Merge branch 'master' into for-next
[platform/adaptation/renesas_rcar/renesas_kernel.git] / drivers / xen / cpu_hotplug.c
1 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
2
3 #include <linux/notifier.h>
4
5 #include <xen/xen.h>
6 #include <xen/xenbus.h>
7
8 #include <asm/xen/hypervisor.h>
9 #include <asm/cpu.h>
10
11 static void enable_hotplug_cpu(int cpu)
12 {
13         if (!cpu_present(cpu))
14                 arch_register_cpu(cpu);
15
16         set_cpu_present(cpu, true);
17 }
18
19 static void disable_hotplug_cpu(int cpu)
20 {
21         if (cpu_present(cpu))
22                 arch_unregister_cpu(cpu);
23
24         set_cpu_present(cpu, false);
25 }
26
27 static int vcpu_online(unsigned int cpu)
28 {
29         int err;
30         char dir[16], state[16];
31
32         sprintf(dir, "cpu/%u", cpu);
33         err = xenbus_scanf(XBT_NIL, dir, "availability", "%15s", state);
34         if (err != 1) {
35                 if (!xen_initial_domain())
36                         pr_err("Unable to read cpu state\n");
37                 return err;
38         }
39
40         if (strcmp(state, "online") == 0)
41                 return 1;
42         else if (strcmp(state, "offline") == 0)
43                 return 0;
44
45         pr_err("unknown state(%s) on CPU%d\n", state, cpu);
46         return -EINVAL;
47 }
48 static void vcpu_hotplug(unsigned int cpu)
49 {
50         if (!cpu_possible(cpu))
51                 return;
52
53         switch (vcpu_online(cpu)) {
54         case 1:
55                 enable_hotplug_cpu(cpu);
56                 break;
57         case 0:
58                 (void)cpu_down(cpu);
59                 disable_hotplug_cpu(cpu);
60                 break;
61         default:
62                 break;
63         }
64 }
65
66 static void handle_vcpu_hotplug_event(struct xenbus_watch *watch,
67                                         const char **vec, unsigned int len)
68 {
69         unsigned int cpu;
70         char *cpustr;
71         const char *node = vec[XS_WATCH_PATH];
72
73         cpustr = strstr(node, "cpu/");
74         if (cpustr != NULL) {
75                 sscanf(cpustr, "cpu/%u", &cpu);
76                 vcpu_hotplug(cpu);
77         }
78 }
79
80 static int setup_cpu_watcher(struct notifier_block *notifier,
81                               unsigned long event, void *data)
82 {
83         int cpu;
84         static struct xenbus_watch cpu_watch = {
85                 .node = "cpu",
86                 .callback = handle_vcpu_hotplug_event};
87
88         (void)register_xenbus_watch(&cpu_watch);
89
90         for_each_possible_cpu(cpu) {
91                 if (vcpu_online(cpu) == 0) {
92                         (void)cpu_down(cpu);
93                         set_cpu_present(cpu, false);
94                 }
95         }
96
97         return NOTIFY_DONE;
98 }
99
100 static int __init setup_vcpu_hotplug_event(void)
101 {
102         static struct notifier_block xsn_cpu = {
103                 .notifier_call = setup_cpu_watcher };
104
105         if (!xen_pv_domain())
106                 return -ENODEV;
107
108         register_xenstore_notifier(&xsn_cpu);
109
110         return 0;
111 }
112
113 arch_initcall(setup_vcpu_hotplug_event);
114