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

  1#include <linux/notifier.h>
  2
  3#include <xen/xen.h>
  4#include <xen/xenbus.h>
  5
  6#include <asm/xen/hypervisor.h>
  7#include <asm/cpu.h>
  8
  9static void enable_hotplug_cpu(int cpu)
 10{
 11	if (!cpu_present(cpu))
 12		arch_register_cpu(cpu);
 13
 14	set_cpu_present(cpu, true);
 15}
 16
 17static void disable_hotplug_cpu(int cpu)
 18{
 19	if (cpu_present(cpu))
 20		arch_unregister_cpu(cpu);
 21
 22	set_cpu_present(cpu, false);
 23}
 24
 25static int vcpu_online(unsigned int cpu)
 26{
 27	int err;
 28	char dir[32], state[32];
 29
 30	sprintf(dir, "cpu/%u", cpu);
 31	err = xenbus_scanf(XBT_NIL, dir, "availability", "%s", state);
 32	if (err != 1) {
 33		if (!xen_initial_domain())
 34			printk(KERN_ERR "XENBUS: Unable to read cpu state\n");
 35		return err;
 36	}
 37
 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}
 46static void vcpu_hotplug(unsigned int cpu)
 47{
 48	if (!cpu_possible(cpu))
 49		return;
 50
 51	switch (vcpu_online(cpu)) {
 52	case 1:
 53		enable_hotplug_cpu(cpu);
 54		break;
 55	case 0:
 56		(void)cpu_down(cpu);
 57		disable_hotplug_cpu(cpu);
 58		break;
 59	default:
 60		break;
 61	}
 62}
 63
 64static 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
 78static int setup_cpu_watcher(struct notifier_block *notifier,
 79			      unsigned long event, void *data)
 80{
 81	int cpu;
 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
 88	for_each_possible_cpu(cpu) {
 89		if (vcpu_online(cpu) == 0) {
 90			(void)cpu_down(cpu);
 91			set_cpu_present(cpu, false);
 92		}
 93	}
 94
 95	return NOTIFY_DONE;
 96}
 97
 98static int __init setup_vcpu_hotplug_event(void)
 99{
100	static struct notifier_block xsn_cpu = {
101		.notifier_call = setup_cpu_watcher };
102
103	if (!xen_pv_domain())
104		return -ENODEV;
105
106	register_xenstore_notifier(&xsn_cpu);
107
108	return 0;
109}
110
111arch_initcall(setup_vcpu_hotplug_event);
112