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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
34#define pr_fmt(fmt) "xen_cpu: " fmt
35
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>
43#include <xen/acpi.h>
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
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 */
57struct pcpu {
58 struct list_head list;
59 struct device dev;
60 uint32_t cpu_id;
61 uint32_t flags;
62};
63
64static struct bus_type xen_pcpu_subsys = {
65 .name = "xen_cpu",
66 .dev_name = "xen_cpu",
67};
68
69static DEFINE_MUTEX(xen_pcpu_lock);
70
71static LIST_HEAD(xen_pcpus);
72
73static 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
81 return HYPERVISOR_dom0_op(&op);
82}
83
84static 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
92 return HYPERVISOR_dom0_op(&op);
93}
94
95static 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
104static 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}
133static DEVICE_ATTR(online, S_IRUGO | S_IWUSR, show_online, store_online);
134
135static bool xen_pcpu_online(uint32_t flags)
136{
137 return !!(flags & XEN_PCPU_FLAGS_ONLINE);
138}
139
140static void pcpu_online_status(struct xenpf_pcpuinfo *info,
141 struct pcpu *pcpu)
142{
143 if (xen_pcpu_online(info->flags) &&
144 !xen_pcpu_online(pcpu->flags)) {
145 /* the pcpu is onlined */
146 pcpu->flags |= XEN_PCPU_FLAGS_ONLINE;
147 kobject_uevent(&pcpu->dev.kobj, KOBJ_ONLINE);
148 } else if (!xen_pcpu_online(info->flags) &&
149 xen_pcpu_online(pcpu->flags)) {
150 /* The pcpu is offlined */
151 pcpu->flags &= ~XEN_PCPU_FLAGS_ONLINE;
152 kobject_uevent(&pcpu->dev.kobj, KOBJ_OFFLINE);
153 }
154}
155
156static struct pcpu *get_pcpu(uint32_t cpu_id)
157{
158 struct pcpu *pcpu;
159
160 list_for_each_entry(pcpu, &xen_pcpus, list) {
161 if (pcpu->cpu_id == cpu_id)
162 return pcpu;
163 }
164
165 return NULL;
166}
167
168static void pcpu_release(struct device *dev)
169{
170 struct pcpu *pcpu = container_of(dev, struct pcpu, dev);
171
172 list_del(&pcpu->list);
173 kfree(pcpu);
174}
175
176static void unregister_and_remove_pcpu(struct pcpu *pcpu)
177{
178 struct device *dev;
179
180 if (!pcpu)
181 return;
182
183 dev = &pcpu->dev;
184 if (dev->id)
185 device_remove_file(dev, &dev_attr_online);
186
187 /* pcpu remove would be implicitly done */
188 device_unregister(dev);
189}
190
191static int register_pcpu(struct pcpu *pcpu)
192{
193 struct device *dev;
194 int err = -EINVAL;
195
196 if (!pcpu)
197 return err;
198
199 dev = &pcpu->dev;
200 dev->bus = &xen_pcpu_subsys;
201 dev->id = pcpu->cpu_id;
202 dev->release = pcpu_release;
203
204 err = device_register(dev);
205 if (err) {
206 pcpu_release(dev);
207 return err;
208 }
209
210 /*
211 * Xen never offline cpu0 due to several restrictions
212 * and assumptions. This basically doesn't add a sys control
213 * to user, one cannot attempt to offline BSP.
214 */
215 if (dev->id) {
216 err = device_create_file(dev, &dev_attr_online);
217 if (err) {
218 device_unregister(dev);
219 return err;
220 }
221 }
222
223 return 0;
224}
225
226static struct pcpu *create_and_register_pcpu(struct xenpf_pcpuinfo *info)
227{
228 struct pcpu *pcpu;
229 int err;
230
231 if (info->flags & XEN_PCPU_FLAGS_INVALID)
232 return ERR_PTR(-ENODEV);
233
234 pcpu = kzalloc(sizeof(struct pcpu), GFP_KERNEL);
235 if (!pcpu)
236 return ERR_PTR(-ENOMEM);
237
238 INIT_LIST_HEAD(&pcpu->list);
239 pcpu->cpu_id = info->xen_cpuid;
240 pcpu->flags = info->flags;
241
242 /* Need hold on xen_pcpu_lock before pcpu list manipulations */
243 list_add_tail(&pcpu->list, &xen_pcpus);
244
245 err = register_pcpu(pcpu);
246 if (err) {
247 pr_warn("Failed to register pcpu%u\n", info->xen_cpuid);
248 return ERR_PTR(-ENOENT);
249 }
250
251 return pcpu;
252}
253
254/*
255 * Caller should hold the xen_pcpu_lock
256 */
257static int sync_pcpu(uint32_t cpu, uint32_t *max_cpu)
258{
259 int ret;
260 struct pcpu *pcpu = NULL;
261 struct xenpf_pcpuinfo *info;
262 struct xen_platform_op op = {
263 .cmd = XENPF_get_cpuinfo,
264 .interface_version = XENPF_INTERFACE_VERSION,
265 .u.pcpu_info.xen_cpuid = cpu,
266 };
267
268 ret = HYPERVISOR_dom0_op(&op);
269 if (ret)
270 return ret;
271
272 info = &op.u.pcpu_info;
273 if (max_cpu)
274 *max_cpu = info->max_present;
275
276 pcpu = get_pcpu(cpu);
277
278 /*
279 * Only those at cpu present map has its sys interface.
280 */
281 if (info->flags & XEN_PCPU_FLAGS_INVALID) {
282 unregister_and_remove_pcpu(pcpu);
283 return 0;
284 }
285
286 if (!pcpu) {
287 pcpu = create_and_register_pcpu(info);
288 if (IS_ERR_OR_NULL(pcpu))
289 return -ENODEV;
290 } else
291 pcpu_online_status(info, pcpu);
292
293 return 0;
294}
295
296/*
297 * Sync dom0's pcpu information with xen hypervisor's
298 */
299static int xen_sync_pcpus(void)
300{
301 /*
302 * Boot cpu always have cpu_id 0 in xen
303 */
304 uint32_t cpu = 0, max_cpu = 0;
305 int err = 0;
306 struct pcpu *pcpu, *tmp;
307
308 mutex_lock(&xen_pcpu_lock);
309
310 while (!err && (cpu <= max_cpu)) {
311 err = sync_pcpu(cpu, &max_cpu);
312 cpu++;
313 }
314
315 if (err)
316 list_for_each_entry_safe(pcpu, tmp, &xen_pcpus, list)
317 unregister_and_remove_pcpu(pcpu);
318
319 mutex_unlock(&xen_pcpu_lock);
320
321 return err;
322}
323
324static void xen_pcpu_work_fn(struct work_struct *work)
325{
326 xen_sync_pcpus();
327}
328static DECLARE_WORK(xen_pcpu_work, xen_pcpu_work_fn);
329
330static irqreturn_t xen_pcpu_interrupt(int irq, void *dev_id)
331{
332 schedule_work(&xen_pcpu_work);
333 return IRQ_HANDLED;
334}
335
336/* Sync with Xen hypervisor after cpu hotadded */
337void xen_pcpu_hotplug_sync(void)
338{
339 schedule_work(&xen_pcpu_work);
340}
341EXPORT_SYMBOL_GPL(xen_pcpu_hotplug_sync);
342
343/*
344 * For hypervisor presented cpu, return logic cpu id;
345 * For hypervisor non-presented cpu, return -ENODEV.
346 */
347int xen_pcpu_id(uint32_t acpi_id)
348{
349 int cpu_id = 0, max_id = 0;
350 struct xen_platform_op op;
351
352 op.cmd = XENPF_get_cpuinfo;
353 while (cpu_id <= max_id) {
354 op.u.pcpu_info.xen_cpuid = cpu_id;
355 if (HYPERVISOR_dom0_op(&op)) {
356 cpu_id++;
357 continue;
358 }
359
360 if (acpi_id == op.u.pcpu_info.acpi_id)
361 return cpu_id;
362 if (op.u.pcpu_info.max_present > max_id)
363 max_id = op.u.pcpu_info.max_present;
364 cpu_id++;
365 }
366
367 return -ENODEV;
368}
369EXPORT_SYMBOL_GPL(xen_pcpu_id);
370
371static int __init xen_pcpu_init(void)
372{
373 int irq, ret;
374
375 if (!xen_initial_domain())
376 return -ENODEV;
377
378 irq = bind_virq_to_irqhandler(VIRQ_PCPU_STATE, 0,
379 xen_pcpu_interrupt, 0,
380 "xen-pcpu", NULL);
381 if (irq < 0) {
382 pr_warn("Failed to bind pcpu virq\n");
383 return irq;
384 }
385
386 ret = subsys_system_register(&xen_pcpu_subsys, NULL);
387 if (ret) {
388 pr_warn("Failed to register pcpu subsys\n");
389 goto err1;
390 }
391
392 ret = xen_sync_pcpus();
393 if (ret) {
394 pr_warn("Failed to sync pcpu info\n");
395 goto err2;
396 }
397
398 return 0;
399
400err2:
401 bus_unregister(&xen_pcpu_subsys);
402err1:
403 unbind_from_irqhandler(irq, NULL);
404 return ret;
405}
406arch_initcall(xen_pcpu_init);