drivers/idle/intel_idle.c

   1 /*
   2  * intel_idle.c - native hardware idle loop for modern Intel processors
   3  *
   4  * Copyright (c) 2010, Intel Corporation.
   5  * Len Brown <len.brown@intel.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms and conditions of the GNU General Public License,
   9  * version 2, as published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  14  * more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along with
  17  * this program; if not, write to the Free Software Foundation, Inc.,
  18  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  19  */
  20
  21 /*
  22  * intel_idle is a cpuidle driver that loads on specific Intel processors
  23  * in lieu of the legacy ACPI processor_idle driver.  The intent is to
  24  * make Linux more efficient on these processors, as intel_idle knows
  25  * more than ACPI, as well as make Linux more immune to ACPI BIOS bugs.
  26  */
  27
  28 /*
  29  * Design Assumptions
  30  *
  31  * All CPUs have same idle states as boot CPU
  32  *
  33  * Chipset BM_STS (bus master status) bit is a NOP
  34  *      for preventing entry into deep C-stats
  35  */
  36
  37 /*
  38  * Known limitations
  39  *
  40  * The driver currently initializes for_each_online_cpu() upon modprobe.
  41  * It it unaware of subsequent processors hot-added to the system.
  42  * This means that if you boot with maxcpus=n and later online
  43  * processors above n, those processors will use C1 only.
  44  *
  45  * ACPI has a .suspend hack to turn off deep c-statees during suspend
  46  * to avoid complications with the lapic timer workaround.
  47  * Have not seen issues with suspend, but may need same workaround here.
  48  *
  49  * There is currently no kernel-based automatic probing/loading mechanism
  50  * if the driver is built as a module.
  51  */
  52
  53 /* un-comment DEBUG to enable pr_debug() statements */
  54 #define DEBUG
  55
  56 #include <linux/kernel.h>
  57 #include <linux/cpuidle.h>
  58 #include <linux/clockchips.h>
  59 #include <linux/hrtimer.h>      /* ktime_get_real() */
  60 #include <trace/events/power.h>
  61 #include <linux/sched.h>
  62 #include <linux/notifier.h>
  63 #include <linux/cpu.h>
  64 #include <linux/module.h>
  65 #include <asm/cpu_device_id.h>
  66 #include <asm/mwait.h>
  67 #include <asm/msr.h>
  68
  69 #define INTEL_IDLE_VERSION "0.4"
  70 #define PREFIX "intel_idle: "
  71
  72 static struct cpuidle_driver intel_idle_driver = {
  73         .name = "intel_idle",
  74         .owner = THIS_MODULE,
  75 };
  76 /* intel_idle.max_cstate=0 disables driver */
  77 static int max_cstate = MWAIT_MAX_NUM_CSTATES - 1;
  78
  79 static unsigned int mwait_substates;
  80
  81 #define LAPIC_TIMER_ALWAYS_RELIABLE 0xFFFFFFFF
  82 /* Reliable LAPIC Timer States, bit 1 for C1 etc.  */
  83 static unsigned int lapic_timer_reliable_states = (1 << 1);      /* Default to only C1 */
  84
  85 struct idle_cpu {
  86         struct cpuidle_state *state_table;
  87
  88         /*
  89          * Hardware C-state auto-demotion may not always be optimal.
  90          * Indicate which enable bits to clear here.
  91          */
  92         unsigned long auto_demotion_disable_flags;
  93 };
  94
  95 static const struct idle_cpu *icpu;
  96 static struct cpuidle_device __percpu *intel_idle_cpuidle_devices;
  97 static int intel_idle(struct cpuidle_device *dev,
  98                         struct cpuidle_driver *drv, int index);
  99
 100 static struct cpuidle_state *cpuidle_state_table;
 101
 102 /*
 103  * Set this flag for states where the HW flushes the TLB for us
 104  * and so we don't need cross-calls to keep it consistent.
 105  * If this flag is set, SW flushes the TLB, so even if the
 106  * HW doesn't do the flushing, this flag is safe to use.
 107  */
 108 #define CPUIDLE_FLAG_TLB_FLUSHED        0x10000
 109
 110 /*
 111  * States are indexed by the cstate number,
 112  * which is also the index into the MWAIT hint array.
 113  * Thus C0 is a dummy.
 114  */
 115 static struct cpuidle_state nehalem_cstates[MWAIT_MAX_NUM_CSTATES] = {
 116         { /* MWAIT C0 */ },
 117         { /* MWAIT C1 */
 118                 .name = "C1-NHM",
 119                 .desc = "MWAIT 0x00",
 120                 .flags = CPUIDLE_FLAG_TIME_VALID,
 121                 .exit_latency = 3,
 122                 .target_residency = 6,
 123                 .enter = &intel_idle },
 124         { /* MWAIT C2 */
 125                 .name = "C3-NHM",
 126                 .desc = "MWAIT 0x10",
 127                 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 128                 .exit_latency = 20,
 129                 .target_residency = 80,
 130                 .enter = &intel_idle },
 131         { /* MWAIT C3 */
 132                 .name = "C6-NHM",
 133                 .desc = "MWAIT 0x20",
 134                 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 135                 .exit_latency = 200,
 136                 .target_residency = 800,
 137                 .enter = &intel_idle },
 138 };
 139
 140 static struct cpuidle_state snb_cstates[MWAIT_MAX_NUM_CSTATES] = {
 141         { /* MWAIT C0 */ },
 142         { /* MWAIT C1 */
 143                 .name = "C1-SNB",
 144                 .desc = "MWAIT 0x00",
 145                 .flags = CPUIDLE_FLAG_TIME_VALID,
 146                 .exit_latency = 1,
 147                 .target_residency = 1,
 148                 .enter = &intel_idle },
 149         { /* MWAIT C2 */
 150                 .name = "C3-SNB",
 151                 .desc = "MWAIT 0x10",
 152                 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 153                 .exit_latency = 80,
 154                 .target_residency = 211,
 155                 .enter = &intel_idle },
 156         { /* MWAIT C3 */
 157                 .name = "C6-SNB",
 158                 .desc = "MWAIT 0x20",
 159                 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 160                 .exit_latency = 104,
 161                 .target_residency = 345,
 162                 .enter = &intel_idle },
 163         { /* MWAIT C4 */
 164                 .name = "C7-SNB",
 165                 .desc = "MWAIT 0x30",
 166                 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 167                 .exit_latency = 109,
 168                 .target_residency = 345,
 169                 .enter = &intel_idle },
 170 };
 171
 172 static struct cpuidle_state atom_cstates[MWAIT_MAX_NUM_CSTATES] = {
 173         { /* MWAIT C0 */ },
 174         { /* MWAIT C1 */
 175                 .name = "C1-ATM",
 176                 .desc = "MWAIT 0x00",
 177                 .flags = CPUIDLE_FLAG_TIME_VALID,
 178                 .exit_latency = 1,
 179                 .target_residency = 4,
 180                 .enter = &intel_idle },
 181         { /* MWAIT C2 */
 182                 .name = "C2-ATM",
 183                 .desc = "MWAIT 0x10",
 184                 .flags = CPUIDLE_FLAG_TIME_VALID,
 185                 .exit_latency = 20,
 186                 .target_residency = 80,
 187                 .enter = &intel_idle },
 188         { /* MWAIT C3 */ },
 189         { /* MWAIT C4 */
 190                 .name = "C4-ATM",
 191                 .desc = "MWAIT 0x30",
 192                 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 193                 .exit_latency = 100,
 194                 .target_residency = 400,
 195                 .enter = &intel_idle },
 196         { /* MWAIT C5 */ },
 197         { /* MWAIT C6 */
 198                 .name = "C6-ATM",
 199                 .desc = "MWAIT 0x52",
 200                 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 201                 .exit_latency = 140,
 202                 .target_residency = 560,
 203                 .enter = &intel_idle },
 204 };
 205
 206 static long get_driver_data(int cstate)
 207 {
 208         int driver_data;
 209         switch (cstate) {
 210
 211         case 1: /* MWAIT C1 */
 212                 driver_data = 0x00;
 213                 break;
 214         case 2: /* MWAIT C2 */
 215                 driver_data = 0x10;
 216                 break;
 217         case 3: /* MWAIT C3 */
 218                 driver_data = 0x20;
 219                 break;
 220         case 4: /* MWAIT C4 */
 221                 driver_data = 0x30;
 222                 break;
 223         case 5: /* MWAIT C5 */
 224                 driver_data = 0x40;
 225                 break;
 226         case 6: /* MWAIT C6 */
 227                 driver_data = 0x52;
 228                 break;
 229         default:
 230                 driver_data = 0x00;
 231         }
 232         return driver_data;
 233 }
 234
 235 /**
 236  * intel_idle
 237  * @dev: cpuidle_device
 238  * @drv: cpuidle driver
 239  * @index: index of cpuidle state
 240  *
 241  * Must be called under local_irq_disable().
 242  */
 243 static int intel_idle(struct cpuidle_device *dev,
 244                 struct cpuidle_driver *drv, int index)
 245 {
 246         unsigned long ecx = 1; /* break on interrupt flag */
 247         struct cpuidle_state *state = &drv->states[index];
 248         struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
 249         unsigned long eax = (unsigned long)cpuidle_get_statedata(state_usage);
 250         unsigned int cstate;
 251         ktime_t kt_before, kt_after;
 252         s64 usec_delta;
 253         int cpu = smp_processor_id();
 254
 255         cstate = (((eax) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) + 1;
 256
 257         /*
 258          * leave_mm() to avoid costly and often unnecessary wakeups
 259          * for flushing the user TLB's associated with the active mm.
 260          */
 261         if (state->flags & CPUIDLE_FLAG_TLB_FLUSHED)
 262                 leave_mm(cpu);
 263
 264         if (!(lapic_timer_reliable_states & (1 << (cstate))))
 265                 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
 266
 267         kt_before = ktime_get_real();
 268
 269         stop_critical_timings();
 270         if (!need_resched()) {
 271
 272                 __monitor((void *)&current_thread_info()->flags, 0, 0);
 273                 smp_mb();
 274                 if (!need_resched())
 275                         __mwait(eax, ecx);
 276         }
 277
 278         start_critical_timings();
 279
 280         kt_after = ktime_get_real();
 281         usec_delta = ktime_to_us(ktime_sub(kt_after, kt_before));
 282
 283         local_irq_enable();
 284
 285         if (!(lapic_timer_reliable_states & (1 << (cstate))))
 286                 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
 287
 288         /* Update cpuidle counters */
 289         dev->last_residency = (int)usec_delta;
 290
 291         return index;
 292 }
 293
 294 static void __setup_broadcast_timer(void *arg)
 295 {
 296         unsigned long reason = (unsigned long)arg;
 297         int cpu = smp_processor_id();
 298
 299         reason = reason ?
 300                 CLOCK_EVT_NOTIFY_BROADCAST_ON : CLOCK_EVT_NOTIFY_BROADCAST_OFF;
 301
 302         clockevents_notify(reason, &cpu);
 303 }
 304
 305 static int setup_broadcast_cpuhp_notify(struct notifier_block *n,
 306                 unsigned long action, void *hcpu)
 307 {
 308         int hotcpu = (unsigned long)hcpu;
 309
 310         switch (action & 0xf) {
 311         case CPU_ONLINE:
 312                 smp_call_function_single(hotcpu, __setup_broadcast_timer,
 313                         (void *)true, 1);
 314                 break;
 315         }
 316         return NOTIFY_OK;
 317 }
 318
 319 static struct notifier_block setup_broadcast_notifier = {
 320         .notifier_call = setup_broadcast_cpuhp_notify,
 321 };
 322
 323 static void auto_demotion_disable(void *dummy)
 324 {
 325         unsigned long long msr_bits;
 326
 327         rdmsrl(MSR_NHM_SNB_PKG_CST_CFG_CTL, msr_bits);
 328         msr_bits &= ~(icpu->auto_demotion_disable_flags);
 329         wrmsrl(MSR_NHM_SNB_PKG_CST_CFG_CTL, msr_bits);
 330 }
 331
 332 static const struct idle_cpu idle_cpu_nehalem = {
 333         .state_table = nehalem_cstates,
 334         .auto_demotion_disable_flags = NHM_C1_AUTO_DEMOTE | NHM_C3_AUTO_DEMOTE,
 335 };
 336
 337 static const struct idle_cpu idle_cpu_atom = {
 338         .state_table = atom_cstates,
 339 };
 340
 341 static const struct idle_cpu idle_cpu_lincroft = {
 342         .state_table = atom_cstates,
 343         .auto_demotion_disable_flags = ATM_LNC_C6_AUTO_DEMOTE,
 344 };
 345
 346 static const struct idle_cpu idle_cpu_snb = {
 347         .state_table = snb_cstates,
 348 };
 349
 350 #define ICPU(model, cpu) \
 351         { X86_VENDOR_INTEL, 6, model, X86_FEATURE_MWAIT, (unsigned long)&cpu }
 352
 353 static const struct x86_cpu_id intel_idle_ids[] = {
 354         ICPU(0x1a, idle_cpu_nehalem),
 355         ICPU(0x1e, idle_cpu_nehalem),
 356         ICPU(0x1f, idle_cpu_nehalem),
 357         ICPU(0x25, idle_cpu_nehalem),
 358         ICPU(0x2c, idle_cpu_nehalem),
 359         ICPU(0x2e, idle_cpu_nehalem),
 360         ICPU(0x1c, idle_cpu_atom),
 361         ICPU(0x26, idle_cpu_lincroft),
 362         ICPU(0x2f, idle_cpu_nehalem),
 363         ICPU(0x2a, idle_cpu_snb),
 364         ICPU(0x2d, idle_cpu_snb),
 365         {}
 366 };
 367 MODULE_DEVICE_TABLE(x86cpu, intel_idle_ids);
 368
 369 /*
 370  * intel_idle_probe()
 371  */
 372 static int intel_idle_probe(void)
 373 {
 374         unsigned int eax, ebx, ecx;
 375         const struct x86_cpu_id *id;
 376
 377         if (max_cstate == 0) {
 378                 pr_debug(PREFIX "disabled\n");
 379                 return -EPERM;
 380         }
 381
 382         id = x86_match_cpu(intel_idle_ids);
 383         if (!id) {
 384                 if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
 385                     boot_cpu_data.x86 == 6)
 386                         pr_debug(PREFIX "does not run on family %d model %d\n",
 387                                 boot_cpu_data.x86, boot_cpu_data.x86_model);
 388                 return -ENODEV;
 389         }
 390
 391         if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
 392                 return -ENODEV;
 393
 394         cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates);
 395
 396         if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
 397             !(ecx & CPUID5_ECX_INTERRUPT_BREAK) ||
 398             !mwait_substates)
 399                         return -ENODEV;
 400
 401         pr_debug(PREFIX "MWAIT substates: 0x%x\n", mwait_substates);
 402
 403         icpu = (const struct idle_cpu *)id->driver_data;
 404         cpuidle_state_table = icpu->state_table;
 405
 406         if (boot_cpu_has(X86_FEATURE_ARAT))     /* Always Reliable APIC Timer */
 407                 lapic_timer_reliable_states = LAPIC_TIMER_ALWAYS_RELIABLE;
 408         else {
 409                 on_each_cpu(__setup_broadcast_timer, (void *)true, 1);
 410                 register_cpu_notifier(&setup_broadcast_notifier);
 411         }
 412
 413         pr_debug(PREFIX "v" INTEL_IDLE_VERSION
 414                 " model 0x%X\n", boot_cpu_data.x86_model);
 415
 416         pr_debug(PREFIX "lapic_timer_reliable_states 0x%x\n",
 417                 lapic_timer_reliable_states);
 418         return 0;
 419 }
 420
 421 /*
 422  * intel_idle_cpuidle_devices_uninit()
 423  * unregister, free cpuidle_devices
 424  */
 425 static void intel_idle_cpuidle_devices_uninit(void)
 426 {
 427         int i;
 428         struct cpuidle_device *dev;
 429
 430         for_each_online_cpu(i) {
 431                 dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
 432                 cpuidle_unregister_device(dev);
 433         }
 434
 435         free_percpu(intel_idle_cpuidle_devices);
 436         return;
 437 }
 438 /*
 439  * intel_idle_cpuidle_driver_init()
 440  * allocate, initialize cpuidle_states
 441  */
 442 static int intel_idle_cpuidle_driver_init(void)
 443 {
 444         int cstate;
 445         struct cpuidle_driver *drv = &intel_idle_driver;
 446
 447         drv->state_count = 1;
 448
 449         for (cstate = 1; cstate < MWAIT_MAX_NUM_CSTATES; ++cstate) {
 450                 int num_substates;
 451
 452                 if (cstate > max_cstate) {
 453                         printk(PREFIX "max_cstate %d reached\n",
 454                                 max_cstate);
 455                         break;
 456                 }
 457
 458                 /* does the state exist in CPUID.MWAIT? */
 459                 num_substates = (mwait_substates >> ((cstate) * 4))
 460                                         & MWAIT_SUBSTATE_MASK;
 461                 if (num_substates == 0)
 462                         continue;
 463                 /* is the state not enabled? */
 464                 if (cpuidle_state_table[cstate].enter == NULL) {
 465                         /* does the driver not know about the state? */
 466                         if (*cpuidle_state_table[cstate].name == '\0')
 467                                 pr_debug(PREFIX "unaware of model 0x%x"
 468                                         " MWAIT %d please"
 469                                         " contact lenb@kernel.org",
 470                                 boot_cpu_data.x86_model, cstate);
 471                         continue;
 472                 }
 473
 474                 if ((cstate > 2) &&
 475                         !boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
 476                         mark_tsc_unstable("TSC halts in idle"
 477                                         " states deeper than C2");
 478
 479                 drv->states[drv->state_count] = /* structure copy */
 480                         cpuidle_state_table[cstate];
 481
 482                 drv->state_count += 1;
 483         }
 484
 485         if (icpu->auto_demotion_disable_flags)
 486                 on_each_cpu(auto_demotion_disable, NULL, 1);
 487
 488         return 0;
 489 }
 490
 491
 492 /*
 493  * intel_idle_cpu_init()
 494  * allocate, initialize, register cpuidle_devices
 495  * @cpu: cpu/core to initialize
 496  */
 497 int intel_idle_cpu_init(int cpu)
 498 {
 499         int cstate;
 500         struct cpuidle_device *dev;
 501
 502         dev = per_cpu_ptr(intel_idle_cpuidle_devices, cpu);
 503
 504         dev->state_count = 1;
 505
 506         for (cstate = 1; cstate < MWAIT_MAX_NUM_CSTATES; ++cstate) {
 507                 int num_substates;
 508
 509                 if (cstate > max_cstate) {
 510                         printk(PREFIX "max_cstate %d reached\n",
 511                                max_cstate);
 512                         break;
 513                 }
 514
 515                 /* does the state exist in CPUID.MWAIT? */
 516                 num_substates = (mwait_substates >> ((cstate) * 4))
 517                         & MWAIT_SUBSTATE_MASK;
 518                 if (num_substates == 0)
 519                         continue;
 520                 /* is the state not enabled? */
 521                 if (cpuidle_state_table[cstate].enter == NULL)
 522                         continue;
 523
 524                 dev->states_usage[dev->state_count].driver_data =
 525                         (void *)get_driver_data(cstate);
 526
 527                         dev->state_count += 1;
 528                 }
 529         dev->cpu = cpu;
 530
 531         if (cpuidle_register_device(dev)) {
 532                 pr_debug(PREFIX "cpuidle_register_device %d failed!\n", cpu);
 533                 intel_idle_cpuidle_devices_uninit();
 534                 return -EIO;
 535         }
 536
 537         if (icpu->auto_demotion_disable_flags)
 538                 smp_call_function_single(cpu, auto_demotion_disable, NULL, 1);
 539
 540         return 0;
 541 }
 542 EXPORT_SYMBOL_GPL(intel_idle_cpu_init);
 543
 544 static int __init intel_idle_init(void)
 545 {
 546         int retval, i;
 547
 548         /* Do not load intel_idle at all for now if idle= is passed */
 549         if (boot_option_idle_override != IDLE_NO_OVERRIDE)
 550                 return -ENODEV;
 551
 552         retval = intel_idle_probe();
 553         if (retval)
 554                 return retval;
 555
 556         intel_idle_cpuidle_driver_init();
 557         retval = cpuidle_register_driver(&intel_idle_driver);
 558         if (retval) {
 559                 printk(KERN_DEBUG PREFIX "intel_idle yielding to %s",
 560                         cpuidle_get_driver()->name);
 561                 return retval;
 562         }
 563
 564         intel_idle_cpuidle_devices = alloc_percpu(struct cpuidle_device);
 565         if (intel_idle_cpuidle_devices == NULL)
 566                 return -ENOMEM;
 567
 568         for_each_online_cpu(i) {
 569                 retval = intel_idle_cpu_init(i);
 570                 if (retval) {
 571                         cpuidle_unregister_driver(&intel_idle_driver);
 572                         return retval;
 573                 }
 574         }
 575
 576         return 0;
 577 }
 578
 579 static void __exit intel_idle_exit(void)
 580 {
 581         intel_idle_cpuidle_devices_uninit();
 582         cpuidle_unregister_driver(&intel_idle_driver);
 583
 584         if (lapic_timer_reliable_states != LAPIC_TIMER_ALWAYS_RELIABLE) {
 585                 on_each_cpu(__setup_broadcast_timer, (void *)false, 1);
 586                 unregister_cpu_notifier(&setup_broadcast_notifier);
 587         }
 588
 589         return;
 590 }
 591
 592 module_init(intel_idle_init);
 593 module_exit(intel_idle_exit);
 594
 595 module_param(max_cstate, int, 0444);
 596
 597 MODULE_AUTHOR("Len Brown <len.brown@intel.com>");
 598 MODULE_DESCRIPTION("Cpuidle driver for Intel Hardware v" INTEL_IDLE_VERSION);
 599 MODULE_LICENSE("GPL");