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 "irq.h"
  39 #include "i8254.h"
  40 #include "x86.h"
  41
  42 #ifndef CONFIG_X86_64
  43 #define mod_64(x, y) ((x) - (y) * div64_u64(x, y))
  44 #else
  45 #define mod_64(x, y) ((x) % (y))
  46 #endif
  47
  48 #define RW_STATE_LSB 1
  49 #define RW_STATE_MSB 2
  50 #define RW_STATE_WORD0 3
  51 #define RW_STATE_WORD1 4
  52
  53 /* Compute with 96 bit intermediate result: (a*b)/c */
  54 static u64 muldiv64(u64 a, u32 b, u32 c)
  55 {
  56         union {
  57                 u64 ll;
  58                 struct {
  59                         u32 low, high;
  60                 } l;
  61         } u, res;
  62         u64 rl, rh;
  63
  64         u.ll = a;
  65         rl = (u64)u.l.low * (u64)b;
  66         rh = (u64)u.l.high * (u64)b;
  67         rh += (rl >> 32);
  68         res.l.high = div64_u64(rh, c);
  69         res.l.low = div64_u64(((mod_64(rh, c) << 32) + (rl & 0xffffffff)), c);
  70         return res.ll;
  71 }
  72
  73 static void pit_set_gate(struct kvm *kvm, int channel, u32 val)
  74 {
  75         struct kvm_kpit_channel_state *c =
  76                 &kvm->arch.vpit->pit_state.channels[channel];
  77
  78         WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
  79
  80         switch (c->mode) {
  81         default:
  82         case 0:
  83         case 4:
  84                 /* XXX: just disable/enable counting */
  85                 break;
  86         case 1:
  87         case 2:
  88         case 3:
  89         case 5:
  90                 /* Restart counting on rising edge. */
  91                 if (c->gate < val)
  92                         c->count_load_time = ktime_get();
  93                 break;
  94         }
  95
  96         c->gate = val;
  97 }
  98
  99 static int pit_get_gate(struct kvm *kvm, int channel)
 100 {
 101         WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 102
 103         return kvm->arch.vpit->pit_state.channels[channel].gate;
 104 }
 105
 106 static s64 __kpit_elapsed(struct kvm *kvm)
 107 {
 108         s64 elapsed;
 109         ktime_t remaining;
 110         struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
 111
 112         if (!ps->period)
 113                 return 0;
 114
 115         /*
 116          * The Counter does not stop when it reaches zero. In
 117          * Modes 0, 1, 4, and 5 the Counter ``wraps around'' to
 118          * the highest count, either FFFF hex for binary counting
 119          * or 9999 for BCD counting, and continues counting.
 120          * Modes 2 and 3 are periodic; the Counter reloads
 121          * itself with the initial count and continues counting
 122          * from there.
 123          */
 124         remaining = hrtimer_get_remaining(&ps->timer);
 125         elapsed = ps->period - ktime_to_ns(remaining);
 126
 127         return elapsed;
 128 }
 129
 130 static s64 kpit_elapsed(struct kvm *kvm, struct kvm_kpit_channel_state *c,
 131                         int channel)
 132 {
 133         if (channel == 0)
 134                 return __kpit_elapsed(kvm);
 135
 136         return ktime_to_ns(ktime_sub(ktime_get(), c->count_load_time));
 137 }
 138
 139 static int pit_get_count(struct kvm *kvm, int channel)
 140 {
 141         struct kvm_kpit_channel_state *c =
 142                 &kvm->arch.vpit->pit_state.channels[channel];
 143         s64 d, t;
 144         int counter;
 145
 146         WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 147
 148         t = kpit_elapsed(kvm, c, channel);
 149         d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC);
 150
 151         switch (c->mode) {
 152         case 0:
 153         case 1:
 154         case 4:
 155         case 5:
 156                 counter = (c->count - d) & 0xffff;
 157                 break;
 158         case 3:
 159                 /* XXX: may be incorrect for odd counts */
 160                 counter = c->count - (mod_64((2 * d), c->count));
 161                 break;
 162         default:
 163                 counter = c->count - mod_64(d, c->count);
 164                 break;
 165         }
 166         return counter;
 167 }
 168
 169 static int pit_get_out(struct kvm *kvm, int channel)
 170 {
 171         struct kvm_kpit_channel_state *c =
 172                 &kvm->arch.vpit->pit_state.channels[channel];
 173         s64 d, t;
 174         int out;
 175
 176         WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 177
 178         t = kpit_elapsed(kvm, c, channel);
 179         d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC);
 180
 181         switch (c->mode) {
 182         default:
 183         case 0:
 184                 out = (d >= c->count);
 185                 break;
 186         case 1:
 187                 out = (d < c->count);
 188                 break;
 189         case 2:
 190                 out = ((mod_64(d, c->count) == 0) && (d != 0));
 191                 break;
 192         case 3:
 193                 out = (mod_64(d, c->count) < ((c->count + 1) >> 1));
 194                 break;
 195         case 4:
 196         case 5:
 197                 out = (d == c->count);
 198                 break;
 199         }
 200
 201         return out;
 202 }
 203
 204 static void pit_latch_count(struct kvm *kvm, int channel)
 205 {
 206         struct kvm_kpit_channel_state *c =
 207                 &kvm->arch.vpit->pit_state.channels[channel];
 208
 209         WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 210
 211         if (!c->count_latched) {
 212                 c->latched_count = pit_get_count(kvm, channel);
 213                 c->count_latched = c->rw_mode;
 214         }
 215 }
 216
 217 static void pit_latch_status(struct kvm *kvm, int channel)
 218 {
 219         struct kvm_kpit_channel_state *c =
 220                 &kvm->arch.vpit->pit_state.channels[channel];
 221
 222         WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 223
 224         if (!c->status_latched) {
 225                 /* TODO: Return NULL COUNT (bit 6). */
 226                 c->status = ((pit_get_out(kvm, channel) << 7) |
 227                                 (c->rw_mode << 4) |
 228                                 (c->mode << 1) |
 229                                 c->bcd);
 230                 c->status_latched = 1;
 231         }
 232 }
 233
 234 static void kvm_pit_ack_irq(struct kvm_irq_ack_notifier *kian)
 235 {
 236         struct kvm_kpit_state *ps = container_of(kian, struct kvm_kpit_state,
 237                                                  irq_ack_notifier);
 238         int value;
 239
 240         spin_lock(&ps->inject_lock);
 241         value = atomic_dec_return(&ps->pending);
 242         if (value < 0)
 243                 /* spurious acks can be generated if, for example, the
 244                  * PIC is being reset.  Handle it gracefully here
 245                  */
 246                 atomic_inc(&ps->pending);
 247         else if (value > 0)
 248                 /* in this case, we had multiple outstanding pit interrupts
 249                  * that we needed to inject.  Reinject
 250                  */
 251                 queue_kthread_work(&ps->pit->worker, &ps->pit->expired);
 252         ps->irq_ack = 1;
 253         spin_unlock(&ps->inject_lock);
 254 }
 255
 256 void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu)
 257 {
 258         struct kvm_pit *pit = vcpu->kvm->arch.vpit;
 259         struct hrtimer *timer;
 260
 261         if (!kvm_vcpu_is_bsp(vcpu) || !pit)
 262                 return;
 263
 264         timer = &pit->pit_state.timer;
 265         if (hrtimer_cancel(timer))
 266                 hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 267 }
 268
 269 static void destroy_pit_timer(struct kvm_pit *pit)
 270 {
 271         hrtimer_cancel(&pit->pit_state.timer);
 272         flush_kthread_work(&pit->expired);
 273 }
 274
 275 static void pit_do_work(struct kthread_work *work)
 276 {
 277         struct kvm_pit *pit = container_of(work, struct kvm_pit, expired);
 278         struct kvm *kvm = pit->kvm;
 279         struct kvm_vcpu *vcpu;
 280         int i;
 281         struct kvm_kpit_state *ps = &pit->pit_state;
 282         int inject = 0;
 283
 284         /* Try to inject pending interrupts when
 285          * last one has been acked.
 286          */
 287         spin_lock(&ps->inject_lock);
 288         if (ps->irq_ack) {
 289                 ps->irq_ack = 0;
 290                 inject = 1;
 291         }
 292         spin_unlock(&ps->inject_lock);
 293         if (inject) {
 294                 kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 1, false);
 295                 kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 0, false);
 296
 297                 /*
 298                  * Provides NMI watchdog support via Virtual Wire mode.
 299                  * The route is: PIT -> PIC -> LVT0 in NMI mode.
 300                  *
 301                  * Note: Our Virtual Wire implementation is simplified, only
 302                  * propagating PIT interrupts to all VCPUs when they have set
 303                  * LVT0 to NMI delivery. Other PIC interrupts are just sent to
 304                  * VCPU0, and only if its LVT0 is in EXTINT mode.
 305                  */
 306                 if (kvm->arch.vapics_in_nmi_mode > 0)
 307                         kvm_for_each_vcpu(i, vcpu, kvm)
 308                                 kvm_apic_nmi_wd_deliver(vcpu);
 309         }
 310 }
 311
 312 static enum hrtimer_restart pit_timer_fn(struct hrtimer *data)
 313 {
 314         struct kvm_kpit_state *ps = container_of(data, struct kvm_kpit_state, timer);
 315         struct kvm_pit *pt = ps->kvm->arch.vpit;
 316
 317         if (ps->reinject || !atomic_read(&ps->pending)) {
 318                 atomic_inc(&ps->pending);
 319                 queue_kthread_work(&pt->worker, &pt->expired);
 320         }
 321
 322         if (ps->is_periodic) {
 323                 hrtimer_add_expires_ns(&ps->timer, ps->period);
 324                 return HRTIMER_RESTART;
 325         } else
 326                 return HRTIMER_NORESTART;
 327 }
 328
 329 static void create_pit_timer(struct kvm *kvm, u32 val, int is_period)
 330 {
 331         struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
 332         s64 interval;
 333
 334         if (!irqchip_in_kernel(kvm) || ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)
 335                 return;
 336
 337         interval = muldiv64(val, NSEC_PER_SEC, KVM_PIT_FREQ);
 338
 339         pr_debug("create pit timer, interval is %llu nsec\n", interval);
 340
 341         /* TODO The new value only affected after the retriggered */
 342         hrtimer_cancel(&ps->timer);
 343         flush_kthread_work(&ps->pit->expired);
 344         ps->period = interval;
 345         ps->is_periodic = is_period;
 346
 347         ps->timer.function = pit_timer_fn;
 348         ps->kvm = ps->pit->kvm;
 349
 350         atomic_set(&ps->pending, 0);
 351         ps->irq_ack = 1;
 352
 353         /*
 354          * Do not allow the guest to program periodic timers with small
 355          * interval, since the hrtimers are not throttled by the host
 356          * scheduler.
 357          */
 358         if (ps->is_periodic) {
 359                 s64 min_period = min_timer_period_us * 1000LL;
 360
 361                 if (ps->period < min_period) {
 362                         pr_info_ratelimited(
 363                             "kvm: requested %lld ns "
 364                             "i8254 timer period limited to %lld ns\n",
 365                             ps->period, min_period);
 366                         ps->period = min_period;
 367                 }
 368         }
 369
 370         hrtimer_start(&ps->timer, ktime_add_ns(ktime_get(), interval),
 371                       HRTIMER_MODE_ABS);
 372 }
 373
 374 static void pit_load_count(struct kvm *kvm, int channel, u32 val)
 375 {
 376         struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
 377
 378         WARN_ON(!mutex_is_locked(&ps->lock));
 379
 380         pr_debug("load_count val is %d, channel is %d\n", val, channel);
 381
 382         /*
 383          * The largest possible initial count is 0; this is equivalent
 384          * to 216 for binary counting and 104 for BCD counting.
 385          */
 386         if (val == 0)
 387                 val = 0x10000;
 388
 389         ps->channels[channel].count = val;
 390
 391         if (channel != 0) {
 392                 ps->channels[channel].count_load_time = ktime_get();
 393                 return;
 394         }
 395
 396         /* Two types of timer
 397          * mode 1 is one shot, mode 2 is period, otherwise del timer */
 398         switch (ps->channels[0].mode) {
 399         case 0:
 400         case 1:
 401         /* FIXME: enhance mode 4 precision */
 402         case 4:
 403                 create_pit_timer(kvm, val, 0);
 404                 break;
 405         case 2:
 406         case 3:
 407                 create_pit_timer(kvm, val, 1);
 408                 break;
 409         default:
 410                 destroy_pit_timer(kvm->arch.vpit);
 411         }
 412 }
 413
 414 void kvm_pit_load_count(struct kvm *kvm, int channel, u32 val, int hpet_legacy_start)
 415 {
 416         u8 saved_mode;
 417         if (hpet_legacy_start) {
 418                 /* save existing mode for later reenablement */
 419                 saved_mode = kvm->arch.vpit->pit_state.channels[0].mode;
 420                 kvm->arch.vpit->pit_state.channels[0].mode = 0xff; /* disable timer */
 421                 pit_load_count(kvm, channel, val);
 422                 kvm->arch.vpit->pit_state.channels[0].mode = saved_mode;
 423         } else {
 424                 pit_load_count(kvm, channel, val);
 425         }
 426 }
 427
 428 static inline struct kvm_pit *dev_to_pit(struct kvm_io_device *dev)
 429 {
 430         return container_of(dev, struct kvm_pit, dev);
 431 }
 432
 433 static inline struct kvm_pit *speaker_to_pit(struct kvm_io_device *dev)
 434 {
 435         return container_of(dev, struct kvm_pit, speaker_dev);
 436 }
 437
 438 static inline int pit_in_range(gpa_t addr)
 439 {
 440         return ((addr >= KVM_PIT_BASE_ADDRESS) &&
 441                 (addr < KVM_PIT_BASE_ADDRESS + KVM_PIT_MEM_LENGTH));
 442 }
 443
 444 static int pit_ioport_write(struct kvm_io_device *this,
 445                             gpa_t addr, int len, const void *data)
 446 {
 447         struct kvm_pit *pit = dev_to_pit(this);
 448         struct kvm_kpit_state *pit_state = &pit->pit_state;
 449         struct kvm *kvm = pit->kvm;
 450         int channel, access;
 451         struct kvm_kpit_channel_state *s;
 452         u32 val = *(u32 *) data;
 453         if (!pit_in_range(addr))
 454                 return -EOPNOTSUPP;
 455
 456         val  &= 0xff;
 457         addr &= KVM_PIT_CHANNEL_MASK;
 458
 459         mutex_lock(&pit_state->lock);
 460
 461         if (val != 0)
 462                 pr_debug("write addr is 0x%x, len is %d, val is 0x%x\n",
 463                          (unsigned int)addr, len, val);
 464
 465         if (addr == 3) {
 466                 channel = val >> 6;
 467                 if (channel == 3) {
 468                         /* Read-Back Command. */
 469                         for (channel = 0; channel < 3; channel++) {
 470                                 s = &pit_state->channels[channel];
 471                                 if (val & (2 << channel)) {
 472                                         if (!(val & 0x20))
 473                                                 pit_latch_count(kvm, channel);
 474                                         if (!(val & 0x10))
 475                                                 pit_latch_status(kvm, channel);
 476                                 }
 477                         }
 478                 } else {
 479                         /* Select Counter <channel>. */
 480                         s = &pit_state->channels[channel];
 481                         access = (val >> 4) & KVM_PIT_CHANNEL_MASK;
 482                         if (access == 0) {
 483                                 pit_latch_count(kvm, channel);
 484                         } else {
 485                                 s->rw_mode = access;
 486                                 s->read_state = access;
 487                                 s->write_state = access;
 488                                 s->mode = (val >> 1) & 7;
 489                                 if (s->mode > 5)
 490                                         s->mode -= 4;
 491                                 s->bcd = val & 1;
 492                         }
 493                 }
 494         } else {
 495                 /* Write Count. */
 496                 s = &pit_state->channels[addr];
 497                 switch (s->write_state) {
 498                 default:
 499                 case RW_STATE_LSB:
 500                         pit_load_count(kvm, addr, val);
 501                         break;
 502                 case RW_STATE_MSB:
 503                         pit_load_count(kvm, addr, val << 8);
 504                         break;
 505                 case RW_STATE_WORD0:
 506                         s->write_latch = val;
 507                         s->write_state = RW_STATE_WORD1;
 508                         break;
 509                 case RW_STATE_WORD1:
 510                         pit_load_count(kvm, addr, s->write_latch | (val << 8));
 511                         s->write_state = RW_STATE_WORD0;
 512                         break;
 513                 }
 514         }
 515
 516         mutex_unlock(&pit_state->lock);
 517         return 0;
 518 }
 519
 520 static int pit_ioport_read(struct kvm_io_device *this,
 521                            gpa_t addr, int len, void *data)
 522 {
 523         struct kvm_pit *pit = dev_to_pit(this);
 524         struct kvm_kpit_state *pit_state = &pit->pit_state;
 525         struct kvm *kvm = pit->kvm;
 526         int ret, count;
 527         struct kvm_kpit_channel_state *s;
 528         if (!pit_in_range(addr))
 529                 return -EOPNOTSUPP;
 530
 531         addr &= KVM_PIT_CHANNEL_MASK;
 532         if (addr == 3)
 533                 return 0;
 534
 535         s = &pit_state->channels[addr];
 536
 537         mutex_lock(&pit_state->lock);
 538
 539         if (s->status_latched) {
 540                 s->status_latched = 0;
 541                 ret = s->status;
 542         } else if (s->count_latched) {
 543                 switch (s->count_latched) {
 544                 default:
 545                 case RW_STATE_LSB:
 546                         ret = s->latched_count & 0xff;
 547                         s->count_latched = 0;
 548                         break;
 549                 case RW_STATE_MSB:
 550                         ret = s->latched_count >> 8;
 551                         s->count_latched = 0;
 552                         break;
 553                 case RW_STATE_WORD0:
 554                         ret = s->latched_count & 0xff;
 555                         s->count_latched = RW_STATE_MSB;
 556                         break;
 557                 }
 558         } else {
 559                 switch (s->read_state) {
 560                 default:
 561                 case RW_STATE_LSB:
 562                         count = pit_get_count(kvm, addr);
 563                         ret = count & 0xff;
 564                         break;
 565                 case RW_STATE_MSB:
 566                         count = pit_get_count(kvm, addr);
 567                         ret = (count >> 8) & 0xff;
 568                         break;
 569                 case RW_STATE_WORD0:
 570                         count = pit_get_count(kvm, addr);
 571                         ret = count & 0xff;
 572                         s->read_state = RW_STATE_WORD1;
 573                         break;
 574                 case RW_STATE_WORD1:
 575                         count = pit_get_count(kvm, addr);
 576                         ret = (count >> 8) & 0xff;
 577                         s->read_state = RW_STATE_WORD0;
 578                         break;
 579                 }
 580         }
 581
 582         if (len > sizeof(ret))
 583                 len = sizeof(ret);
 584         memcpy(data, (char *)&ret, len);
 585
 586         mutex_unlock(&pit_state->lock);
 587         return 0;
 588 }
 589
 590 static int speaker_ioport_write(struct kvm_io_device *this,
 591                                 gpa_t addr, int len, const void *data)
 592 {
 593         struct kvm_pit *pit = speaker_to_pit(this);
 594         struct kvm_kpit_state *pit_state = &pit->pit_state;
 595         struct kvm *kvm = pit->kvm;
 596         u32 val = *(u32 *) data;
 597         if (addr != KVM_SPEAKER_BASE_ADDRESS)
 598                 return -EOPNOTSUPP;
 599
 600         mutex_lock(&pit_state->lock);
 601         pit_state->speaker_data_on = (val >> 1) & 1;
 602         pit_set_gate(kvm, 2, val & 1);
 603         mutex_unlock(&pit_state->lock);
 604         return 0;
 605 }
 606
 607 static int speaker_ioport_read(struct kvm_io_device *this,
 608                                gpa_t addr, int len, void *data)
 609 {
 610         struct kvm_pit *pit = speaker_to_pit(this);
 611         struct kvm_kpit_state *pit_state = &pit->pit_state;
 612         struct kvm *kvm = pit->kvm;
 613         unsigned int refresh_clock;
 614         int ret;
 615         if (addr != KVM_SPEAKER_BASE_ADDRESS)
 616                 return -EOPNOTSUPP;
 617
 618         /* Refresh clock toggles at about 15us. We approximate as 2^14ns. */
 619         refresh_clock = ((unsigned int)ktime_to_ns(ktime_get()) >> 14) & 1;
 620
 621         mutex_lock(&pit_state->lock);
 622         ret = ((pit_state->speaker_data_on << 1) | pit_get_gate(kvm, 2) |
 623                 (pit_get_out(kvm, 2) << 5) | (refresh_clock << 4));
 624         if (len > sizeof(ret))
 625                 len = sizeof(ret);
 626         memcpy(data, (char *)&ret, len);
 627         mutex_unlock(&pit_state->lock);
 628         return 0;
 629 }
 630
 631 void kvm_pit_reset(struct kvm_pit *pit)
 632 {
 633         int i;
 634         struct kvm_kpit_channel_state *c;
 635
 636         mutex_lock(&pit->pit_state.lock);
 637         pit->pit_state.flags = 0;
 638         for (i = 0; i < 3; i++) {
 639                 c = &pit->pit_state.channels[i];
 640                 c->mode = 0xff;
 641                 c->gate = (i != 2);
 642                 pit_load_count(pit->kvm, i, 0);
 643         }
 644         mutex_unlock(&pit->pit_state.lock);
 645
 646         atomic_set(&pit->pit_state.pending, 0);
 647         pit->pit_state.irq_ack = 1;
 648 }
 649
 650 static void pit_mask_notifer(struct kvm_irq_mask_notifier *kimn, bool mask)
 651 {
 652         struct kvm_pit *pit = container_of(kimn, struct kvm_pit, mask_notifier);
 653
 654         if (!mask) {
 655                 atomic_set(&pit->pit_state.pending, 0);
 656                 pit->pit_state.irq_ack = 1;
 657         }
 658 }
 659
 660 static const struct kvm_io_device_ops pit_dev_ops = {
 661         .read     = pit_ioport_read,
 662         .write    = pit_ioport_write,
 663 };
 664
 665 static const struct kvm_io_device_ops speaker_dev_ops = {
 666         .read     = speaker_ioport_read,
 667         .write    = speaker_ioport_write,
 668 };
 669
 670 /* Caller must hold slots_lock */
 671 struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
 672 {
 673         struct kvm_pit *pit;
 674         struct kvm_kpit_state *pit_state;
 675         struct pid *pid;
 676         pid_t pid_nr;
 677         int ret;
 678
 679         pit = kzalloc(sizeof(struct kvm_pit), GFP_KERNEL);
 680         if (!pit)
 681                 return NULL;
 682
 683         pit->irq_source_id = kvm_request_irq_source_id(kvm);
 684         if (pit->irq_source_id < 0) {
 685                 kfree(pit);
 686                 return NULL;
 687         }
 688
 689         mutex_init(&pit->pit_state.lock);
 690         mutex_lock(&pit->pit_state.lock);
 691         spin_lock_init(&pit->pit_state.inject_lock);
 692
 693         pid = get_pid(task_tgid(current));
 694         pid_nr = pid_vnr(pid);
 695         put_pid(pid);
 696
 697         init_kthread_worker(&pit->worker);
 698         pit->worker_task = kthread_run(kthread_worker_fn, &pit->worker,
 699                                        "kvm-pit/%d", pid_nr);
 700         if (IS_ERR(pit->worker_task)) {
 701                 mutex_unlock(&pit->pit_state.lock);
 702                 kvm_free_irq_source_id(kvm, pit->irq_source_id);
 703                 kfree(pit);
 704                 return NULL;
 705         }
 706         init_kthread_work(&pit->expired, pit_do_work);
 707
 708         kvm->arch.vpit = pit;
 709         pit->kvm = kvm;
 710
 711         pit_state = &pit->pit_state;
 712         pit_state->pit = pit;
 713         hrtimer_init(&pit_state->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 714         pit_state->irq_ack_notifier.gsi = 0;
 715         pit_state->irq_ack_notifier.irq_acked = kvm_pit_ack_irq;
 716         kvm_register_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
 717         pit_state->reinject = true;
 718         mutex_unlock(&pit->pit_state.lock);
 719
 720         kvm_pit_reset(pit);
 721
 722         pit->mask_notifier.func = pit_mask_notifer;
 723         kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
 724
 725         kvm_iodevice_init(&pit->dev, &pit_dev_ops);
 726         ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, KVM_PIT_BASE_ADDRESS,
 727                                       KVM_PIT_MEM_LENGTH, &pit->dev);
 728         if (ret < 0)
 729                 goto fail;
 730
 731         if (flags & KVM_PIT_SPEAKER_DUMMY) {
 732                 kvm_iodevice_init(&pit->speaker_dev, &speaker_dev_ops);
 733                 ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS,
 734                                               KVM_SPEAKER_BASE_ADDRESS, 4,
 735                                               &pit->speaker_dev);
 736                 if (ret < 0)
 737                         goto fail_unregister;
 738         }
 739
 740         return pit;
 741
 742 fail_unregister:
 743         kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev);
 744
 745 fail:
 746         kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
 747         kvm_unregister_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
 748         kvm_free_irq_source_id(kvm, pit->irq_source_id);
 749         kthread_stop(pit->worker_task);
 750         kfree(pit);
 751         return NULL;
 752 }
 753
 754 void kvm_free_pit(struct kvm *kvm)
 755 {
 756         struct hrtimer *timer;
 757
 758         if (kvm->arch.vpit) {
 759                 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &kvm->arch.vpit->dev);
 760                 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS,
 761                                               &kvm->arch.vpit->speaker_dev);
 762                 kvm_unregister_irq_mask_notifier(kvm, 0,
 763                                                &kvm->arch.vpit->mask_notifier);
 764                 kvm_unregister_irq_ack_notifier(kvm,
 765                                 &kvm->arch.vpit->pit_state.irq_ack_notifier);
 766                 mutex_lock(&kvm->arch.vpit->pit_state.lock);
 767                 timer = &kvm->arch.vpit->pit_state.timer;
 768                 hrtimer_cancel(timer);
 769                 flush_kthread_work(&kvm->arch.vpit->expired);
 770                 kthread_stop(kvm->arch.vpit->worker_task);
 771                 kvm_free_irq_source_id(kvm, kvm->arch.vpit->irq_source_id);
 772                 mutex_unlock(&kvm->arch.vpit->pit_state.lock);
 773                 kfree(kvm->arch.vpit);
 774         }
 775 }