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