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8#include <linux/kernel.h>
9#include <linux/cpumask.h>
10#include <linux/module.h>
11#include <linux/init.h>
12#include <linux/types.h>
13#include <linux/kthread.h>
14#include <uapi/linux/sched/types.h>
15#include <linux/freezer.h>
16#include <linux/cpu.h>
17#include <linux/tick.h>
18#include <linux/slab.h>
19#include <linux/acpi.h>
20#include <asm/mwait.h>
21#include <xen/xen.h>
22
23#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
24#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
25#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
26static DEFINE_MUTEX(isolated_cpus_lock);
27static DEFINE_MUTEX(round_robin_lock);
28
29static unsigned long power_saving_mwait_eax;
30
31static unsigned char tsc_detected_unstable;
32static unsigned char tsc_marked_unstable;
33
34static void power_saving_mwait_init(void)
35{
36 unsigned int eax, ebx, ecx, edx;
37 unsigned int highest_cstate = 0;
38 unsigned int highest_subcstate = 0;
39 int i;
40
41 if (!boot_cpu_has(X86_FEATURE_MWAIT))
42 return;
43 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
44 return;
45
46 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
47
48 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
49 !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
50 return;
51
52 edx >>= MWAIT_SUBSTATE_SIZE;
53 for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
54 if (edx & MWAIT_SUBSTATE_MASK) {
55 highest_cstate = i;
56 highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
57 }
58 }
59 power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
60 (highest_subcstate - 1);
61
62#if defined(CONFIG_X86)
63 switch (boot_cpu_data.x86_vendor) {
64 case X86_VENDOR_HYGON:
65 case X86_VENDOR_AMD:
66 case X86_VENDOR_INTEL:
67 case X86_VENDOR_ZHAOXIN:
68
69
70
71
72 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
73 tsc_detected_unstable = 1;
74 break;
75 default:
76
77 tsc_detected_unstable = 1;
78 }
79#endif
80}
81
82static unsigned long cpu_weight[NR_CPUS];
83static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
84static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
85static void round_robin_cpu(unsigned int tsk_index)
86{
87 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
88 cpumask_var_t tmp;
89 int cpu;
90 unsigned long min_weight = -1;
91 unsigned long preferred_cpu;
92
93 if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
94 return;
95
96 mutex_lock(&round_robin_lock);
97 cpumask_clear(tmp);
98 for_each_cpu(cpu, pad_busy_cpus)
99 cpumask_or(tmp, tmp, topology_sibling_cpumask(cpu));
100 cpumask_andnot(tmp, cpu_online_mask, tmp);
101
102 if (cpumask_empty(tmp))
103 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
104 if (cpumask_empty(tmp)) {
105 mutex_unlock(&round_robin_lock);
106 free_cpumask_var(tmp);
107 return;
108 }
109 for_each_cpu(cpu, tmp) {
110 if (cpu_weight[cpu] < min_weight) {
111 min_weight = cpu_weight[cpu];
112 preferred_cpu = cpu;
113 }
114 }
115
116 if (tsk_in_cpu[tsk_index] != -1)
117 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
118 tsk_in_cpu[tsk_index] = preferred_cpu;
119 cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
120 cpu_weight[preferred_cpu]++;
121 mutex_unlock(&round_robin_lock);
122
123 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
124
125 free_cpumask_var(tmp);
126}
127
128static void exit_round_robin(unsigned int tsk_index)
129{
130 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
131
132 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
133 tsk_in_cpu[tsk_index] = -1;
134}
135
136static unsigned int idle_pct = 5;
137static unsigned int round_robin_time = 1;
138static int power_saving_thread(void *data)
139{
140 int do_sleep;
141 unsigned int tsk_index = (unsigned long)data;
142 u64 last_jiffies = 0;
143
144 sched_set_fifo_low(current);
145
146 while (!kthread_should_stop()) {
147 unsigned long expire_time;
148
149
150 expire_time = last_jiffies + round_robin_time * HZ;
151 if (time_before(expire_time, jiffies)) {
152 last_jiffies = jiffies;
153 round_robin_cpu(tsk_index);
154 }
155
156 do_sleep = 0;
157
158 expire_time = jiffies + HZ * (100 - idle_pct) / 100;
159
160 while (!need_resched()) {
161 if (tsc_detected_unstable && !tsc_marked_unstable) {
162
163 mark_tsc_unstable("TSC halts in idle");
164 tsc_marked_unstable = 1;
165 }
166 local_irq_disable();
167 tick_broadcast_enable();
168 tick_broadcast_enter();
169 stop_critical_timings();
170
171 mwait_idle_with_hints(power_saving_mwait_eax, 1);
172
173 start_critical_timings();
174 tick_broadcast_exit();
175 local_irq_enable();
176
177 if (time_before(expire_time, jiffies)) {
178 do_sleep = 1;
179 break;
180 }
181 }
182
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189
190
191
192 if (unlikely(do_sleep))
193 schedule_timeout_killable(HZ * idle_pct / 100);
194
195
196
197
198
199 if (unlikely(need_resched()))
200 schedule();
201 }
202
203 exit_round_robin(tsk_index);
204 return 0;
205}
206
207static struct task_struct *ps_tsks[NR_CPUS];
208static unsigned int ps_tsk_num;
209static int create_power_saving_task(void)
210{
211 int rc;
212
213 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
214 (void *)(unsigned long)ps_tsk_num,
215 "acpi_pad/%d", ps_tsk_num);
216
217 if (IS_ERR(ps_tsks[ps_tsk_num])) {
218 rc = PTR_ERR(ps_tsks[ps_tsk_num]);
219 ps_tsks[ps_tsk_num] = NULL;
220 } else {
221 rc = 0;
222 ps_tsk_num++;
223 }
224
225 return rc;
226}
227
228static void destroy_power_saving_task(void)
229{
230 if (ps_tsk_num > 0) {
231 ps_tsk_num--;
232 kthread_stop(ps_tsks[ps_tsk_num]);
233 ps_tsks[ps_tsk_num] = NULL;
234 }
235}
236
237static void set_power_saving_task_num(unsigned int num)
238{
239 if (num > ps_tsk_num) {
240 while (ps_tsk_num < num) {
241 if (create_power_saving_task())
242 return;
243 }
244 } else if (num < ps_tsk_num) {
245 while (ps_tsk_num > num)
246 destroy_power_saving_task();
247 }
248}
249
250static void acpi_pad_idle_cpus(unsigned int num_cpus)
251{
252 cpus_read_lock();
253
254 num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
255 set_power_saving_task_num(num_cpus);
256
257 cpus_read_unlock();
258}
259
260static uint32_t acpi_pad_idle_cpus_num(void)
261{
262 return ps_tsk_num;
263}
264
265static ssize_t rrtime_store(struct device *dev,
266 struct device_attribute *attr, const char *buf, size_t count)
267{
268 unsigned long num;
269
270 if (kstrtoul(buf, 0, &num))
271 return -EINVAL;
272 if (num < 1 || num >= 100)
273 return -EINVAL;
274 mutex_lock(&isolated_cpus_lock);
275 round_robin_time = num;
276 mutex_unlock(&isolated_cpus_lock);
277 return count;
278}
279
280static ssize_t rrtime_show(struct device *dev,
281 struct device_attribute *attr, char *buf)
282{
283 return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time);
284}
285static DEVICE_ATTR_RW(rrtime);
286
287static ssize_t idlepct_store(struct device *dev,
288 struct device_attribute *attr, const char *buf, size_t count)
289{
290 unsigned long num;
291
292 if (kstrtoul(buf, 0, &num))
293 return -EINVAL;
294 if (num < 1 || num >= 100)
295 return -EINVAL;
296 mutex_lock(&isolated_cpus_lock);
297 idle_pct = num;
298 mutex_unlock(&isolated_cpus_lock);
299 return count;
300}
301
302static ssize_t idlepct_show(struct device *dev,
303 struct device_attribute *attr, char *buf)
304{
305 return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct);
306}
307static DEVICE_ATTR_RW(idlepct);
308
309static ssize_t idlecpus_store(struct device *dev,
310 struct device_attribute *attr, const char *buf, size_t count)
311{
312 unsigned long num;
313
314 if (kstrtoul(buf, 0, &num))
315 return -EINVAL;
316 mutex_lock(&isolated_cpus_lock);
317 acpi_pad_idle_cpus(num);
318 mutex_unlock(&isolated_cpus_lock);
319 return count;
320}
321
322static ssize_t idlecpus_show(struct device *dev,
323 struct device_attribute *attr, char *buf)
324{
325 return cpumap_print_to_pagebuf(false, buf,
326 to_cpumask(pad_busy_cpus_bits));
327}
328
329static DEVICE_ATTR_RW(idlecpus);
330
331static int acpi_pad_add_sysfs(struct acpi_device *device)
332{
333 int result;
334
335 result = device_create_file(&device->dev, &dev_attr_idlecpus);
336 if (result)
337 return -ENODEV;
338 result = device_create_file(&device->dev, &dev_attr_idlepct);
339 if (result) {
340 device_remove_file(&device->dev, &dev_attr_idlecpus);
341 return -ENODEV;
342 }
343 result = device_create_file(&device->dev, &dev_attr_rrtime);
344 if (result) {
345 device_remove_file(&device->dev, &dev_attr_idlecpus);
346 device_remove_file(&device->dev, &dev_attr_idlepct);
347 return -ENODEV;
348 }
349 return 0;
350}
351
352static void acpi_pad_remove_sysfs(struct acpi_device *device)
353{
354 device_remove_file(&device->dev, &dev_attr_idlecpus);
355 device_remove_file(&device->dev, &dev_attr_idlepct);
356 device_remove_file(&device->dev, &dev_attr_rrtime);
357}
358
359
360
361
362
363static int acpi_pad_pur(acpi_handle handle)
364{
365 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
366 union acpi_object *package;
367 int num = -1;
368
369 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
370 return num;
371
372 if (!buffer.length || !buffer.pointer)
373 return num;
374
375 package = buffer.pointer;
376
377 if (package->type == ACPI_TYPE_PACKAGE &&
378 package->package.count == 2 &&
379 package->package.elements[0].integer.value == 1)
380
381 num = package->package.elements[1].integer.value;
382
383 kfree(buffer.pointer);
384 return num;
385}
386
387static void acpi_pad_handle_notify(acpi_handle handle)
388{
389 int num_cpus;
390 uint32_t idle_cpus;
391 struct acpi_buffer param = {
392 .length = 4,
393 .pointer = (void *)&idle_cpus,
394 };
395
396 mutex_lock(&isolated_cpus_lock);
397 num_cpus = acpi_pad_pur(handle);
398 if (num_cpus < 0) {
399 mutex_unlock(&isolated_cpus_lock);
400 return;
401 }
402 acpi_pad_idle_cpus(num_cpus);
403 idle_cpus = acpi_pad_idle_cpus_num();
404 acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m);
405 mutex_unlock(&isolated_cpus_lock);
406}
407
408static void acpi_pad_notify(acpi_handle handle, u32 event,
409 void *data)
410{
411 struct acpi_device *device = data;
412
413 switch (event) {
414 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
415 acpi_pad_handle_notify(handle);
416 acpi_bus_generate_netlink_event(device->pnp.device_class,
417 dev_name(&device->dev), event, 0);
418 break;
419 default:
420 pr_warn("Unsupported event [0x%x]\n", event);
421 break;
422 }
423}
424
425static int acpi_pad_add(struct acpi_device *device)
426{
427 acpi_status status;
428
429 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
430 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
431
432 if (acpi_pad_add_sysfs(device))
433 return -ENODEV;
434
435 status = acpi_install_notify_handler(device->handle,
436 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
437 if (ACPI_FAILURE(status)) {
438 acpi_pad_remove_sysfs(device);
439 return -ENODEV;
440 }
441
442 return 0;
443}
444
445static int acpi_pad_remove(struct acpi_device *device)
446{
447 mutex_lock(&isolated_cpus_lock);
448 acpi_pad_idle_cpus(0);
449 mutex_unlock(&isolated_cpus_lock);
450
451 acpi_remove_notify_handler(device->handle,
452 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
453 acpi_pad_remove_sysfs(device);
454 return 0;
455}
456
457static const struct acpi_device_id pad_device_ids[] = {
458 {"ACPI000C", 0},
459 {"", 0},
460};
461MODULE_DEVICE_TABLE(acpi, pad_device_ids);
462
463static struct acpi_driver acpi_pad_driver = {
464 .name = "processor_aggregator",
465 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
466 .ids = pad_device_ids,
467 .ops = {
468 .add = acpi_pad_add,
469 .remove = acpi_pad_remove,
470 },
471};
472
473static int __init acpi_pad_init(void)
474{
475
476 if (xen_initial_domain())
477 return -ENODEV;
478
479 power_saving_mwait_init();
480 if (power_saving_mwait_eax == 0)
481 return -EINVAL;
482
483 return acpi_bus_register_driver(&acpi_pad_driver);
484}
485
486static void __exit acpi_pad_exit(void)
487{
488 acpi_bus_unregister_driver(&acpi_pad_driver);
489}
490
491module_init(acpi_pad_init);
492module_exit(acpi_pad_exit);
493MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
494MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
495MODULE_LICENSE("GPL");
496
