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 static int intel_idle_cpu_init(int cpu);
 100
 101 static struct cpuidle_state *cpuidle_state_table;
 102
 103 /*
 104  * Set this flag for states where the HW flushes the TLB for us
 105  * and so we don't need cross-calls to keep it consistent.
 106  * If this flag is set, SW flushes the TLB, so even if the
 107  * HW doesn't do the flushing, this flag is safe to use.
 108  */
 109 #define CPUIDLE_FLAG_TLB_FLUSHED        0x10000
 110
 111 /*
 112  * States are indexed by the cstate number,
 113  * which is also the index into the MWAIT hint array.
 114  * Thus C0 is a dummy.
 115  */
 116 static struct cpuidle_state nehalem_cstates[MWAIT_MAX_NUM_CSTATES] = {
 117         { /* MWAIT C0 */ },
 118         { /* MWAIT C1 */
 119                 .name = "C1-NHM",
 120                 .desc = "MWAIT 0x00",
 121                 .flags = CPUIDLE_FLAG_TIME_VALID,
 122                 .exit_latency = 3,
 123                 .target_residency = 6,
 124                 .enter = &intel_idle },
 125         { /* MWAIT C2 */
 126                 .name = "C3-NHM",
 127                 .desc = "MWAIT 0x10",
 128                 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 129                 .exit_latency = 20,
 130                 .target_residency = 80,
 131                 .enter = &intel_idle },
 132         { /* MWAIT C3 */
 133                 .name = "C6-NHM",
 134                 .desc = "MWAIT 0x20",
 135                 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 136                 .exit_latency = 200,
 137                 .target_residency = 800,
 138                 .enter = &intel_idle },
 139 };
 140
 141 static struct cpuidle_state snb_cstates[MWAIT_MAX_NUM_CSTATES] = {
 142         { /* MWAIT C0 */ },
 143         { /* MWAIT C1 */
 144                 .name = "C1-SNB",
 145                 .desc = "MWAIT 0x00",
 146                 .flags = CPUIDLE_FLAG_TIME_VALID,
 147                 .exit_latency = 1,
 148                 .target_residency = 1,
 149                 .enter = &intel_idle },
 150         { /* MWAIT C2 */
 151                 .name = "C3-SNB",
 152                 .desc = "MWAIT 0x10",
 153                 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 154                 .exit_latency = 80,
 155                 .target_residency = 211,
 156                 .enter = &intel_idle },
 157         { /* MWAIT C3 */
 158                 .name = "C6-SNB",
 159                 .desc = "MWAIT 0x20",
 160                 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 161                 .exit_latency = 104,
 162                 .target_residency = 345,
 163                 .enter = &intel_idle },
 164         { /* MWAIT C4 */
 165                 .name = "C7-SNB",
 166                 .desc = "MWAIT 0x30",
 167                 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 168                 .exit_latency = 109,
 169                 .target_residency = 345,
 170                 .enter = &intel_idle },
 171 };
 172
 173 static struct cpuidle_state atom_cstates[MWAIT_MAX_NUM_CSTATES] = {
 174         { /* MWAIT C0 */ },
 175         { /* MWAIT C1 */
 176                 .name = "C1-ATM",
 177                 .desc = "MWAIT 0x00",
 178                 .flags = CPUIDLE_FLAG_TIME_VALID,
 179                 .exit_latency = 1,
 180                 .target_residency = 4,
 181                 .enter = &intel_idle },
 182         { /* MWAIT C2 */
 183                 .name = "C2-ATM",
 184                 .desc = "MWAIT 0x10",
 185                 .flags = CPUIDLE_FLAG_TIME_VALID,
 186                 .exit_latency = 20,
 187                 .target_residency = 80,
 188                 .enter = &intel_idle },
 189         { /* MWAIT C3 */ },
 190         { /* MWAIT C4 */
 191                 .name = "C4-ATM",
 192                 .desc = "MWAIT 0x30",
 193                 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 194                 .exit_latency = 100,
 195                 .target_residency = 400,
 196                 .enter = &intel_idle },
 197         { /* MWAIT C5 */ },
 198         { /* MWAIT C6 */
 199                 .name = "C6-ATM",
 200                 .desc = "MWAIT 0x52",
 201                 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 202                 .exit_latency = 140,
 203                 .target_residency = 560,
 204                 .enter = &intel_idle },
 205 };
 206
 207 static long get_driver_data(int cstate)
 208 {
 209         int driver_data;
 210         switch (cstate) {
 211
 212         case 1: /* MWAIT C1 */
 213                 driver_data = 0x00;
 214                 break;
 215         case 2: /* MWAIT C2 */
 216                 driver_data = 0x10;
 217                 break;
 218         case 3: /* MWAIT C3 */
 219                 driver_data = 0x20;
 220                 break;
 221         case 4: /* MWAIT C4 */
 222                 driver_data = 0x30;
 223                 break;
 224         case 5: /* MWAIT C5 */
 225                 driver_data = 0x40;
 226                 break;
 227         case 6: /* MWAIT C6 */
 228                 driver_data = 0x52;
 229                 break;
 230         default:
 231                 driver_data = 0x00;
 232         }
 233         return driver_data;
 234 }
 235
 236 /**
 237  * intel_idle
 238  * @dev: cpuidle_device
 239  * @drv: cpuidle driver
 240  * @index: index of cpuidle state
 241  *
 242  * Must be called under local_irq_disable().
 243  */
 244 static int intel_idle(struct cpuidle_device *dev,
 245                 struct cpuidle_driver *drv, int index)
 246 {
 247         unsigned long ecx = 1; /* break on interrupt flag */
 248         struct cpuidle_state *state = &drv->states[index];
 249         struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
 250         unsigned long eax = (unsigned long)cpuidle_get_statedata(state_usage);
 251         unsigned int cstate;
 252         ktime_t kt_before, kt_after;
 253         s64 usec_delta;
 254         int cpu = smp_processor_id();
 255
 256         cstate = (((eax) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) + 1;
 257
 258         /*
 259          * leave_mm() to avoid costly and often unnecessary wakeups
 260          * for flushing the user TLB's associated with the active mm.
 261          */
 262         if (state->flags & CPUIDLE_FLAG_TLB_FLUSHED)
 263                 leave_mm(cpu);
 264
 265         if (!(lapic_timer_reliable_states & (1 << (cstate))))
 266                 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
 267
 268         kt_before = ktime_get_real();
 269
 270         stop_critical_timings();
 271         if (!need_resched()) {
 272
 273                 __monitor((void *)&current_thread_info()->flags, 0, 0);
 274                 smp_mb();
 275                 if (!need_resched())
 276                         __mwait(eax, ecx);
 277         }
 278
 279         start_critical_timings();
 280
 281         kt_after = ktime_get_real();
 282         usec_delta = ktime_to_us(ktime_sub(kt_after, kt_before));
 283
 284         local_irq_enable();
 285
 286         if (!(lapic_timer_reliable_states & (1 << (cstate))))
 287                 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
 288
 289         /* Update cpuidle counters */
 290         dev->last_residency = (int)usec_delta;
 291
 292         return index;
 293 }
 294
 295 static void __setup_broadcast_timer(void *arg)
 296 {
 297         unsigned long reason = (unsigned long)arg;
 298         int cpu = smp_processor_id();
 299
 300         reason = reason ?
 301                 CLOCK_EVT_NOTIFY_BROADCAST_ON : CLOCK_EVT_NOTIFY_BROADCAST_OFF;
 302
 303         clockevents_notify(reason, &cpu);
 304 }
 305
 306 static int cpu_hotplug_notify(struct notifier_block *n,
 307                               unsigned long action, void *hcpu)
 308 {
 309         int hotcpu = (unsigned long)hcpu;
 310         struct cpuidle_device *dev;
 311
 312         switch (action & 0xf) {
 313         case CPU_ONLINE:
 314
 315                 if (lapic_timer_reliable_states != LAPIC_TIMER_ALWAYS_RELIABLE)
 316                         smp_call_function_single(hotcpu, __setup_broadcast_timer,
 317                                                  (void *)true, 1);
 318
 319                 /*
 320                  * Some systems can hotplug a cpu at runtime after
 321                  * the kernel has booted, we have to initialize the
 322                  * driver in this case
 323                  */
 324                 dev = per_cpu_ptr(intel_idle_cpuidle_devices, hotcpu);
 325                 if (!dev->registered)
 326                         intel_idle_cpu_init(hotcpu);
 327
 328                 break;
 329         }
 330         return NOTIFY_OK;
 331 }
 332
 333 static struct notifier_block cpu_hotplug_notifier = {
 334         .notifier_call = cpu_hotplug_notify,
 335 };
 336
 337 static void auto_demotion_disable(void *dummy)
 338 {
 339         unsigned long long msr_bits;
 340
 341         rdmsrl(MSR_NHM_SNB_PKG_CST_CFG_CTL, msr_bits);
 342         msr_bits &= ~(icpu->auto_demotion_disable_flags);
 343         wrmsrl(MSR_NHM_SNB_PKG_CST_CFG_CTL, msr_bits);
 344 }
 345
 346 static const struct idle_cpu idle_cpu_nehalem = {
 347         .state_table = nehalem_cstates,
 348         .auto_demotion_disable_flags = NHM_C1_AUTO_DEMOTE | NHM_C3_AUTO_DEMOTE,
 349 };
 350
 351 static const struct idle_cpu idle_cpu_atom = {
 352         .state_table = atom_cstates,
 353 };
 354
 355 static const struct idle_cpu idle_cpu_lincroft = {
 356         .state_table = atom_cstates,
 357         .auto_demotion_disable_flags = ATM_LNC_C6_AUTO_DEMOTE,
 358 };
 359
 360 static const struct idle_cpu idle_cpu_snb = {
 361         .state_table = snb_cstates,
 362 };
 363
 364 #define ICPU(model, cpu) \
 365         { X86_VENDOR_INTEL, 6, model, X86_FEATURE_MWAIT, (unsigned long)&cpu }
 366
 367 static const struct x86_cpu_id intel_idle_ids[] = {
 368         ICPU(0x1a, idle_cpu_nehalem),
 369         ICPU(0x1e, idle_cpu_nehalem),
 370         ICPU(0x1f, idle_cpu_nehalem),
 371         ICPU(0x25, idle_cpu_nehalem),
 372         ICPU(0x2c, idle_cpu_nehalem),
 373         ICPU(0x2e, idle_cpu_nehalem),
 374         ICPU(0x1c, idle_cpu_atom),
 375         ICPU(0x26, idle_cpu_lincroft),
 376         ICPU(0x2f, idle_cpu_nehalem),
 377         ICPU(0x2a, idle_cpu_snb),
 378         ICPU(0x2d, idle_cpu_snb),
 379         {}
 380 };
 381 MODULE_DEVICE_TABLE(x86cpu, intel_idle_ids);
 382
 383 /*
 384  * intel_idle_probe()
 385  */
 386 static int intel_idle_probe(void)
 387 {
 388         unsigned int eax, ebx, ecx;
 389         const struct x86_cpu_id *id;
 390
 391         if (max_cstate == 0) {
 392                 pr_debug(PREFIX "disabled\n");
 393                 return -EPERM;
 394         }
 395
 396         id = x86_match_cpu(intel_idle_ids);
 397         if (!id) {
 398                 if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
 399                     boot_cpu_data.x86 == 6)
 400                         pr_debug(PREFIX "does not run on family %d model %d\n",
 401                                 boot_cpu_data.x86, boot_cpu_data.x86_model);
 402                 return -ENODEV;
 403         }
 404
 405         if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
 406                 return -ENODEV;
 407
 408         cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates);
 409
 410         if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
 411             !(ecx & CPUID5_ECX_INTERRUPT_BREAK) ||
 412             !mwait_substates)
 413                         return -ENODEV;
 414
 415         pr_debug(PREFIX "MWAIT substates: 0x%x\n", mwait_substates);
 416
 417         icpu = (const struct idle_cpu *)id->driver_data;
 418         cpuidle_state_table = icpu->state_table;
 419
 420         if (boot_cpu_has(X86_FEATURE_ARAT))     /* Always Reliable APIC Timer */
 421                 lapic_timer_reliable_states = LAPIC_TIMER_ALWAYS_RELIABLE;
 422         else
 423                 on_each_cpu(__setup_broadcast_timer, (void *)true, 1);
 424
 425         register_cpu_notifier(&cpu_hotplug_notifier);
 426
 427         pr_debug(PREFIX "v" INTEL_IDLE_VERSION
 428                 " model 0x%X\n", boot_cpu_data.x86_model);
 429
 430         pr_debug(PREFIX "lapic_timer_reliable_states 0x%x\n",
 431                 lapic_timer_reliable_states);
 432         return 0;
 433 }
 434
 435 /*
 436  * intel_idle_cpuidle_devices_uninit()
 437  * unregister, free cpuidle_devices
 438  */
 439 static void intel_idle_cpuidle_devices_uninit(void)
 440 {
 441         int i;
 442         struct cpuidle_device *dev;
 443
 444         for_each_online_cpu(i) {
 445                 dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
 446                 cpuidle_unregister_device(dev);
 447         }
 448
 449         free_percpu(intel_idle_cpuidle_devices);
 450         return;
 451 }
 452 /*
 453  * intel_idle_cpuidle_driver_init()
 454  * allocate, initialize cpuidle_states
 455  */
 456 static int intel_idle_cpuidle_driver_init(void)
 457 {
 458         int cstate;
 459         struct cpuidle_driver *drv = &intel_idle_driver;
 460
 461         drv->state_count = 1;
 462
 463         for (cstate = 1; cstate < MWAIT_MAX_NUM_CSTATES; ++cstate) {
 464                 int num_substates;
 465
 466                 if (cstate > max_cstate) {
 467                         printk(PREFIX "max_cstate %d reached\n",
 468                                 max_cstate);
 469                         break;
 470                 }
 471
 472                 /* does the state exist in CPUID.MWAIT? */
 473                 num_substates = (mwait_substates >> ((cstate) * 4))
 474                                         & MWAIT_SUBSTATE_MASK;
 475                 if (num_substates == 0)
 476                         continue;
 477                 /* is the state not enabled? */
 478                 if (cpuidle_state_table[cstate].enter == NULL) {
 479                         /* does the driver not know about the state? */
 480                         if (*cpuidle_state_table[cstate].name == '\0')
 481                                 pr_debug(PREFIX "unaware of model 0x%x"
 482                                         " MWAIT %d please"
 483                                         " contact lenb@kernel.org",
 484                                 boot_cpu_data.x86_model, cstate);
 485                         continue;
 486                 }
 487
 488                 if ((cstate > 2) &&
 489                         !boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
 490                         mark_tsc_unstable("TSC halts in idle"
 491                                         " states deeper than C2");
 492
 493                 drv->states[drv->state_count] = /* structure copy */
 494                         cpuidle_state_table[cstate];
 495
 496                 drv->state_count += 1;
 497         }
 498
 499         if (icpu->auto_demotion_disable_flags)
 500                 on_each_cpu(auto_demotion_disable, NULL, 1);
 501
 502         return 0;
 503 }
 504
 505
 506 /*
 507  * intel_idle_cpu_init()
 508  * allocate, initialize, register cpuidle_devices
 509  * @cpu: cpu/core to initialize
 510  */
 511 static int intel_idle_cpu_init(int cpu)
 512 {
 513         int cstate;
 514         struct cpuidle_device *dev;
 515
 516         dev = per_cpu_ptr(intel_idle_cpuidle_devices, cpu);
 517
 518         dev->state_count = 1;
 519
 520         for (cstate = 1; cstate < MWAIT_MAX_NUM_CSTATES; ++cstate) {
 521                 int num_substates;
 522
 523                 if (cstate > max_cstate) {
 524                         printk(PREFIX "max_cstate %d reached\n", max_cstate);
 525                         break;
 526                 }
 527
 528                 /* does the state exist in CPUID.MWAIT? */
 529                 num_substates = (mwait_substates >> ((cstate) * 4))
 530                         & MWAIT_SUBSTATE_MASK;
 531                 if (num_substates == 0)
 532                         continue;
 533                 /* is the state not enabled? */
 534                 if (cpuidle_state_table[cstate].enter == NULL)
 535                         continue;
 536
 537                 dev->states_usage[dev->state_count].driver_data =
 538                         (void *)get_driver_data(cstate);
 539
 540                 dev->state_count += 1;
 541         }
 542
 543         dev->cpu = cpu;
 544
 545         if (cpuidle_register_device(dev)) {
 546                 pr_debug(PREFIX "cpuidle_register_device %d failed!\n", cpu);
 547                 intel_idle_cpuidle_devices_uninit();
 548                 return -EIO;
 549         }
 550
 551         if (icpu->auto_demotion_disable_flags)
 552                 smp_call_function_single(cpu, auto_demotion_disable, NULL, 1);
 553
 554         return 0;
 555 }
 556
 557 static int __init intel_idle_init(void)
 558 {
 559         int retval, i;
 560
 561         /* Do not load intel_idle at all for now if idle= is passed */
 562         if (boot_option_idle_override != IDLE_NO_OVERRIDE)
 563                 return -ENODEV;
 564
 565         retval = intel_idle_probe();
 566         if (retval)
 567                 return retval;
 568
 569         intel_idle_cpuidle_driver_init();
 570         retval = cpuidle_register_driver(&intel_idle_driver);
 571         if (retval) {
 572                 printk(KERN_DEBUG PREFIX "intel_idle yielding to %s",
 573                         cpuidle_get_driver()->name);
 574                 return retval;
 575         }
 576
 577         intel_idle_cpuidle_devices = alloc_percpu(struct cpuidle_device);
 578         if (intel_idle_cpuidle_devices == NULL)
 579                 return -ENOMEM;
 580
 581         for_each_online_cpu(i) {
 582                 retval = intel_idle_cpu_init(i);
 583                 if (retval) {
 584                         cpuidle_unregister_driver(&intel_idle_driver);
 585                         return retval;
 586                 }
 587         }
 588
 589         return 0;
 590 }
 591
 592 static void __exit intel_idle_exit(void)
 593 {
 594         intel_idle_cpuidle_devices_uninit();
 595         cpuidle_unregister_driver(&intel_idle_driver);
 596
 597
 598         if (lapic_timer_reliable_states != LAPIC_TIMER_ALWAYS_RELIABLE)
 599                 on_each_cpu(__setup_broadcast_timer, (void *)false, 1);
 600         unregister_cpu_notifier(&cpu_hotplug_notifier);
 601
 602         return;
 603 }
 604
 605 module_init(intel_idle_init);
 606 module_exit(intel_idle_exit);
 607
 608 module_param(max_cstate, int, 0444);
 609
 610 MODULE_AUTHOR("Len Brown <len.brown@intel.com>");
 611 MODULE_DESCRIPTION("Cpuidle driver for Intel Hardware v" INTEL_IDLE_VERSION);
 612 MODULE_LICENSE("GPL");