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

// SPDX-License-Identifier: GPL-2.0
#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))
		xen_arch_register_cpu(cpu);

	set_cpu_present(cpu, true);
}

static void disable_hotplug_cpu(int cpu)
{
	if (!cpu_is_hotpluggable(cpu))
		return;
	lock_device_hotplug();
	if (cpu_online(cpu))
		device_offline(get_cpu_device(cpu));
	if (!cpu_online(cpu) && cpu_present(cpu)) {
		xen_arch_unregister_cpu(cpu);
		set_cpu_present(cpu, false);
	}
	unlock_device_hotplug();
}

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 >= nr_cpu_ids || !cpu_possible(cpu))
		return;

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

static void handle_vcpu_hotplug_event(struct xenbus_watch *watch,
				      const char *path, const char *token)
{
	unsigned int cpu;
	char *cpustr;

	cpustr = strstr(path, "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)
			disable_hotplug_cpu(cpu);
	}

	return NOTIFY_DONE;
}

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

#ifdef CONFIG_X86
	if (!xen_pv_domain() && !xen_pvh_domain())
#else
	if (!xen_domain())
#endif
		return -ENODEV;

	register_xenstore_notifier(&xsn_cpu);

	return 0;
}

late_initcall(setup_vcpu_hotplug_event);
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
283c0972 JP	2	#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
283c0972 JP	3
d68d82af AN	4	#include <linux/notifier.h>
d68d82af AN	5
1ccbf534	6	#include <xen/xen.h>
d68d82af AN	7	#include <xen/xenbus.h>
d68d82af AN	8
bb898558	9	#include <asm/xen/hypervisor.h>
d68d82af AN	10	#include <asm/cpu.h>
	11
	12	static void enable_hotplug_cpu(int cpu)
	13	{
	14	if (!cpu_present(cpu))
a314e3eb	15	xen_arch_register_cpu(cpu);
d68d82af	16
d680eb8b	17	set_cpu_present(cpu, true);
d68d82af AN	18	}
	19
	20	static void disable_hotplug_cpu(int cpu)
	21	{
3366cdb6 OH	22	if (!cpu_is_hotpluggable(cpu))
	23	return;
	24	lock_device_hotplug();
	25	if (cpu_online(cpu))
1c7a6213	26	device_offline(get_cpu_device(cpu));
3366cdb6	27	if (!cpu_online(cpu) && cpu_present(cpu)) {
a314e3eb	28	xen_arch_unregister_cpu(cpu);
3366cdb6 OH	29	set_cpu_present(cpu, false);
	30	}
	31	unlock_device_hotplug();
d68d82af AN	32	}
d68d82af AN	33
d745562c	34	static int vcpu_online(unsigned int cpu)
d68d82af AN	35	{
d68d82af AN	36	int err;
e5c702d3	37	char dir[16], state[16];
d68d82af	38
d68d82af	39	sprintf(dir, "cpu/%u", cpu);
e5c702d3	40	err = xenbus_scanf(XBT_NIL, dir, "availability", "%15s", state);
d68d82af	41	if (err != 1) {
5b02aa1e	42	if (!xen_initial_domain())
283c0972	43	pr_err("Unable to read cpu state\n");
d745562c	44	return err;
d68d82af AN	45	}
d68d82af AN	46
d745562c IC	47	if (strcmp(state, "online") == 0)
	48	return 1;
	49	else if (strcmp(state, "offline") == 0)
	50	return 0;
	51
283c0972	52	pr_err("unknown state(%s) on CPU%d\n", state, cpu);
d745562c IC	53	return -EINVAL;
	54	}
	55	static void vcpu_hotplug(unsigned int cpu)
	56	{
20167609	57	if (cpu >= nr_cpu_ids \|\| !cpu_possible(cpu))
d745562c IC	58	return;
	59
	60	switch (vcpu_online(cpu)) {
	61	case 1:
d68d82af	62	enable_hotplug_cpu(cpu);
d745562c IC	63	break;
d745562c IC	64	case 0:
d68d82af	65	disable_hotplug_cpu(cpu);
d745562c IC	66	break;
	67	default:
	68	break;
d68d82af AN	69	}
	70	}
	71
	72	static void handle_vcpu_hotplug_event(struct xenbus_watch *watch,
5584ea25	73	const char path, const char token)
d68d82af AN	74	{
	75	unsigned int cpu;
	76	char *cpustr;
d68d82af	77
5584ea25	78	cpustr = strstr(path, "cpu/");
d68d82af AN	79	if (cpustr != NULL) {
	80	sscanf(cpustr, "cpu/%u", &cpu);
	81	vcpu_hotplug(cpu);
	82	}
	83	}
	84
	85	static int setup_cpu_watcher(struct notifier_block *notifier,
	86	unsigned long event, void *data)
	87	{
d745562c	88	int cpu;
d68d82af AN	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
d745562c	95	for_each_possible_cpu(cpu) {
c54b071c BO	96	if (vcpu_online(cpu) == 0)
c54b071c BO	97	disable_hotplug_cpu(cpu);
d745562c IC	98	}
d745562c IC	99
d68d82af AN	100	return NOTIFY_DONE;
	101	}
	102
	103	static int __init setup_vcpu_hotplug_event(void)
	104	{
	105	static struct notifier_block xsn_cpu = {
	106	.notifier_call = setup_cpu_watcher };
	107
a314e3eb	108	#ifdef CONFIG_X86
2a7197f0	109	if (!xen_pv_domain() && !xen_pvh_domain())
a314e3eb SS	110	#else
	111	if (!xen_domain())
	112	#endif
d68d82af AN	113	return -ENODEV;
	114
	115	register_xenstore_notifier(&xsn_cpu);
	116
	117	return 0;
	118	}
	119
c54b071c	120	late_initcall(setup_vcpu_hotplug_event);
d68d82af	121