struct notifier_block xsn_cpu = { | |
101 | .notifier_call = setup_cpu_watcher }; | |
102 | ||
5c51c637 | 103 | if (!xen_pv_domain()) |
d68d82af AN |
104 | return -ENODEV; |
105 | ||
106 | register_xenstore_notifier(&xsn_cpu); | |
107 | ||
108 | return 0; | |
109 | } | |
110 | ||
111 | arch_initcall(setup_vcpu_hotplug_event); | |
112 |