[mirror_ubuntu-artful-kernel.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 <jinsong.liu@intel.com>
 * Author: Jiang, Yunhong <yunhong.jiang@intel.com>
 *
 * 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.
 */

#define pr_fmt(fmt) "xen_cpu: " fmt

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


/*
 * @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_platform_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_platform_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 struct attribute *pcpu_dev_attrs[] = {
	&dev_attr_online.attr,
	NULL
};

static umode_t pcpu_dev_is_visible(struct kobject *kobj,
				   struct attribute *attr, int idx)
{
	struct device *dev = kobj_to_dev(kobj);
	/*
	 * 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.
	 */
	return dev->id ? attr->mode : 0;
}

static const struct attribute_group pcpu_dev_group = {
	.attrs = pcpu_dev_attrs,
	.is_visible = pcpu_dev_is_visible,
};

static const struct attribute_group *pcpu_dev_groups[] = {
	&pcpu_dev_group,
	NULL
};

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;
	/* 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;
	dev->groups = pcpu_dev_groups;

	err = device_register(dev);
	if (err) {
		pcpu_release(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_warn("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_platform_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_platform_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_warn("Failed to bind pcpu virq\n");
		return irq;
	}

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

	ret = xen_sync_pcpus();
	if (ret) {
		pr_warn("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 <jinsong.liu@intel.com>
	7	* Author: Jiang, Yunhong <yunhong.jiang@intel.com>
	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
283c0972 JP	34	#define pr_fmt(fmt) "xen_cpu: " fmt
283c0972 JP	35
f65c9bb3 LJ	36	#include <linux/interrupt.h>
	37	#include <linux/spinlock.h>
	38	#include <linux/cpu.h>
	39	#include <linux/stat.h>
	40	#include <linux/capability.h>
	41
	42	#include <xen/xen.h>
6cb606f1	43	#include <xen/acpi.h>
f65c9bb3 LJ	44	#include <xen/xenbus.h>
	45	#include <xen/events.h>
	46	#include <xen/interface/platform.h>
	47	#include <asm/xen/hypervisor.h>
	48	#include <asm/xen/hypercall.h>
	49
f65c9bb3 LJ	50
	51	/*
	52	* @cpu_id: Xen physical cpu logic number
	53	* @flags: Xen physical cpu status flag
	54	* - XEN_PCPU_FLAGS_ONLINE: cpu is online
	55	* - XEN_PCPU_FLAGS_INVALID: cpu is not present
	56	*/
	57	struct pcpu {
	58	struct list_head list;
	59	struct device dev;
	60	uint32_t cpu_id;
	61	uint32_t flags;
	62	};
	63
	64	static struct bus_type xen_pcpu_subsys = {
	65	.name = "xen_cpu",
	66	.dev_name = "xen_cpu",
	67	};
	68
	69	static DEFINE_MUTEX(xen_pcpu_lock);
	70
	71	static LIST_HEAD(xen_pcpus);
	72
	73	static int xen_pcpu_down(uint32_t cpu_id)
	74	{
	75	struct xen_platform_op op = {
	76	.cmd = XENPF_cpu_offline,
	77	.interface_version = XENPF_INTERFACE_VERSION,
	78	.u.cpu_ol.cpuid = cpu_id,
	79	};
	80
cfafae94	81	return HYPERVISOR_platform_op(&op);
f65c9bb3 LJ	82	}
	83
	84	static int xen_pcpu_up(uint32_t cpu_id)
	85	{
	86	struct xen_platform_op op = {
	87	.cmd = XENPF_cpu_online,
	88	.interface_version = XENPF_INTERFACE_VERSION,
	89	.u.cpu_ol.cpuid = cpu_id,
	90	};
	91
cfafae94	92	return HYPERVISOR_platform_op(&op);
f65c9bb3 LJ	93	}
	94
	95	static ssize_t show_online(struct device *dev,
	96	struct device_attribute *attr,
	97	char *buf)
	98	{
	99	struct pcpu *cpu = container_of(dev, struct pcpu, dev);
	100
	101	return sprintf(buf, "%u\n", !!(cpu->flags & XEN_PCPU_FLAGS_ONLINE));
	102	}
	103
	104	static ssize_t __ref store_online(struct device *dev,
	105	struct device_attribute *attr,
	106	const char *buf, size_t count)
	107	{
	108	struct pcpu *pcpu = container_of(dev, struct pcpu, dev);
	109	unsigned long long val;
	110	ssize_t ret;
	111
	112	if (!capable(CAP_SYS_ADMIN))
	113	return -EPERM;
	114
	115	if (kstrtoull(buf, 0, &val) < 0)
	116	return -EINVAL;
	117
	118	switch (val) {
	119	case 0:
	120	ret = xen_pcpu_down(pcpu->cpu_id);
	121	break;
	122	case 1:
	123	ret = xen_pcpu_up(pcpu->cpu_id);
	124	break;
	125	default:
	126	ret = -EINVAL;
	127	}
	128
	129	if (ret >= 0)
	130	ret = count;
	131	return ret;
	132	}
	133	static DEVICE_ATTR(online, S_IRUGO \| S_IWUSR, show_online, store_online);
	134
4644e5ab TI	135	static struct attribute *pcpu_dev_attrs[] = {
	136	&dev_attr_online.attr,
	137	NULL
	138	};
	139
	140	static umode_t pcpu_dev_is_visible(struct kobject *kobj,
	141	struct attribute *attr, int idx)
	142	{
	143	struct device *dev = kobj_to_dev(kobj);
	144	/*
	145	* Xen never offline cpu0 due to several restrictions
	146	* and assumptions. This basically doesn't add a sys control
	147	* to user, one cannot attempt to offline BSP.
	148	*/
	149	return dev->id ? attr->mode : 0;
	150	}
	151
	152	static const struct attribute_group pcpu_dev_group = {
	153	.attrs = pcpu_dev_attrs,
	154	.is_visible = pcpu_dev_is_visible,
	155	};
	156
	157	static const struct attribute_group *pcpu_dev_groups[] = {
	158	&pcpu_dev_group,
	159	NULL
	160	};
	161
f65c9bb3 LJ	162	static bool xen_pcpu_online(uint32_t flags)
	163	{
	164	return !!(flags & XEN_PCPU_FLAGS_ONLINE);
	165	}
	166
	167	static void pcpu_online_status(struct xenpf_pcpuinfo *info,
	168	struct pcpu *pcpu)
	169	{
	170	if (xen_pcpu_online(info->flags) &&
	171	!xen_pcpu_online(pcpu->flags)) {
	172	/* the pcpu is onlined */
	173	pcpu->flags \|= XEN_PCPU_FLAGS_ONLINE;
	174	kobject_uevent(&pcpu->dev.kobj, KOBJ_ONLINE);
	175	} else if (!xen_pcpu_online(info->flags) &&
	176	xen_pcpu_online(pcpu->flags)) {
	177	/* The pcpu is offlined */
	178	pcpu->flags &= ~XEN_PCPU_FLAGS_ONLINE;
	179	kobject_uevent(&pcpu->dev.kobj, KOBJ_OFFLINE);
	180	}
	181	}
	182
	183	static struct pcpu *get_pcpu(uint32_t cpu_id)
	184	{
	185	struct pcpu *pcpu;
	186
	187	list_for_each_entry(pcpu, &xen_pcpus, list) {
	188	if (pcpu->cpu_id == cpu_id)
	189	return pcpu;
	190	}
	191
	192	return NULL;
	193	}
	194
	195	static void pcpu_release(struct device *dev)
	196	{
	197	struct pcpu *pcpu = container_of(dev, struct pcpu, dev);
	198
	199	list_del(&pcpu->list);
	200	kfree(pcpu);
	201	}
	202
	203	static void unregister_and_remove_pcpu(struct pcpu *pcpu)
	204	{
	205	struct device *dev;
	206
	207	if (!pcpu)
	208	return;
	209
	210	dev = &pcpu->dev;
f65c9bb3 LJ	211	/* pcpu remove would be implicitly done */
	212	device_unregister(dev);
	213	}
	214
	215	static int register_pcpu(struct pcpu *pcpu)
	216	{
	217	struct device *dev;
	218	int err = -EINVAL;
	219
	220	if (!pcpu)
	221	return err;
	222
	223	dev = &pcpu->dev;
	224	dev->bus = &xen_pcpu_subsys;
	225	dev->id = pcpu->cpu_id;
	226	dev->release = pcpu_release;
4644e5ab	227	dev->groups = pcpu_dev_groups;
f65c9bb3 LJ	228
	229	err = device_register(dev);
	230	if (err) {
	231	pcpu_release(dev);
	232	return err;
	233	}
	234
f65c9bb3 LJ	235	return 0;
	236	}
	237
	238	static struct pcpu create_and_register_pcpu(struct xenpf_pcpuinfo info)
	239	{
	240	struct pcpu *pcpu;
	241	int err;
	242
	243	if (info->flags & XEN_PCPU_FLAGS_INVALID)
	244	return ERR_PTR(-ENODEV);
	245
	246	pcpu = kzalloc(sizeof(struct pcpu), GFP_KERNEL);
	247	if (!pcpu)
	248	return ERR_PTR(-ENOMEM);
	249
	250	INIT_LIST_HEAD(&pcpu->list);
	251	pcpu->cpu_id = info->xen_cpuid;
	252	pcpu->flags = info->flags;
	253
	254	/* Need hold on xen_pcpu_lock before pcpu list manipulations */
	255	list_add_tail(&pcpu->list, &xen_pcpus);
	256
	257	err = register_pcpu(pcpu);
	258	if (err) {
283c0972	259	pr_warn("Failed to register pcpu%u\n", info->xen_cpuid);
f65c9bb3 LJ	260	return ERR_PTR(-ENOENT);
	261	}
	262
	263	return pcpu;
	264	}
	265
	266	/*
	267	* Caller should hold the xen_pcpu_lock
	268	*/
	269	static int sync_pcpu(uint32_t cpu, uint32_t *max_cpu)
	270	{
	271	int ret;
	272	struct pcpu *pcpu = NULL;
	273	struct xenpf_pcpuinfo *info;
	274	struct xen_platform_op op = {
	275	.cmd = XENPF_get_cpuinfo,
	276	.interface_version = XENPF_INTERFACE_VERSION,
	277	.u.pcpu_info.xen_cpuid = cpu,
	278	};
	279
cfafae94	280	ret = HYPERVISOR_platform_op(&op);
f65c9bb3 LJ	281	if (ret)
	282	return ret;
	283
	284	info = &op.u.pcpu_info;
	285	if (max_cpu)
	286	*max_cpu = info->max_present;
	287
	288	pcpu = get_pcpu(cpu);
	289
	290	/*
	291	* Only those at cpu present map has its sys interface.
	292	*/
	293	if (info->flags & XEN_PCPU_FLAGS_INVALID) {
4f8c8527	294	unregister_and_remove_pcpu(pcpu);
f65c9bb3 LJ	295	return 0;
	296	}
	297
	298	if (!pcpu) {
	299	pcpu = create_and_register_pcpu(info);
	300	if (IS_ERR_OR_NULL(pcpu))
	301	return -ENODEV;
	302	} else
	303	pcpu_online_status(info, pcpu);
	304
	305	return 0;
	306	}
	307
	308	/*
	309	* Sync dom0's pcpu information with xen hypervisor's
	310	*/
	311	static int xen_sync_pcpus(void)
	312	{
	313	/*
	314	* Boot cpu always have cpu_id 0 in xen
	315	*/
	316	uint32_t cpu = 0, max_cpu = 0;
	317	int err = 0;
	318	struct pcpu pcpu, tmp;
	319
	320	mutex_lock(&xen_pcpu_lock);
	321
	322	while (!err && (cpu <= max_cpu)) {
	323	err = sync_pcpu(cpu, &max_cpu);
	324	cpu++;
	325	}
	326
	327	if (err)
	328	list_for_each_entry_safe(pcpu, tmp, &xen_pcpus, list)
	329	unregister_and_remove_pcpu(pcpu);
	330
	331	mutex_unlock(&xen_pcpu_lock);
	332
	333	return err;
	334	}
	335
	336	static void xen_pcpu_work_fn(struct work_struct *work)
	337	{
	338	xen_sync_pcpus();
	339	}
	340	static DECLARE_WORK(xen_pcpu_work, xen_pcpu_work_fn);
	341
	342	static irqreturn_t xen_pcpu_interrupt(int irq, void *dev_id)
	343	{
	344	schedule_work(&xen_pcpu_work);
	345	return IRQ_HANDLED;
	346	}
	347
39adc483 LJ	348	/* Sync with Xen hypervisor after cpu hotadded */
	349	void xen_pcpu_hotplug_sync(void)
	350	{
	351	schedule_work(&xen_pcpu_work);
	352	}
	353	EXPORT_SYMBOL_GPL(xen_pcpu_hotplug_sync);
	354
	355	/*
	356	* For hypervisor presented cpu, return logic cpu id;
	357	* For hypervisor non-presented cpu, return -ENODEV.
	358	*/
	359	int xen_pcpu_id(uint32_t acpi_id)
	360	{
	361	int cpu_id = 0, max_id = 0;
	362	struct xen_platform_op op;
	363
	364	op.cmd = XENPF_get_cpuinfo;
	365	while (cpu_id <= max_id) {
	366	op.u.pcpu_info.xen_cpuid = cpu_id;
cfafae94	367	if (HYPERVISOR_platform_op(&op)) {
39adc483 LJ	368	cpu_id++;
	369	continue;
	370	}
	371
	372	if (acpi_id == op.u.pcpu_info.acpi_id)
	373	return cpu_id;
	374	if (op.u.pcpu_info.max_present > max_id)
	375	max_id = op.u.pcpu_info.max_present;
	376	cpu_id++;
	377	}
	378
	379	return -ENODEV;
	380	}
	381	EXPORT_SYMBOL_GPL(xen_pcpu_id);
	382
f65c9bb3 LJ	383	static int __init xen_pcpu_init(void)
	384	{
	385	int irq, ret;
	386
	387	if (!xen_initial_domain())
	388	return -ENODEV;
	389
	390	irq = bind_virq_to_irqhandler(VIRQ_PCPU_STATE, 0,
	391	xen_pcpu_interrupt, 0,
	392	"xen-pcpu", NULL);
	393	if (irq < 0) {
283c0972	394	pr_warn("Failed to bind pcpu virq\n");
f65c9bb3 LJ	395	return irq;
	396	}
	397
	398	ret = subsys_system_register(&xen_pcpu_subsys, NULL);
	399	if (ret) {
283c0972	400	pr_warn("Failed to register pcpu subsys\n");
f65c9bb3 LJ	401	goto err1;
	402	}
	403
	404	ret = xen_sync_pcpus();
	405	if (ret) {
283c0972	406	pr_warn("Failed to sync pcpu info\n");
f65c9bb3 LJ	407	goto err2;
	408	}
	409
	410	return 0;
	411
	412	err2:
	413	bus_unregister(&xen_pcpu_subsys);
	414	err1:
	415	unbind_from_irqhandler(irq, NULL);
	416	return ret;
	417	}
	418	arch_initcall(xen_pcpu_init);