arch/x86/kvm/i8254.c

   1 /*
   2  * 8253/8254 interval timer emulation
   3  *
   4  * Copyright (c) 2003-2004 Fabrice Bellard
   5  * Copyright (c) 2006 Intel Corporation
   6  * Copyright (c) 2007 Keir Fraser, XenSource Inc
   7  * Copyright (c) 2008 Intel Corporation
   8  * Copyright 2009 Red Hat, Inc. and/or its affiliates.
   9  *
  10  * Permission is hereby granted, free of charge, to any person obtaining a copy
  11  * of this software and associated documentation files (the "Software"), to deal
  12  * in the Software without restriction, including without limitation the rights
  13  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  14  * copies of the Software, and to permit persons to whom the Software is
  15  * furnished to do so, subject to the following conditions:
  16  *
  17  * The above copyright notice and this permission notice shall be included in
  18  * all copies or substantial portions of the Software.
  19  *
  20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  23  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  24  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  25  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  26  * THE SOFTWARE.
  27  *
  28  * Authors:
  29  *   Sheng Yang <sheng.yang@intel.com>
  30  *   Based on QEMU and Xen.
  31  */
  32
  33 #define pr_fmt(fmt) "pit: " fmt
  34
  35 #include <linux/kvm_host.h>
  36 #include <linux/slab.h>
  37
  38 #include "ioapic.h"
  39 #include "irq.h"
  40 #include "i8254.h"
  41 #include "x86.h"
  42
  43 #ifndef CONFIG_X86_64
  44 #define mod_64(x, y) ((x) - (y) * div64_u64(x, y))
  45 #else
  46 #define mod_64(x, y) ((x) % (y))
  47 #endif
  48
  49 #define RW_STATE_LSB 1
  50 #define RW_STATE_MSB 2
  51 #define RW_STATE_WORD0 3
  52 #define RW_STATE_WORD1 4
  53
  54 static void pit_set_gate(struct kvm_pit *pit, int channel, u32 val)
  55 {
  56         struct kvm_kpit_channel_state *c = &pit->pit_state.channels[channel];
  57
  58         switch (c->mode) {
  59         default:
  60         case 0:
  61         case 4:
  62                 /* XXX: just disable/enable counting */
  63                 break;
  64         case 1:
  65         case 2:
  66         case 3:
  67         case 5:
  68                 /* Restart counting on rising edge. */
  69                 if (c->gate < val)
  70                         c->count_load_time = ktime_get();
  71                 break;
  72         }
  73
  74         c->gate = val;
  75 }
  76
  77 static int pit_get_gate(struct kvm_pit *pit, int channel)
  78 {
  79         return pit->pit_state.channels[channel].gate;
  80 }
  81
  82 static s64 __kpit_elapsed(struct kvm_pit *pit)
  83 {
  84         s64 elapsed;
  85         ktime_t remaining;
  86         struct kvm_kpit_state *ps = &pit->pit_state;
  87
  88         if (!ps->period)
  89                 return 0;
  90
  91         /*
  92          * The Counter does not stop when it reaches zero. In
  93          * Modes 0, 1, 4, and 5 the Counter ``wraps around'' to
  94          * the highest count, either FFFF hex for binary counting
  95          * or 9999 for BCD counting, and continues counting.
  96          * Modes 2 and 3 are periodic; the Counter reloads
  97          * itself with the initial count and continues counting
  98          * from there.
  99          */
 100         remaining = hrtimer_get_remaining(&ps->timer);
 101         elapsed = ps->period - ktime_to_ns(remaining);
 102
 103         return elapsed;
 104 }
 105
 106 static s64 kpit_elapsed(struct kvm_pit *pit, struct kvm_kpit_channel_state *c,
 107                         int channel)
 108 {
 109         if (channel == 0)
 110                 return __kpit_elapsed(pit);
 111
 112         return ktime_to_ns(ktime_sub(ktime_get(), c->count_load_time));
 113 }
 114
 115 static int pit_get_count(struct kvm_pit *pit, int channel)
 116 {
 117         struct kvm_kpit_channel_state *c = &pit->pit_state.channels[channel];
 118         s64 d, t;
 119         int counter;
 120
 121         t = kpit_elapsed(pit, c, channel);
 122         d = mul_u64_u32_div(t, KVM_PIT_FREQ, NSEC_PER_SEC);
 123
 124         switch (c->mode) {
 125         case 0:
 126         case 1:
 127         case 4:
 128         case 5:
 129                 counter = (c->count - d) & 0xffff;
 130                 break;
 131         case 3:
 132                 /* XXX: may be incorrect for odd counts */
 133                 counter = c->count - (mod_64((2 * d), c->count));
 134                 break;
 135         default:
 136                 counter = c->count - mod_64(d, c->count);
 137                 break;
 138         }
 139         return counter;
 140 }
 141
 142 static int pit_get_out(struct kvm_pit *pit, int channel)
 143 {
 144         struct kvm_kpit_channel_state *c = &pit->pit_state.channels[channel];
 145         s64 d, t;
 146         int out;
 147
 148         t = kpit_elapsed(pit, c, channel);
 149         d = mul_u64_u32_div(t, KVM_PIT_FREQ, NSEC_PER_SEC);
 150
 151         switch (c->mode) {
 152         default:
 153         case 0:
 154                 out = (d >= c->count);
 155                 break;
 156         case 1:
 157                 out = (d < c->count);
 158                 break;
 159         case 2:
 160                 out = ((mod_64(d, c->count) == 0) && (d != 0));
 161                 break;
 162         case 3:
 163                 out = (mod_64(d, c->count) < ((c->count + 1) >> 1));
 164                 break;
 165         case 4:
 166         case 5:
 167                 out = (d == c->count);
 168                 break;
 169         }
 170
 171         return out;
 172 }
 173
 174 static void pit_latch_count(struct kvm_pit *pit, int channel)
 175 {
 176         struct kvm_kpit_channel_state *c = &pit->pit_state.channels[channel];
 177
 178         if (!c->count_latched) {
 179                 c->latched_count = pit_get_count(pit, channel);
 180                 c->count_latched = c->rw_mode;
 181         }
 182 }
 183
 184 static void pit_latch_status(struct kvm_pit *pit, int channel)
 185 {
 186         struct kvm_kpit_channel_state *c = &pit->pit_state.channels[channel];
 187
 188         if (!c->status_latched) {
 189                 /* TODO: Return NULL COUNT (bit 6). */
 190                 c->status = ((pit_get_out(pit, channel) << 7) |
 191                                 (c->rw_mode << 4) |
 192                                 (c->mode << 1) |
 193                                 c->bcd);
 194                 c->status_latched = 1;
 195         }
 196 }
 197
 198 static inline struct kvm_pit *pit_state_to_pit(struct kvm_kpit_state *ps)
 199 {
 200         return container_of(ps, struct kvm_pit, pit_state);
 201 }
 202
 203 static void kvm_pit_ack_irq(struct kvm_irq_ack_notifier *kian)
 204 {
 205         struct kvm_kpit_state *ps = container_of(kian, struct kvm_kpit_state,
 206                                                  irq_ack_notifier);
 207         struct kvm_pit *pit = pit_state_to_pit(ps);
 208
 209         atomic_set(&ps->irq_ack, 1);
 210         /* irq_ack should be set before pending is read.  Order accesses with
 211          * inc(pending) in pit_timer_fn and xchg(irq_ack, 0) in pit_do_work.
 212          */
 213         smp_mb();
 214         if (atomic_dec_if_positive(&ps->pending) > 0)
 215                 queue_kthread_work(&pit->worker, &pit->expired);
 216 }
 217
 218 void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu)
 219 {
 220         struct kvm_pit *pit = vcpu->kvm->arch.vpit;
 221         struct hrtimer *timer;
 222
 223         if (!kvm_vcpu_is_bsp(vcpu) || !pit)
 224                 return;
 225
 226         timer = &pit->pit_state.timer;
 227         mutex_lock(&pit->pit_state.lock);
 228         if (hrtimer_cancel(timer))
 229                 hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 230         mutex_unlock(&pit->pit_state.lock);
 231 }
 232
 233 static void destroy_pit_timer(struct kvm_pit *pit)
 234 {
 235         hrtimer_cancel(&pit->pit_state.timer);
 236         flush_kthread_work(&pit->expired);
 237 }
 238
 239 static void pit_do_work(struct kthread_work *work)
 240 {
 241         struct kvm_pit *pit = container_of(work, struct kvm_pit, expired);
 242         struct kvm *kvm = pit->kvm;
 243         struct kvm_vcpu *vcpu;
 244         int i;
 245         struct kvm_kpit_state *ps = &pit->pit_state;
 246
 247         if (atomic_read(&ps->reinject) && !atomic_xchg(&ps->irq_ack, 0))
 248                 return;
 249
 250         kvm_set_irq(kvm, pit->irq_source_id, 0, 1, false);
 251         kvm_set_irq(kvm, pit->irq_source_id, 0, 0, false);
 252
 253         /*
 254          * Provides NMI watchdog support via Virtual Wire mode.
 255          * The route is: PIT -> LVT0 in NMI mode.
 256          *
 257          * Note: Our Virtual Wire implementation does not follow
 258          * the MP specification.  We propagate a PIT interrupt to all
 259          * VCPUs and only when LVT0 is in NMI mode.  The interrupt can
 260          * also be simultaneously delivered through PIC and IOAPIC.
 261          */
 262         if (atomic_read(&kvm->arch.vapics_in_nmi_mode) > 0)
 263                 kvm_for_each_vcpu(i, vcpu, kvm)
 264                         kvm_apic_nmi_wd_deliver(vcpu);
 265 }
 266
 267 static enum hrtimer_restart pit_timer_fn(struct hrtimer *data)
 268 {
 269         struct kvm_kpit_state *ps = container_of(data, struct kvm_kpit_state, timer);
 270         struct kvm_pit *pt = pit_state_to_pit(ps);
 271
 272         if (atomic_read(&ps->reinject))
 273                 atomic_inc(&ps->pending);
 274
 275         queue_kthread_work(&pt->worker, &pt->expired);
 276
 277         if (ps->is_periodic) {
 278                 hrtimer_add_expires_ns(&ps->timer, ps->period);
 279                 return HRTIMER_RESTART;
 280         } else
 281                 return HRTIMER_NORESTART;
 282 }
 283
 284 static inline void kvm_pit_reset_reinject(struct kvm_pit *pit)
 285 {
 286         atomic_set(&pit->pit_state.pending, 0);
 287         atomic_set(&pit->pit_state.irq_ack, 1);
 288 }
 289
 290 void kvm_pit_set_reinject(struct kvm_pit *pit, bool reinject)
 291 {
 292         struct kvm_kpit_state *ps = &pit->pit_state;
 293         struct kvm *kvm = pit->kvm;
 294
 295         if (atomic_read(&ps->reinject) == reinject)
 296                 return;
 297
 298         if (reinject) {
 299                 /* The initial state is preserved while ps->reinject == 0. */
 300                 kvm_pit_reset_reinject(pit);
 301                 kvm_register_irq_ack_notifier(kvm, &ps->irq_ack_notifier);
 302                 kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
 303         } else {
 304                 kvm_unregister_irq_ack_notifier(kvm, &ps->irq_ack_notifier);
 305                 kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
 306         }
 307
 308         atomic_set(&ps->reinject, reinject);
 309 }
 310
 311 static void create_pit_timer(struct kvm_pit *pit, u32 val, int is_period)
 312 {
 313         struct kvm_kpit_state *ps = &pit->pit_state;
 314         struct kvm *kvm = pit->kvm;
 315         s64 interval;
 316
 317         if (!ioapic_in_kernel(kvm) ||
 318             ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)
 319                 return;
 320
 321         interval = mul_u64_u32_div(val, NSEC_PER_SEC, KVM_PIT_FREQ);
 322
 323         pr_debug("create pit timer, interval is %llu nsec\n", interval);
 324
 325         /* TODO The new value only affected after the retriggered */
 326         hrtimer_cancel(&ps->timer);
 327         flush_kthread_work(&pit->expired);
 328         ps->period = interval;
 329         ps->is_periodic = is_period;
 330
 331         kvm_pit_reset_reinject(pit);
 332
 333         /*
 334          * Do not allow the guest to program periodic timers with small
 335          * interval, since the hrtimers are not throttled by the host
 336          * scheduler.
 337          */
 338         if (ps->is_periodic) {
 339                 s64 min_period = min_timer_period_us * 1000LL;
 340
 341                 if (ps->period < min_period) {
 342                         pr_info_ratelimited(
 343                             "kvm: requested %lld ns "
 344                             "i8254 timer period limited to %lld ns\n",
 345                             ps->period, min_period);
 346                         ps->period = min_period;
 347                 }
 348         }
 349
 350         hrtimer_start(&ps->timer, ktime_add_ns(ktime_get(), interval),
 351                       HRTIMER_MODE_ABS);
 352 }
 353
 354 static void pit_load_count(struct kvm_pit *pit, int channel, u32 val)
 355 {
 356         struct kvm_kpit_state *ps = &pit->pit_state;
 357
 358         pr_debug("load_count val is %d, channel is %d\n", val, channel);
 359
 360         /*
 361          * The largest possible initial count is 0; this is equivalent
 362          * to 216 for binary counting and 104 for BCD counting.
 363          */
 364         if (val == 0)
 365                 val = 0x10000;
 366
 367         ps->channels[channel].count = val;
 368
 369         if (channel != 0) {
 370                 ps->channels[channel].count_load_time = ktime_get();
 371                 return;
 372         }
 373
 374         /* Two types of timer
 375          * mode 1 is one shot, mode 2 is period, otherwise del timer */
 376         switch (ps->channels[0].mode) {
 377         case 0:
 378         case 1:
 379         /* FIXME: enhance mode 4 precision */
 380         case 4:
 381                 create_pit_timer(pit, val, 0);
 382                 break;
 383         case 2:
 384         case 3:
 385                 create_pit_timer(pit, val, 1);
 386                 break;
 387         default:
 388                 destroy_pit_timer(pit);
 389         }
 390 }
 391
 392 void kvm_pit_load_count(struct kvm_pit *pit, int channel, u32 val,
 393                 int hpet_legacy_start)
 394 {
 395         u8 saved_mode;
 396
 397         WARN_ON_ONCE(!mutex_is_locked(&pit->pit_state.lock));
 398
 399         if (hpet_legacy_start) {
 400                 /* save existing mode for later reenablement */
 401                 WARN_ON(channel != 0);
 402                 saved_mode = pit->pit_state.channels[0].mode;
 403                 pit->pit_state.channels[0].mode = 0xff; /* disable timer */
 404                 pit_load_count(pit, channel, val);
 405                 pit->pit_state.channels[0].mode = saved_mode;
 406         } else {
 407                 pit_load_count(pit, channel, val);
 408         }
 409 }
 410
 411 static inline struct kvm_pit *dev_to_pit(struct kvm_io_device *dev)
 412 {
 413         return container_of(dev, struct kvm_pit, dev);
 414 }
 415
 416 static inline struct kvm_pit *speaker_to_pit(struct kvm_io_device *dev)
 417 {
 418         return container_of(dev, struct kvm_pit, speaker_dev);
 419 }
 420
 421 static inline int pit_in_range(gpa_t addr)
 422 {
 423         return ((addr >= KVM_PIT_BASE_ADDRESS) &&
 424                 (addr < KVM_PIT_BASE_ADDRESS + KVM_PIT_MEM_LENGTH));
 425 }
 426
 427 static int pit_ioport_write(struct kvm_vcpu *vcpu,
 428                                 struct kvm_io_device *this,
 429                             gpa_t addr, int len, const void *data)
 430 {
 431         struct kvm_pit *pit = dev_to_pit(this);
 432         struct kvm_kpit_state *pit_state = &pit->pit_state;
 433         int channel, access;
 434         struct kvm_kpit_channel_state *s;
 435         u32 val = *(u32 *) data;
 436         if (!pit_in_range(addr))
 437                 return -EOPNOTSUPP;
 438
 439         val  &= 0xff;
 440         addr &= KVM_PIT_CHANNEL_MASK;
 441
 442         mutex_lock(&pit_state->lock);
 443
 444         if (val != 0)
 445                 pr_debug("write addr is 0x%x, len is %d, val is 0x%x\n",
 446                          (unsigned int)addr, len, val);
 447
 448         if (addr == 3) {
 449                 channel = val >> 6;
 450                 if (channel == 3) {
 451                         /* Read-Back Command. */
 452                         for (channel = 0; channel < 3; channel++) {
 453                                 s = &pit_state->channels[channel];
 454                                 if (val & (2 << channel)) {
 455                                         if (!(val & 0x20))
 456                                                 pit_latch_count(pit, channel);
 457                                         if (!(val & 0x10))
 458                                                 pit_latch_status(pit, channel);
 459                                 }
 460                         }
 461                 } else {
 462                         /* Select Counter <channel>. */
 463                         s = &pit_state->channels[channel];
 464                         access = (val >> 4) & KVM_PIT_CHANNEL_MASK;
 465                         if (access == 0) {
 466                                 pit_latch_count(pit, channel);
 467                         } else {
 468                                 s->rw_mode = access;
 469                                 s->read_state = access;
 470                                 s->write_state = access;
 471                                 s->mode = (val >> 1) & 7;
 472                                 if (s->mode > 5)
 473                                         s->mode -= 4;
 474                                 s->bcd = val & 1;
 475                         }
 476                 }
 477         } else {
 478                 /* Write Count. */
 479                 s = &pit_state->channels[addr];
 480                 switch (s->write_state) {
 481                 default:
 482                 case RW_STATE_LSB:
 483                         pit_load_count(pit, addr, val);
 484                         break;
 485                 case RW_STATE_MSB:
 486                         pit_load_count(pit, addr, val << 8);
 487                         break;
 488                 case RW_STATE_WORD0:
 489                         s->write_latch = val;
 490                         s->write_state = RW_STATE_WORD1;
 491                         break;
 492                 case RW_STATE_WORD1:
 493                         pit_load_count(pit, addr, s->write_latch | (val << 8));
 494                         s->write_state = RW_STATE_WORD0;
 495                         break;
 496                 }
 497         }
 498
 499         mutex_unlock(&pit_state->lock);
 500         return 0;
 501 }
 502
 503 static int pit_ioport_read(struct kvm_vcpu *vcpu,
 504                            struct kvm_io_device *this,
 505                            gpa_t addr, int len, void *data)
 506 {
 507         struct kvm_pit *pit = dev_to_pit(this);
 508         struct kvm_kpit_state *pit_state = &pit->pit_state;
 509         int ret, count;
 510         struct kvm_kpit_channel_state *s;
 511         if (!pit_in_range(addr))
 512                 return -EOPNOTSUPP;
 513
 514         addr &= KVM_PIT_CHANNEL_MASK;
 515         if (addr == 3)
 516                 return 0;
 517
 518         s = &pit_state->channels[addr];
 519
 520         mutex_lock(&pit_state->lock);
 521
 522         if (s->status_latched) {
 523                 s->status_latched = 0;
 524                 ret = s->status;
 525         } else if (s->count_latched) {
 526                 switch (s->count_latched) {
 527                 default:
 528                 case RW_STATE_LSB:
 529                         ret = s->latched_count & 0xff;
 530                         s->count_latched = 0;
 531                         break;
 532                 case RW_STATE_MSB:
 533                         ret = s->latched_count >> 8;
 534                         s->count_latched = 0;
 535                         break;
 536                 case RW_STATE_WORD0:
 537                         ret = s->latched_count & 0xff;
 538                         s->count_latched = RW_STATE_MSB;
 539                         break;
 540                 }
 541         } else {
 542                 switch (s->read_state) {
 543                 default:
 544                 case RW_STATE_LSB:
 545                         count = pit_get_count(pit, addr);
 546                         ret = count & 0xff;
 547                         break;
 548                 case RW_STATE_MSB:
 549                         count = pit_get_count(pit, addr);
 550                         ret = (count >> 8) & 0xff;
 551                         break;
 552                 case RW_STATE_WORD0:
 553                         count = pit_get_count(pit, addr);
 554                         ret = count & 0xff;
 555                         s->read_state = RW_STATE_WORD1;
 556                         break;
 557                 case RW_STATE_WORD1:
 558                         count = pit_get_count(pit, addr);
 559                         ret = (count >> 8) & 0xff;
 560                         s->read_state = RW_STATE_WORD0;
 561                         break;
 562                 }
 563         }
 564
 565         if (len > sizeof(ret))
 566                 len = sizeof(ret);
 567         memcpy(data, (char *)&ret, len);
 568
 569         mutex_unlock(&pit_state->lock);
 570         return 0;
 571 }
 572
 573 static int speaker_ioport_write(struct kvm_vcpu *vcpu,
 574                                 struct kvm_io_device *this,
 575                                 gpa_t addr, int len, const void *data)
 576 {
 577         struct kvm_pit *pit = speaker_to_pit(this);
 578         struct kvm_kpit_state *pit_state = &pit->pit_state;
 579         u32 val = *(u32 *) data;
 580         if (addr != KVM_SPEAKER_BASE_ADDRESS)
 581                 return -EOPNOTSUPP;
 582
 583         mutex_lock(&pit_state->lock);
 584         pit_state->speaker_data_on = (val >> 1) & 1;
 585         pit_set_gate(pit, 2, val & 1);
 586         mutex_unlock(&pit_state->lock);
 587         return 0;
 588 }
 589
 590 static int speaker_ioport_read(struct kvm_vcpu *vcpu,
 591                                    struct kvm_io_device *this,
 592                                    gpa_t addr, int len, void *data)
 593 {
 594         struct kvm_pit *pit = speaker_to_pit(this);
 595         struct kvm_kpit_state *pit_state = &pit->pit_state;
 596         unsigned int refresh_clock;
 597         int ret;
 598         if (addr != KVM_SPEAKER_BASE_ADDRESS)
 599                 return -EOPNOTSUPP;
 600
 601         /* Refresh clock toggles at about 15us. We approximate as 2^14ns. */
 602         refresh_clock = ((unsigned int)ktime_to_ns(ktime_get()) >> 14) & 1;
 603
 604         mutex_lock(&pit_state->lock);
 605         ret = ((pit_state->speaker_data_on << 1) | pit_get_gate(pit, 2) |
 606                 (pit_get_out(pit, 2) << 5) | (refresh_clock << 4));
 607         if (len > sizeof(ret))
 608                 len = sizeof(ret);
 609         memcpy(data, (char *)&ret, len);
 610         mutex_unlock(&pit_state->lock);
 611         return 0;
 612 }
 613
 614 static void kvm_pit_reset(struct kvm_pit *pit)
 615 {
 616         int i;
 617         struct kvm_kpit_channel_state *c;
 618
 619         pit->pit_state.flags = 0;
 620         for (i = 0; i < 3; i++) {
 621                 c = &pit->pit_state.channels[i];
 622                 c->mode = 0xff;
 623                 c->gate = (i != 2);
 624                 pit_load_count(pit, i, 0);
 625         }
 626
 627         kvm_pit_reset_reinject(pit);
 628 }
 629
 630 static void pit_mask_notifer(struct kvm_irq_mask_notifier *kimn, bool mask)
 631 {
 632         struct kvm_pit *pit = container_of(kimn, struct kvm_pit, mask_notifier);
 633
 634         if (!mask)
 635                 kvm_pit_reset_reinject(pit);
 636 }
 637
 638 static const struct kvm_io_device_ops pit_dev_ops = {
 639         .read     = pit_ioport_read,
 640         .write    = pit_ioport_write,
 641 };
 642
 643 static const struct kvm_io_device_ops speaker_dev_ops = {
 644         .read     = speaker_ioport_read,
 645         .write    = speaker_ioport_write,
 646 };
 647
 648 /* Caller must hold slots_lock */
 649 struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
 650 {
 651         struct kvm_pit *pit;
 652         struct kvm_kpit_state *pit_state;
 653         struct pid *pid;
 654         pid_t pid_nr;
 655         int ret;
 656
 657         pit = kzalloc(sizeof(struct kvm_pit), GFP_KERNEL);
 658         if (!pit)
 659                 return NULL;
 660
 661         pit->irq_source_id = kvm_request_irq_source_id(kvm);
 662         if (pit->irq_source_id < 0)
 663                 goto fail_request;
 664
 665         mutex_init(&pit->pit_state.lock);
 666
 667         pid = get_pid(task_tgid(current));
 668         pid_nr = pid_vnr(pid);
 669         put_pid(pid);
 670
 671         init_kthread_worker(&pit->worker);
 672         pit->worker_task = kthread_run(kthread_worker_fn, &pit->worker,
 673                                        "kvm-pit/%d", pid_nr);
 674         if (IS_ERR(pit->worker_task))
 675                 goto fail_kthread;
 676
 677         init_kthread_work(&pit->expired, pit_do_work);
 678
 679         pit->kvm = kvm;
 680
 681         pit_state = &pit->pit_state;
 682         hrtimer_init(&pit_state->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 683         pit_state->timer.function = pit_timer_fn;
 684
 685         pit_state->irq_ack_notifier.gsi = 0;
 686         pit_state->irq_ack_notifier.irq_acked = kvm_pit_ack_irq;
 687         pit->mask_notifier.func = pit_mask_notifer;
 688
 689         kvm_pit_reset(pit);
 690
 691         kvm_pit_set_reinject(pit, true);
 692
 693         kvm_iodevice_init(&pit->dev, &pit_dev_ops);
 694         ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, KVM_PIT_BASE_ADDRESS,
 695                                       KVM_PIT_MEM_LENGTH, &pit->dev);
 696         if (ret < 0)
 697                 goto fail_register_pit;
 698
 699         if (flags & KVM_PIT_SPEAKER_DUMMY) {
 700                 kvm_iodevice_init(&pit->speaker_dev, &speaker_dev_ops);
 701                 ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS,
 702                                               KVM_SPEAKER_BASE_ADDRESS, 4,
 703                                               &pit->speaker_dev);
 704                 if (ret < 0)
 705                         goto fail_register_speaker;
 706         }
 707
 708         return pit;
 709
 710 fail_register_speaker:
 711         kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev);
 712 fail_register_pit:
 713         kvm_pit_set_reinject(pit, false);
 714         kthread_stop(pit->worker_task);
 715 fail_kthread:
 716         kvm_free_irq_source_id(kvm, pit->irq_source_id);
 717 fail_request:
 718         kfree(pit);
 719         return NULL;
 720 }
 721
 722 void kvm_free_pit(struct kvm *kvm)
 723 {
 724         struct kvm_pit *pit = kvm->arch.vpit;
 725
 726         if (pit) {
 727                 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev);
 728                 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->speaker_dev);
 729                 kvm_pit_set_reinject(pit, false);
 730                 hrtimer_cancel(&pit->pit_state.timer);
 731                 flush_kthread_work(&pit->expired);
 732                 kthread_stop(pit->worker_task);
 733                 kvm_free_irq_source_id(kvm, pit->irq_source_id);
 734                 kfree(pit);
 735         }
 736 }