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

#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt

#include <linux/notifier.h>

#include <xen/xen.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[16], state[16];

	sprintf(dir, "cpu/%u", cpu);
	err = xenbus_scanf(XBT_NIL, dir, "availability", "%15s", state);
	if (err != 1) {
		if (!xen_initial_domain())
			pr_err("Unable to read cpu state\n");
		return err;
	}

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

	pr_err("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);
			set_cpu_present(cpu, false);
		}
	}

	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
283c0972 JP	1	#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
283c0972 JP	2
d68d82af AN	3	#include <linux/notifier.h>
d68d82af AN	4
1ccbf534	5	#include <xen/xen.h>
d68d82af AN	6	#include <xen/xenbus.h>
d68d82af AN	7
bb898558	8	#include <asm/xen/hypervisor.h>
d68d82af AN	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
d680eb8b	16	set_cpu_present(cpu, true);
d68d82af AN	17	}
	18
	19	static void disable_hotplug_cpu(int cpu)
	20	{
	21	if (cpu_present(cpu))
	22	arch_unregister_cpu(cpu);
	23
d680eb8b	24	set_cpu_present(cpu, false);
d68d82af AN	25	}
d68d82af AN	26
d745562c	27	static int vcpu_online(unsigned int cpu)
d68d82af AN	28	{
d68d82af AN	29	int err;
e5c702d3	30	char dir[16], state[16];
d68d82af	31
d68d82af	32	sprintf(dir, "cpu/%u", cpu);
e5c702d3	33	err = xenbus_scanf(XBT_NIL, dir, "availability", "%15s", state);
d68d82af	34	if (err != 1) {
5b02aa1e	35	if (!xen_initial_domain())
283c0972	36	pr_err("Unable to read cpu state\n");
d745562c	37	return err;
d68d82af AN	38	}
d68d82af AN	39
d745562c IC	40	if (strcmp(state, "online") == 0)
	41	return 1;
	42	else if (strcmp(state, "offline") == 0)
	43	return 0;
	44
283c0972	45	pr_err("unknown state(%s) on CPU%d\n", state, cpu);
d745562c IC	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:
d68d82af	55	enable_hotplug_cpu(cpu);
d745562c IC	56	break;
d745562c IC	57	case 0:
d68d82af AN	58	(void)cpu_down(cpu);
d68d82af AN	59	disable_hotplug_cpu(cpu);
d745562c IC	60	break;
	61	default:
	62	break;
d68d82af AN	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	{
d745562c	83	int cpu;
d68d82af AN	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
d745562c IC	90	for_each_possible_cpu(cpu) {
	91	if (vcpu_online(cpu) == 0) {
	92	(void)cpu_down(cpu);
d7d3756c	93	set_cpu_present(cpu, false);
d745562c IC	94	}
	95	}
	96
d68d82af AN	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
5c51c637	105	if (!xen_pv_domain())
d68d82af AN	106	return -ENODEV;
	107
	108	register_xenstore_notifier(&xsn_cpu);
	109
	110	return 0;
	111	}
	112
	113	arch_initcall(setup_vcpu_hotplug_event);
	114