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

  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
 11static 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
 19static 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
 27static 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}
 48static 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
 66static 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
 80static 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
100static 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
113arch_initcall(setup_vcpu_hotplug_event);
114