[linux-2.6-block.git] / drivers / xen / cpu_hotplug.c

#include <linux/notifier.h>

#include <xen/xenbus.h>

#include <asm/xen/hypervisor.h>
#include <asm/cpu.h>

static void enable_hotplug_cpu(int cpu)
{
	if (!cpu_present(cpu))
		arch_register_cpu(cpu);

	set_cpu_present(cpu, true);
}

static void disable_hotplug_cpu(int cpu)
{
	if (cpu_present(cpu))
		arch_unregister_cpu(cpu);

	set_cpu_present(cpu, false);
}

static int vcpu_online(unsigned int cpu)
{
	int err;
	char dir[32], state[32];

	sprintf(dir, "cpu/%u", cpu);
	err = xenbus_scanf(XBT_NIL, dir, "availability", "%s", state);
	if (err != 1) {
		printk(KERN_ERR "XENBUS: Unable to read cpu state\n");
		return err;
	}

	if (strcmp(state, "online") == 0)
		return 1;
	else if (strcmp(state, "offline") == 0)
		return 0;

	printk(KERN_ERR "XENBUS: unknown state(%s) on CPU%d\n", state, cpu);
	return -EINVAL;
}
static void vcpu_hotplug(unsigned int cpu)
{
	if (!cpu_possible(cpu))
		return;

	switch (vcpu_online(cpu)) {
	case 1:
		enable_hotplug_cpu(cpu);
		break;
	case 0:
		(void)cpu_down(cpu);
		disable_hotplug_cpu(cpu);
		break;
	default:
		break;
	}
}

static void handle_vcpu_hotplug_event(struct xenbus_watch *watch,
					const char **vec, unsigned int len)
{
	unsigned int cpu;
	char *cpustr;
	const char *node = vec[XS_WATCH_PATH];

	cpustr = strstr(node, "cpu/");
	if (cpustr != NULL) {
		sscanf(cpustr, "cpu/%u", &cpu);
		vcpu_hotplug(cpu);
	}
}

static int setup_cpu_watcher(struct notifier_block *notifier,
			      unsigned long event, void *data)
{
	int cpu;
	static struct xenbus_watch cpu_watch = {
		.node = "cpu",
		.callback = handle_vcpu_hotplug_event};

	(void)register_xenbus_watch(&cpu_watch);

	for_each_possible_cpu(cpu) {
		if (vcpu_online(cpu) == 0) {
			(void)cpu_down(cpu);
			cpu_clear(cpu, cpu_present_map);
		}
	}

	return NOTIFY_DONE;
}

static int __init setup_vcpu_hotplug_event(void)
{
	static struct notifier_block xsn_cpu = {
		.notifier_call = setup_cpu_watcher };

	if (!xen_pv_domain())
		return -ENODEV;

	register_xenstore_notifier(&xsn_cpu);

	return 0;
}

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