1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * acpi_pad.c ACPI Processor Aggregator Driver 4 * 5 * Copyright (c) 2009, Intel Corporation. 6 */ 7 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 <linux/perf_event.h> 21 #include <asm/mwait.h> 22 #include <xen/xen.h> 23 24 #define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad" 25 #define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator" 26 #define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80 27 static DEFINE_MUTEX(isolated_cpus_lock); 28 static DEFINE_MUTEX(round_robin_lock); 29 30 static unsigned long power_saving_mwait_eax; 31 32 static unsigned char tsc_detected_unstable; 33 static unsigned char tsc_marked_unstable; 34 35 static void power_saving_mwait_init(void) 36 { 37 unsigned int eax, ebx, ecx, edx; 38 unsigned int highest_cstate = 0; 39 unsigned int highest_subcstate = 0; 40 int i; 41 42 if (!boot_cpu_has(X86_FEATURE_MWAIT)) 43 return; 44 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF) 45 return; 46 47 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx); 48 49 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) || 50 !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) 51 return; 52 53 edx >>= MWAIT_SUBSTATE_SIZE; 54 for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) { 55 if (edx & MWAIT_SUBSTATE_MASK) { 56 highest_cstate = i; 57 highest_subcstate = edx & MWAIT_SUBSTATE_MASK; 58 } 59 } 60 power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) | 61 (highest_subcstate - 1); 62 63 #if defined(CONFIG_X86) 64 switch (boot_cpu_data.x86_vendor) { 65 case X86_VENDOR_HYGON: 66 case X86_VENDOR_AMD: 67 case X86_VENDOR_INTEL: 68 case X86_VENDOR_ZHAOXIN: 69 case X86_VENDOR_CENTAUR: 70 /* 71 * AMD Fam10h TSC will tick in all 72 * C/P/S0/S1 states when this bit is set. 73 */ 74 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) 75 tsc_detected_unstable = 1; 76 break; 77 default: 78 /* TSC could halt in idle */ 79 tsc_detected_unstable = 1; 80 } 81 #endif 82 } 83 84 static unsigned long cpu_weight[NR_CPUS]; 85 static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1}; 86 static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS); 87 static void round_robin_cpu(unsigned int tsk_index) 88 { 89 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); 90 cpumask_var_t tmp; 91 int cpu; 92 unsigned long min_weight = -1; 93 unsigned long preferred_cpu; 94 95 if (!alloc_cpumask_var(&tmp, GFP_KERNEL)) 96 return; 97 98 mutex_lock(&round_robin_lock); 99 cpumask_clear(tmp); 100 for_each_cpu(cpu, pad_busy_cpus) 101 cpumask_or(tmp, tmp, topology_sibling_cpumask(cpu)); 102 cpumask_andnot(tmp, cpu_online_mask, tmp); 103 /* avoid HT sibilings if possible */ 104 if (cpumask_empty(tmp)) 105 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus); 106 if (cpumask_empty(tmp)) { 107 mutex_unlock(&round_robin_lock); 108 free_cpumask_var(tmp); 109 return; 110 } 111 for_each_cpu(cpu, tmp) { 112 if (cpu_weight[cpu] < min_weight) { 113 min_weight = cpu_weight[cpu]; 114 preferred_cpu = cpu; 115 } 116 } 117 118 if (tsk_in_cpu[tsk_index] != -1) 119 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); 120 tsk_in_cpu[tsk_index] = preferred_cpu; 121 cpumask_set_cpu(preferred_cpu, pad_busy_cpus); 122 cpu_weight[preferred_cpu]++; 123 mutex_unlock(&round_robin_lock); 124 125 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu)); 126 127 free_cpumask_var(tmp); 128 } 129 130 static void exit_round_robin(unsigned int tsk_index) 131 { 132 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); 133 134 if (tsk_in_cpu[tsk_index] != -1) { 135 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); 136 tsk_in_cpu[tsk_index] = -1; 137 } 138 } 139 140 static unsigned int idle_pct = 5; /* percentage */ 141 static unsigned int round_robin_time = 1; /* second */ 142 static int power_saving_thread(void *data) 143 { 144 int do_sleep; 145 unsigned int tsk_index = (unsigned long)data; 146 u64 last_jiffies = 0; 147 148 sched_set_fifo_low(current); 149 150 while (!kthread_should_stop()) { 151 unsigned long expire_time; 152 153 /* round robin to cpus */ 154 expire_time = last_jiffies + round_robin_time * HZ; 155 if (time_before(expire_time, jiffies)) { 156 last_jiffies = jiffies; 157 round_robin_cpu(tsk_index); 158 } 159 160 do_sleep = 0; 161 162 expire_time = jiffies + HZ * (100 - idle_pct) / 100; 163 164 while (!need_resched()) { 165 if (tsc_detected_unstable && !tsc_marked_unstable) { 166 /* TSC could halt in idle, so notify users */ 167 mark_tsc_unstable("TSC halts in idle"); 168 tsc_marked_unstable = 1; 169 } 170 local_irq_disable(); 171 172 perf_lopwr_cb(true); 173 174 tick_broadcast_enable(); 175 tick_broadcast_enter(); 176 stop_critical_timings(); 177 178 mwait_idle_with_hints(power_saving_mwait_eax, 1); 179 180 start_critical_timings(); 181 tick_broadcast_exit(); 182 183 perf_lopwr_cb(false); 184 185 local_irq_enable(); 186 187 if (time_before(expire_time, jiffies)) { 188 do_sleep = 1; 189 break; 190 } 191 } 192 193 /* 194 * current sched_rt has threshold for rt task running time. 195 * When a rt task uses 95% CPU time, the rt thread will be 196 * scheduled out for 5% CPU time to not starve other tasks. But 197 * the mechanism only works when all CPUs have RT task running, 198 * as if one CPU hasn't RT task, RT task from other CPUs will 199 * borrow CPU time from this CPU and cause RT task use > 95% 200 * CPU time. To make 'avoid starvation' work, takes a nap here. 201 */ 202 if (unlikely(do_sleep)) 203 schedule_timeout_killable(HZ * idle_pct / 100); 204 205 /* If an external event has set the need_resched flag, then 206 * we need to deal with it, or this loop will continue to 207 * spin without calling __mwait(). 208 */ 209 if (unlikely(need_resched())) 210 schedule(); 211 } 212 213 exit_round_robin(tsk_index); 214 return 0; 215 } 216 217 static struct task_struct *ps_tsks[NR_CPUS]; 218 static unsigned int ps_tsk_num; 219 static int create_power_saving_task(void) 220 { 221 int rc; 222 223 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread, 224 (void *)(unsigned long)ps_tsk_num, 225 "acpi_pad/%d", ps_tsk_num); 226 227 if (IS_ERR(ps_tsks[ps_tsk_num])) { 228 rc = PTR_ERR(ps_tsks[ps_tsk_num]); 229 ps_tsks[ps_tsk_num] = NULL; 230 } else { 231 rc = 0; 232 ps_tsk_num++; 233 } 234 235 return rc; 236 } 237 238 static void destroy_power_saving_task(void) 239 { 240 if (ps_tsk_num > 0) { 241 ps_tsk_num--; 242 kthread_stop(ps_tsks[ps_tsk_num]); 243 ps_tsks[ps_tsk_num] = NULL; 244 } 245 } 246 247 static void set_power_saving_task_num(unsigned int num) 248 { 249 if (num > ps_tsk_num) { 250 while (ps_tsk_num < num) { 251 if (create_power_saving_task()) 252 return; 253 } 254 } else if (num < ps_tsk_num) { 255 while (ps_tsk_num > num) 256 destroy_power_saving_task(); 257 } 258 } 259 260 static void acpi_pad_idle_cpus(unsigned int num_cpus) 261 { 262 cpus_read_lock(); 263 264 num_cpus = min_t(unsigned int, num_cpus, num_online_cpus()); 265 set_power_saving_task_num(num_cpus); 266 267 cpus_read_unlock(); 268 } 269 270 static uint32_t acpi_pad_idle_cpus_num(void) 271 { 272 return ps_tsk_num; 273 } 274 275 static ssize_t rrtime_store(struct device *dev, 276 struct device_attribute *attr, const char *buf, size_t count) 277 { 278 unsigned long num; 279 280 if (kstrtoul(buf, 0, &num)) 281 return -EINVAL; 282 if (num < 1 || num >= 100) 283 return -EINVAL; 284 mutex_lock(&isolated_cpus_lock); 285 round_robin_time = num; 286 mutex_unlock(&isolated_cpus_lock); 287 return count; 288 } 289 290 static ssize_t rrtime_show(struct device *dev, 291 struct device_attribute *attr, char *buf) 292 { 293 return sysfs_emit(buf, "%d\n", round_robin_time); 294 } 295 static DEVICE_ATTR_RW(rrtime); 296 297 static ssize_t idlepct_store(struct device *dev, 298 struct device_attribute *attr, const char *buf, size_t count) 299 { 300 unsigned long num; 301 302 if (kstrtoul(buf, 0, &num)) 303 return -EINVAL; 304 if (num < 1 || num >= 100) 305 return -EINVAL; 306 mutex_lock(&isolated_cpus_lock); 307 idle_pct = num; 308 mutex_unlock(&isolated_cpus_lock); 309 return count; 310 } 311 312 static ssize_t idlepct_show(struct device *dev, 313 struct device_attribute *attr, char *buf) 314 { 315 return sysfs_emit(buf, "%d\n", idle_pct); 316 } 317 static DEVICE_ATTR_RW(idlepct); 318 319 static ssize_t idlecpus_store(struct device *dev, 320 struct device_attribute *attr, const char *buf, size_t count) 321 { 322 unsigned long num; 323 324 if (kstrtoul(buf, 0, &num)) 325 return -EINVAL; 326 mutex_lock(&isolated_cpus_lock); 327 acpi_pad_idle_cpus(num); 328 mutex_unlock(&isolated_cpus_lock); 329 return count; 330 } 331 332 static ssize_t idlecpus_show(struct device *dev, 333 struct device_attribute *attr, char *buf) 334 { 335 return cpumap_print_to_pagebuf(false, buf, 336 to_cpumask(pad_busy_cpus_bits)); 337 } 338 339 static DEVICE_ATTR_RW(idlecpus); 340 341 static int acpi_pad_add_sysfs(struct acpi_device *device) 342 { 343 int result; 344 345 result = device_create_file(&device->dev, &dev_attr_idlecpus); 346 if (result) 347 return -ENODEV; 348 result = device_create_file(&device->dev, &dev_attr_idlepct); 349 if (result) { 350 device_remove_file(&device->dev, &dev_attr_idlecpus); 351 return -ENODEV; 352 } 353 result = device_create_file(&device->dev, &dev_attr_rrtime); 354 if (result) { 355 device_remove_file(&device->dev, &dev_attr_idlecpus); 356 device_remove_file(&device->dev, &dev_attr_idlepct); 357 return -ENODEV; 358 } 359 return 0; 360 } 361 362 static void acpi_pad_remove_sysfs(struct acpi_device *device) 363 { 364 device_remove_file(&device->dev, &dev_attr_idlecpus); 365 device_remove_file(&device->dev, &dev_attr_idlepct); 366 device_remove_file(&device->dev, &dev_attr_rrtime); 367 } 368 369 /* 370 * Query firmware how many CPUs should be idle 371 * return -1 on failure 372 */ 373 static int acpi_pad_pur(acpi_handle handle) 374 { 375 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL}; 376 union acpi_object *package; 377 int num = -1; 378 379 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer))) 380 return num; 381 382 if (!buffer.length || !buffer.pointer) 383 return num; 384 385 package = buffer.pointer; 386 387 if (package->type == ACPI_TYPE_PACKAGE && 388 package->package.count == 2 && 389 package->package.elements[0].integer.value == 1) /* rev 1 */ 390 391 num = package->package.elements[1].integer.value; 392 393 kfree(buffer.pointer); 394 return num; 395 } 396 397 static void acpi_pad_handle_notify(acpi_handle handle) 398 { 399 int num_cpus; 400 uint32_t idle_cpus; 401 struct acpi_buffer param = { 402 .length = 4, 403 .pointer = (void *)&idle_cpus, 404 }; 405 406 mutex_lock(&isolated_cpus_lock); 407 num_cpus = acpi_pad_pur(handle); 408 if (num_cpus < 0) { 409 mutex_unlock(&isolated_cpus_lock); 410 return; 411 } 412 acpi_pad_idle_cpus(num_cpus); 413 idle_cpus = acpi_pad_idle_cpus_num(); 414 acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m); 415 mutex_unlock(&isolated_cpus_lock); 416 } 417 418 static void acpi_pad_notify(acpi_handle handle, u32 event, 419 void *data) 420 { 421 struct acpi_device *device = data; 422 423 switch (event) { 424 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY: 425 acpi_pad_handle_notify(handle); 426 acpi_bus_generate_netlink_event(device->pnp.device_class, 427 dev_name(&device->dev), event, 0); 428 break; 429 default: 430 pr_warn("Unsupported event [0x%x]\n", event); 431 break; 432 } 433 } 434 435 static int acpi_pad_add(struct acpi_device *device) 436 { 437 acpi_status status; 438 439 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME); 440 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS); 441 442 if (acpi_pad_add_sysfs(device)) 443 return -ENODEV; 444 445 status = acpi_install_notify_handler(device->handle, 446 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device); 447 if (ACPI_FAILURE(status)) { 448 acpi_pad_remove_sysfs(device); 449 return -ENODEV; 450 } 451 452 return 0; 453 } 454 455 static void acpi_pad_remove(struct acpi_device *device) 456 { 457 mutex_lock(&isolated_cpus_lock); 458 acpi_pad_idle_cpus(0); 459 mutex_unlock(&isolated_cpus_lock); 460 461 acpi_remove_notify_handler(device->handle, 462 ACPI_DEVICE_NOTIFY, acpi_pad_notify); 463 acpi_pad_remove_sysfs(device); 464 } 465 466 static const struct acpi_device_id pad_device_ids[] = { 467 {"ACPI000C", 0}, 468 {"", 0}, 469 }; 470 MODULE_DEVICE_TABLE(acpi, pad_device_ids); 471 472 static struct acpi_driver acpi_pad_driver = { 473 .name = "processor_aggregator", 474 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS, 475 .ids = pad_device_ids, 476 .ops = { 477 .add = acpi_pad_add, 478 .remove = acpi_pad_remove, 479 }, 480 }; 481 482 static int __init acpi_pad_init(void) 483 { 484 /* Xen ACPI PAD is used when running as Xen Dom0. */ 485 if (xen_initial_domain()) 486 return -ENODEV; 487 488 power_saving_mwait_init(); 489 if (power_saving_mwait_eax == 0) 490 return -EINVAL; 491 492 return acpi_bus_register_driver(&acpi_pad_driver); 493 } 494 495 static void __exit acpi_pad_exit(void) 496 { 497 acpi_bus_unregister_driver(&acpi_pad_driver); 498 } 499 500 module_init(acpi_pad_init); 501 module_exit(acpi_pad_exit); 502 MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>"); 503 MODULE_DESCRIPTION("ACPI Processor Aggregator Driver"); 504 MODULE_LICENSE("GPL"); 505