[linux.git] / drivers / xen / pcpu.c

/******************************************************************************
 * pcpu.c
 * Management physical cpu in dom0, get pcpu info and provide sys interface
 *
 * Copyright (c) 2012 Intel Corporation
 * Author: Liu, Jinsong <[email protected]>
 * Author: Jiang, Yunhong <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/cpu.h>
#include <linux/stat.h>
#include <linux/capability.h>

#include <xen/xen.h>
#include <xen/xenbus.h>
#include <xen/events.h>
#include <xen/interface/platform.h>
#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.h>

#define XEN_PCPU "xen_cpu: "

/*
 * @cpu_id: Xen physical cpu logic number
 * @flags: Xen physical cpu status flag
 * - XEN_PCPU_FLAGS_ONLINE: cpu is online
 * - XEN_PCPU_FLAGS_INVALID: cpu is not present
 */
struct pcpu {
	struct list_head list;
	struct device dev;
	uint32_t cpu_id;
	uint32_t flags;
};

static struct bus_type xen_pcpu_subsys = {
	.name = "xen_cpu",
	.dev_name = "xen_cpu",
};

static DEFINE_MUTEX(xen_pcpu_lock);

static LIST_HEAD(xen_pcpus);

static int xen_pcpu_down(uint32_t cpu_id)
{
	struct xen_platform_op op = {
		.cmd			= XENPF_cpu_offline,
		.interface_version	= XENPF_INTERFACE_VERSION,
		.u.cpu_ol.cpuid		= cpu_id,
	};

	return HYPERVISOR_dom0_op(&op);
}

static int xen_pcpu_up(uint32_t cpu_id)
{
	struct xen_platform_op op = {
		.cmd			= XENPF_cpu_online,
		.interface_version	= XENPF_INTERFACE_VERSION,
		.u.cpu_ol.cpuid		= cpu_id,
	};

	return HYPERVISOR_dom0_op(&op);
}

static ssize_t show_online(struct device *dev,
			   struct device_attribute *attr,
			   char *buf)
{
	struct pcpu *cpu = container_of(dev, struct pcpu, dev);

	return sprintf(buf, "%u\n", !!(cpu->flags & XEN_PCPU_FLAGS_ONLINE));
}

static ssize_t __ref store_online(struct device *dev,
				  struct device_attribute *attr,
				  const char *buf, size_t count)
{
	struct pcpu *pcpu = container_of(dev, struct pcpu, dev);
	unsigned long long val;
	ssize_t ret;

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	if (kstrtoull(buf, 0, &val) < 0)
		return -EINVAL;

	switch (val) {
	case 0:
		ret = xen_pcpu_down(pcpu->cpu_id);
		break;
	case 1:
		ret = xen_pcpu_up(pcpu->cpu_id);
		break;
	default:
		ret = -EINVAL;
	}

	if (ret >= 0)
		ret = count;
	return ret;
}
static DEVICE_ATTR(online, S_IRUGO | S_IWUSR, show_online, store_online);

static bool xen_pcpu_online(uint32_t flags)
{
	return !!(flags & XEN_PCPU_FLAGS_ONLINE);
}

static void pcpu_online_status(struct xenpf_pcpuinfo *info,
			       struct pcpu *pcpu)
{
	if (xen_pcpu_online(info->flags) &&
	   !xen_pcpu_online(pcpu->flags)) {
		/* the pcpu is onlined */
		pcpu->flags |= XEN_PCPU_FLAGS_ONLINE;
		kobject_uevent(&pcpu->dev.kobj, KOBJ_ONLINE);
	} else if (!xen_pcpu_online(info->flags) &&
		    xen_pcpu_online(pcpu->flags)) {
		/* The pcpu is offlined */
		pcpu->flags &= ~XEN_PCPU_FLAGS_ONLINE;
		kobject_uevent(&pcpu->dev.kobj, KOBJ_OFFLINE);
	}
}

static struct pcpu *get_pcpu(uint32_t cpu_id)
{
	struct pcpu *pcpu;

	list_for_each_entry(pcpu, &xen_pcpus, list) {
		if (pcpu->cpu_id == cpu_id)
			return pcpu;
	}

	return NULL;
}

static void pcpu_release(struct device *dev)
{
	struct pcpu *pcpu = container_of(dev, struct pcpu, dev);

	list_del(&pcpu->list);
	kfree(pcpu);
}

static void unregister_and_remove_pcpu(struct pcpu *pcpu)
{
	struct device *dev;

	if (!pcpu)
		return;

	dev = &pcpu->dev;
	if (dev->id)
		device_remove_file(dev, &dev_attr_online);

	/* pcpu remove would be implicitly done */
	device_unregister(dev);
}

static int register_pcpu(struct pcpu *pcpu)
{
	struct device *dev;
	int err = -EINVAL;

	if (!pcpu)
		return err;

	dev = &pcpu->dev;
	dev->bus = &xen_pcpu_subsys;
	dev->id = pcpu->cpu_id;
	dev->release = pcpu_release;

	err = device_register(dev);
	if (err) {
		pcpu_release(dev);
		return err;
	}

	/*
	 * Xen never offline cpu0 due to several restrictions
	 * and assumptions. This basically doesn't add a sys control
	 * to user, one cannot attempt to offline BSP.
	 */
	if (dev->id) {
		err = device_create_file(dev, &dev_attr_online);
		if (err) {
			device_unregister(dev);
			return err;
		}
	}

	return 0;
}

static struct pcpu *create_and_register_pcpu(struct xenpf_pcpuinfo *info)
{
	struct pcpu *pcpu;
	int err;

	if (info->flags & XEN_PCPU_FLAGS_INVALID)
		return ERR_PTR(-ENODEV);

	pcpu = kzalloc(sizeof(struct pcpu), GFP_KERNEL);
	if (!pcpu)
		return ERR_PTR(-ENOMEM);

	INIT_LIST_HEAD(&pcpu->list);
	pcpu->cpu_id = info->xen_cpuid;
	pcpu->flags = info->flags;

	/* Need hold on xen_pcpu_lock before pcpu list manipulations */
	list_add_tail(&pcpu->list, &xen_pcpus);

	err = register_pcpu(pcpu);
	if (err) {
		pr_warning(XEN_PCPU "Failed to register pcpu%u\n",
			   info->xen_cpuid);
		return ERR_PTR(-ENOENT);
	}

	return pcpu;
}

/*
 * Caller should hold the xen_pcpu_lock
 */
static int sync_pcpu(uint32_t cpu, uint32_t *max_cpu)
{
	int ret;
	struct pcpu *pcpu = NULL;
	struct xenpf_pcpuinfo *info;
	struct xen_platform_op op = {
		.cmd                   = XENPF_get_cpuinfo,
		.interface_version     = XENPF_INTERFACE_VERSION,
		.u.pcpu_info.xen_cpuid = cpu,
	};

	ret = HYPERVISOR_dom0_op(&op);
	if (ret)
		return ret;

	info = &op.u.pcpu_info;
	if (max_cpu)
		*max_cpu = info->max_present;

	pcpu = get_pcpu(cpu);

	/*
	 * Only those at cpu present map has its sys interface.
	 */
	if (info->flags & XEN_PCPU_FLAGS_INVALID) {
		unregister_and_remove_pcpu(pcpu);
		return 0;
	}

	if (!pcpu) {
		pcpu = create_and_register_pcpu(info);
		if (IS_ERR_OR_NULL(pcpu))
			return -ENODEV;
	} else
		pcpu_online_status(info, pcpu);

	return 0;
}

/*
 * Sync dom0's pcpu information with xen hypervisor's
 */
static int xen_sync_pcpus(void)
{
	/*
	 * Boot cpu always have cpu_id 0 in xen
	 */
	uint32_t cpu = 0, max_cpu = 0;
	int err = 0;
	struct pcpu *pcpu, *tmp;

	mutex_lock(&xen_pcpu_lock);

	while (!err && (cpu <= max_cpu)) {
		err = sync_pcpu(cpu, &max_cpu);
		cpu++;
	}

	if (err)
		list_for_each_entry_safe(pcpu, tmp, &xen_pcpus, list)
			unregister_and_remove_pcpu(pcpu);

	mutex_unlock(&xen_pcpu_lock);

	return err;
}

static void xen_pcpu_work_fn(struct work_struct *work)
{
	xen_sync_pcpus();
}
static DECLARE_WORK(xen_pcpu_work, xen_pcpu_work_fn);

static irqreturn_t xen_pcpu_interrupt(int irq, void *dev_id)
{
	schedule_work(&xen_pcpu_work);
	return IRQ_HANDLED;
}

/* Sync with Xen hypervisor after cpu hotadded */
void xen_pcpu_hotplug_sync(void)
{
	schedule_work(&xen_pcpu_work);
}
EXPORT_SYMBOL_GPL(xen_pcpu_hotplug_sync);

/*
 * For hypervisor presented cpu, return logic cpu id;
 * For hypervisor non-presented cpu, return -ENODEV.
 */
int xen_pcpu_id(uint32_t acpi_id)
{
	int cpu_id = 0, max_id = 0;
	struct xen_platform_op op;

	op.cmd = XENPF_get_cpuinfo;
	while (cpu_id <= max_id) {
		op.u.pcpu_info.xen_cpuid = cpu_id;
		if (HYPERVISOR_dom0_op(&op)) {
			cpu_id++;
			continue;
		}

		if (acpi_id == op.u.pcpu_info.acpi_id)
			return cpu_id;
		if (op.u.pcpu_info.max_present > max_id)
			max_id = op.u.pcpu_info.max_present;
		cpu_id++;
	}

	return -ENODEV;
}
EXPORT_SYMBOL_GPL(xen_pcpu_id);

static int __init xen_pcpu_init(void)
{
	int irq, ret;

	if (!xen_initial_domain())
		return -ENODEV;

	irq = bind_virq_to_irqhandler(VIRQ_PCPU_STATE, 0,
				      xen_pcpu_interrupt, 0,
				      "xen-pcpu", NULL);
	if (irq < 0) {
		pr_warning(XEN_PCPU "Failed to bind pcpu virq\n");
		return irq;
	}

	ret = subsys_system_register(&xen_pcpu_subsys, NULL);
	if (ret) {
		pr_warning(XEN_PCPU "Failed to register pcpu subsys\n");
		goto err1;
	}

	ret = xen_sync_pcpus();
	if (ret) {
		pr_warning(XEN_PCPU "Failed to sync pcpu info\n");
		goto err2;
	}

	return 0;

err2:
	bus_unregister(&xen_pcpu_subsys);
err1:
	unbind_from_irqhandler(irq, NULL);
	return ret;
}
arch_initcall(xen_pcpu_init);
Commit	Line	Data
f65c9bb3 LJ	1	/******************************************************************************
	2	* pcpu.c
	3	* Management physical cpu in dom0, get pcpu info and provide sys interface
	4	*
	5	* Copyright (c) 2012 Intel Corporation
	6	* Author: Liu, Jinsong <[email protected]>
	7	* Author: Jiang, Yunhong <[email protected]>
	8	*
	9	* This program is free software; you can redistribute it and/or
	10	* modify it under the terms of the GNU General Public License version 2
	11	* as published by the Free Software Foundation; or, when distributed
	12	* separately from the Linux kernel or incorporated into other
	13	* software packages, subject to the following license:
	14	*
	15	* Permission is hereby granted, free of charge, to any person obtaining a copy
	16	* of this source file (the "Software"), to deal in the Software without
	17	* restriction, including without limitation the rights to use, copy, modify,
	18	* merge, publish, distribute, sublicense, and/or sell copies of the Software,
	19	* and to permit persons to whom the Software is furnished to do so, subject to
	20	* the following conditions:
	21	*
	22	* The above copyright notice and this permission notice shall be included in
	23	* all copies or substantial portions of the Software.
	24	*
	25	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	26	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	27	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	28	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	29	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
	30	* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
	31	* IN THE SOFTWARE.
	32	*/
	33
	34	#include <linux/interrupt.h>
	35	#include <linux/spinlock.h>
	36	#include <linux/cpu.h>
	37	#include <linux/stat.h>
	38	#include <linux/capability.h>
	39
	40	#include <xen/xen.h>
	41	#include <xen/xenbus.h>
	42	#include <xen/events.h>
	43	#include <xen/interface/platform.h>
	44	#include <asm/xen/hypervisor.h>
	45	#include <asm/xen/hypercall.h>
	46
	47	#define XEN_PCPU "xen_cpu: "
	48
	49	/*
	50	* @cpu_id: Xen physical cpu logic number
	51	* @flags: Xen physical cpu status flag
	52	* - XEN_PCPU_FLAGS_ONLINE: cpu is online
	53	* - XEN_PCPU_FLAGS_INVALID: cpu is not present
	54	*/
	55	struct pcpu {
	56	struct list_head list;
	57	struct device dev;
	58	uint32_t cpu_id;
	59	uint32_t flags;
	60	};
	61
	62	static struct bus_type xen_pcpu_subsys = {
	63	.name = "xen_cpu",
	64	.dev_name = "xen_cpu",
65	};
66
67	static DEFINE_MUTEX(xen_pcpu_lock);
68
69	static LIST_HEAD(xen_pcpus);
70
71	static int xen_pcpu_down(uint32_t cpu_id)
72	{
73	struct xen_platform_op op = {
74	.cmd = XENPF_cpu_offline,
75	.interface_version = XENPF_INTERFACE_VERSION,
76	.u.cpu_ol.cpuid = cpu_id,
77	};
78
79	return HYPERVISOR_dom0_op(&op);
80	}
81
82	static int xen_pcpu_up(uint32_t cpu_id)
83	{
84	struct xen_platform_op op = {
85	.cmd = XENPF_cpu_online,
86	.interface_version = XENPF_INTERFACE_VERSION,
87	.u.cpu_ol.cpuid = cpu_id,
88	};
89
90	return HYPERVISOR_dom0_op(&op);
91	}
92
93	static ssize_t show_online(struct device *dev,
94	struct device_attribute *attr,
95	char *buf)
96	{
97	struct pcpu *cpu = container_of(dev, struct pcpu, dev);
98
99	return sprintf(buf, "%u\n", !!(cpu->flags & XEN_PCPU_FLAGS_ONLINE));
100	}
101
102	static ssize_t __ref store_online(struct device *dev,
103	struct device_attribute *attr,
104	const char *buf, size_t count)
105	{
106	struct pcpu *pcpu = container_of(dev, struct pcpu, dev);
107	unsigned long long val;
108	ssize_t ret;
109
110	if (!capable(CAP_SYS_ADMIN))
111	return -EPERM;
112
113	if (kstrtoull(buf, 0, &val) < 0)
114	return -EINVAL;
115
116	switch (val) {
117	case 0:
118	ret = xen_pcpu_down(pcpu->cpu_id);
119	break;
120	case 1:
121	ret = xen_pcpu_up(pcpu->cpu_id);
122	break;
123	default:
124	ret = -EINVAL;
125	}
126
127	if (ret >= 0)
128	ret = count;
129	return ret;
130	}
131	static DEVICE_ATTR(online, S_IRUGO \| S_IWUSR, show_online, store_online);
132
133	static bool xen_pcpu_online(uint32_t flags)
134	{
135	return !!(flags & XEN_PCPU_FLAGS_ONLINE);
136	}
137
138	static void pcpu_online_status(struct xenpf_pcpuinfo *info,
139	struct pcpu *pcpu)
140	{
141	if (xen_pcpu_online(info->flags) &&
142	!xen_pcpu_online(pcpu->flags)) {
143	/* the pcpu is onlined */
144	pcpu->flags \|= XEN_PCPU_FLAGS_ONLINE;
145	kobject_uevent(&pcpu->dev.kobj, KOBJ_ONLINE);
146	} else if (!xen_pcpu_online(info->flags) &&
147	xen_pcpu_online(pcpu->flags)) {
148	/* The pcpu is offlined */
149	pcpu->flags &= ~XEN_PCPU_FLAGS_ONLINE;
150	kobject_uevent(&pcpu->dev.kobj, KOBJ_OFFLINE);
151	}
152	}
153
154	static struct pcpu *get_pcpu(uint32_t cpu_id)
155	{
156	struct pcpu *pcpu;
157
158	list_for_each_entry(pcpu, &xen_pcpus, list) {
159	if (pcpu->cpu_id == cpu_id)
160	return pcpu;
161	}
162
163	return NULL;
164	}
165
166	static void pcpu_release(struct device *dev)
167	{
168	struct pcpu *pcpu = container_of(dev, struct pcpu, dev);
169
170	list_del(&pcpu->list);
171	kfree(pcpu);
172	}
173
174	static void unregister_and_remove_pcpu(struct pcpu *pcpu)
175	{
176	struct device *dev;
177
178	if (!pcpu)
179	return;
180
181	dev = &pcpu->dev;
182	if (dev->id)
183	device_remove_file(dev, &dev_attr_online);
184
185	/* pcpu remove would be implicitly done */
186	device_unregister(dev);
187	}
188
189	static int register_pcpu(struct pcpu *pcpu)
190	{
191	struct device *dev;
192	int err = -EINVAL;
193
194	if (!pcpu)
195	return err;
196
197	dev = &pcpu->dev;
198	dev->bus = &xen_pcpu_subsys;
199	dev->id = pcpu->cpu_id;
200	dev->release = pcpu_release;
201
202	err = device_register(dev);
203	if (err) {
204	pcpu_release(dev);
205	return err;
206	}
207
208	/*
209	* Xen never offline cpu0 due to several restrictions
210	* and assumptions. This basically doesn't add a sys control
211	* to user, one cannot attempt to offline BSP.
212	*/
213	if (dev->id) {
214	err = device_create_file(dev, &dev_attr_online);
215	if (err) {
216	device_unregister(dev);
217	return err;
218	}
219	}
220
221	return 0;
222	}
223
224	static struct pcpu create_and_register_pcpu(struct xenpf_pcpuinfo info)
225	{
226	struct pcpu *pcpu;
227	int err;
228
229	if (info->flags & XEN_PCPU_FLAGS_INVALID)
230	return ERR_PTR(-ENODEV);
231
232	pcpu = kzalloc(sizeof(struct pcpu), GFP_KERNEL);
233	if (!pcpu)
234	return ERR_PTR(-ENOMEM);
235
236	INIT_LIST_HEAD(&pcpu->list);
237	pcpu->cpu_id = info->xen_cpuid;
238	pcpu->flags = info->flags;
239
240	/* Need hold on xen_pcpu_lock before pcpu list manipulations */
241	list_add_tail(&pcpu->list, &xen_pcpus);
242
243	err = register_pcpu(pcpu);
244	if (err) {
245	pr_warning(XEN_PCPU "Failed to register pcpu%u\n",
246	info->xen_cpuid);
247	return ERR_PTR(-ENOENT);
248	}
249
250	return pcpu;
251	}
252
253	/*
254	* Caller should hold the xen_pcpu_lock
255	*/
256	static int sync_pcpu(uint32_t cpu, uint32_t *max_cpu)
257	{
258	int ret;
259	struct pcpu *pcpu = NULL;
260	struct xenpf_pcpuinfo *info;
261	struct xen_platform_op op = {
262	.cmd = XENPF_get_cpuinfo,
263	.interface_version = XENPF_INTERFACE_VERSION,
264	.u.pcpu_info.xen_cpuid = cpu,
265	};
266
267	ret = HYPERVISOR_dom0_op(&op);
268	if (ret)
269	return ret;
270
271	info = &op.u.pcpu_info;
272	if (max_cpu)
273	*max_cpu = info->max_present;
274
275	pcpu = get_pcpu(cpu);
276
277	/*
278	* Only those at cpu present map has its sys interface.
279	*/
280	if (info->flags & XEN_PCPU_FLAGS_INVALID) {
4f8c8527	281	unregister_and_remove_pcpu(pcpu);
f65c9bb3 LJ	282	return 0;
	283	}
	284
	285	if (!pcpu) {
	286	pcpu = create_and_register_pcpu(info);
	287	if (IS_ERR_OR_NULL(pcpu))
	288	return -ENODEV;
	289	} else
	290	pcpu_online_status(info, pcpu);
	291
	292	return 0;
	293	}
	294
	295	/*
	296	* Sync dom0's pcpu information with xen hypervisor's
	297	*/
	298	static int xen_sync_pcpus(void)
	299	{
	300	/*
	301	* Boot cpu always have cpu_id 0 in xen
	302	*/
	303	uint32_t cpu = 0, max_cpu = 0;
	304	int err = 0;
	305	struct pcpu pcpu, tmp;
	306
	307	mutex_lock(&xen_pcpu_lock);
	308
	309	while (!err && (cpu <= max_cpu)) {
	310	err = sync_pcpu(cpu, &max_cpu);
	311	cpu++;
	312	}
	313
	314	if (err)
	315	list_for_each_entry_safe(pcpu, tmp, &xen_pcpus, list)
	316	unregister_and_remove_pcpu(pcpu);
	317
	318	mutex_unlock(&xen_pcpu_lock);
	319
	320	return err;
	321	}
	322
	323	static void xen_pcpu_work_fn(struct work_struct *work)
	324	{
	325	xen_sync_pcpus();
	326	}
	327	static DECLARE_WORK(xen_pcpu_work, xen_pcpu_work_fn);
	328
	329	static irqreturn_t xen_pcpu_interrupt(int irq, void *dev_id)
	330	{
	331	schedule_work(&xen_pcpu_work);
	332	return IRQ_HANDLED;
	333	}
	334
39adc483 LJ	335	/* Sync with Xen hypervisor after cpu hotadded */
	336	void xen_pcpu_hotplug_sync(void)
	337	{
	338	schedule_work(&xen_pcpu_work);
	339	}
	340	EXPORT_SYMBOL_GPL(xen_pcpu_hotplug_sync);
	341
	342	/*
	343	* For hypervisor presented cpu, return logic cpu id;
	344	* For hypervisor non-presented cpu, return -ENODEV.
	345	*/
	346	int xen_pcpu_id(uint32_t acpi_id)
	347	{
	348	int cpu_id = 0, max_id = 0;
	349	struct xen_platform_op op;
	350
	351	op.cmd = XENPF_get_cpuinfo;
	352	while (cpu_id <= max_id) {
	353	op.u.pcpu_info.xen_cpuid = cpu_id;
	354	if (HYPERVISOR_dom0_op(&op)) {
	355	cpu_id++;
	356	continue;
	357	}
	358
	359	if (acpi_id == op.u.pcpu_info.acpi_id)
	360	return cpu_id;
	361	if (op.u.pcpu_info.max_present > max_id)
	362	max_id = op.u.pcpu_info.max_present;
	363	cpu_id++;
	364	}
	365
	366	return -ENODEV;
	367	}
	368	EXPORT_SYMBOL_GPL(xen_pcpu_id);
	369
f65c9bb3 LJ	370	static int __init xen_pcpu_init(void)
	371	{
	372	int irq, ret;
	373
	374	if (!xen_initial_domain())
	375	return -ENODEV;
	376
	377	irq = bind_virq_to_irqhandler(VIRQ_PCPU_STATE, 0,
	378	xen_pcpu_interrupt, 0,
	379	"xen-pcpu", NULL);
	380	if (irq < 0) {
	381	pr_warning(XEN_PCPU "Failed to bind pcpu virq\n");
	382	return irq;
	383	}
	384
	385	ret = subsys_system_register(&xen_pcpu_subsys, NULL);
	386	if (ret) {
	387	pr_warning(XEN_PCPU "Failed to register pcpu subsys\n");
	388	goto err1;
	389	}
	390
	391	ret = xen_sync_pcpus();
	392	if (ret) {
	393	pr_warning(XEN_PCPU "Failed to sync pcpu info\n");
	394	goto err2;
	395	}
	396
	397	return 0;
	398
	399	err2:
	400	bus_unregister(&xen_pcpu_subsys);
	401	err1:
	402	unbind_from_irqhandler(irq, NULL);
	403	return ret;
	404	}
	405	arch_initcall(xen_pcpu_init);