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// SPDX-License-Identifier: GPL-2.0
  2#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
  3
  4#include <linux/notifier.h>
  5
  6#include <xen/xen.h>
  7#include <xen/xenbus.h>
  8
  9#include <asm/xen/hypervisor.h>
 10#include <asm/cpu.h>
 11
 12static void enable_hotplug_cpu(int cpu)
 13{
 14	if (!cpu_present(cpu))
 15		xen_arch_register_cpu(cpu);
 16
 17	set_cpu_present(cpu, true);
 18}
 19
 20static void disable_hotplug_cpu(int cpu)
 21{
 22	if (!cpu_is_hotpluggable(cpu))
 23		return;
 24	lock_device_hotplug();
 25	if (cpu_online(cpu))
 26		device_offline(get_cpu_device(cpu));
 27	if (!cpu_online(cpu) && cpu_present(cpu)) {
 28		xen_arch_unregister_cpu(cpu);
 29		set_cpu_present(cpu, false);
 30	}
 31	unlock_device_hotplug();
 32}
 33
 34static int vcpu_online(unsigned int cpu)
 35{
 36	int err;
 37	char dir[16], state[16];
 38
 39	sprintf(dir, "cpu/%u", cpu);
 40	err = xenbus_scanf(XBT_NIL, dir, "availability", "%15s", state);
 41	if (err != 1) {
 42		if (!xen_initial_domain())
 43			pr_err("Unable to read cpu state\n");
 44		return err;
 45	}
 46
 47	if (strcmp(state, "online") == 0)
 48		return 1;
 49	else if (strcmp(state, "offline") == 0)
 50		return 0;
 51
 52	pr_err("unknown state(%s) on CPU%d\n", state, cpu);
 53	return -EINVAL;
 54}
 55static void vcpu_hotplug(unsigned int cpu)
 56{
 57	if (cpu >= nr_cpu_ids || !cpu_possible(cpu))
 58		return;
 59
 60	switch (vcpu_online(cpu)) {
 61	case 1:
 62		enable_hotplug_cpu(cpu);
 63		break;
 64	case 0:
 
 65		disable_hotplug_cpu(cpu);
 66		break;
 67	default:
 68		break;
 69	}
 70}
 71
 72static void handle_vcpu_hotplug_event(struct xenbus_watch *watch,
 73				      const char *path, const char *token)
 74{
 75	unsigned int cpu;
 76	char *cpustr;
 
 77
 78	cpustr = strstr(path, "cpu/");
 79	if (cpustr != NULL) {
 80		sscanf(cpustr, "cpu/%u", &cpu);
 81		vcpu_hotplug(cpu);
 82	}
 83}
 84
 85static int setup_cpu_watcher(struct notifier_block *notifier,
 86			      unsigned long event, void *data)
 87{
 88	int cpu;
 89	static struct xenbus_watch cpu_watch = {
 90		.node = "cpu",
 91		.callback = handle_vcpu_hotplug_event};
 92
 93	(void)register_xenbus_watch(&cpu_watch);
 94
 95	for_each_possible_cpu(cpu) {
 96		if (vcpu_online(cpu) == 0)
 97			disable_hotplug_cpu(cpu);
 
 
 98	}
 99
100	return NOTIFY_DONE;
101}
102
103static int __init setup_vcpu_hotplug_event(void)
104{
105	static struct notifier_block xsn_cpu = {
106		.notifier_call = setup_cpu_watcher };
107
108#ifdef CONFIG_X86
109	if (!xen_pv_domain() && !xen_pvh_domain())
110#else
111	if (!xen_domain())
112#endif
113		return -ENODEV;
114
115	register_xenstore_notifier(&xsn_cpu);
116
117	return 0;
118}
119
120late_initcall(setup_vcpu_hotplug_event);
121