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_platform_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_platform_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 struct attribute *pcpu_dev_attrs[] = {
136 &dev_attr_online.attr,
137 NULL
138};
139
140static 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
152static const struct attribute_group pcpu_dev_group = {
153 .attrs = pcpu_dev_attrs,
154 .is_visible = pcpu_dev_is_visible,
155};
156
157static const struct attribute_group *pcpu_dev_groups[] = {
158 &pcpu_dev_group,
159 NULL
160};
161
162static bool xen_pcpu_online(uint32_t flags)
163{
164 return !!(flags & XEN_PCPU_FLAGS_ONLINE);
165}
166
167static 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
183static 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
195static 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
203static void unregister_and_remove_pcpu(struct pcpu *pcpu)
204{
205 struct device *dev;
206
207 if (!pcpu)
208 return;
209
210 dev = &pcpu->dev;
211 /* pcpu remove would be implicitly done */
212 device_unregister(dev);
213}
214
215static 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;
227 dev->groups = pcpu_dev_groups;
228
229 err = device_register(dev);
230 if (err) {
231 pcpu_release(dev);
232 return err;
233 }
234
235 return 0;
236}
237
238static 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) {
259 pr_warn("Failed to register pcpu%u\n", info->xen_cpuid);
260 return ERR_PTR(-ENOENT);
261 }
262
263 return pcpu;
264}
265
266/*
267 * Caller should hold the xen_pcpu_lock
268 */
269static 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
280 ret = HYPERVISOR_platform_op(&op);
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) {
294 unregister_and_remove_pcpu(pcpu);
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 */
311static 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
336static void xen_pcpu_work_fn(struct work_struct *work)
337{
338 xen_sync_pcpus();
339}
340static DECLARE_WORK(xen_pcpu_work, xen_pcpu_work_fn);
341
342static irqreturn_t xen_pcpu_interrupt(int irq, void *dev_id)
343{
344 schedule_work(&xen_pcpu_work);
345 return IRQ_HANDLED;
346}
347
348/* Sync with Xen hypervisor after cpu hotadded */
349void xen_pcpu_hotplug_sync(void)
350{
351 schedule_work(&xen_pcpu_work);
352}
353EXPORT_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 */
359int 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;
367 if (HYPERVISOR_platform_op(&op)) {
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}
381EXPORT_SYMBOL_GPL(xen_pcpu_id);
382
383static 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) {
394 pr_warn("Failed to bind pcpu virq\n");
395 return irq;
396 }
397
398 ret = subsys_system_register(&xen_pcpu_subsys, NULL);
399 if (ret) {
400 pr_warn("Failed to register pcpu subsys\n");
401 goto err1;
402 }
403
404 ret = xen_sync_pcpus();
405 if (ret) {
406 pr_warn("Failed to sync pcpu info\n");
407 goto err2;
408 }
409
410 return 0;
411
412err2:
413 bus_unregister(&xen_pcpu_subsys);
414err1:
415 unbind_from_irqhandler(irq, NULL);
416 return ret;
417}
418arch_initcall(xen_pcpu_init);
419