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 /* Compute with 96 bit intermediate result: (a*b)/c */
  55 static u64 muldiv64(u64 a, u32 b, u32 c)
  56 {
  57         union {
  58                 u64 ll;
  59                 struct {
  60                         u32 low, high;
  61                 } l;
  62         } u, res;
  63         u64 rl, rh;
  64
  65         u.ll = a;
  66         rl = (u64)u.l.low * (u64)b;
  67         rh = (u64)u.l.high * (u64)b;
  68         rh += (rl >> 32);
  69         res.l.high = div64_u64(rh, c);
  70         res.l.low = div64_u64(((mod_64(rh, c) << 32) + (rl & 0xffffffff)), c);
  71         return res.ll;
  72 }
  73
  74 static void pit_set_gate(struct kvm *kvm, int channel, u32 val)
  75 {
  76         struct kvm_kpit_channel_state *c =
  77                 &kvm->arch.vpit->pit_state.channels[channel];
  78
  79         WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
  80
  81         switch (c->mode) {
  82         default:
  83         case 0:
  84         case 4:
  85                 /* XXX: just disable/enable counting */
  86                 break;
  87         case 1:
  88         case 2:
  89         case 3:
  90         case 5:
  91                 /* Restart counting on rising edge. */
  92                 if (c->gate < val)
  93                         c->count_load_time = ktime_get();
  94                 break;
  95         }
  96
  97         c->gate = val;
  98 }
  99
 100 static int pit_get_gate(struct kvm *kvm, int channel)
 101 {
 102         WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 103
 104         return kvm->arch.vpit->pit_state.channels[channel].gate;
 105 }
 106
 107 static s64 __kpit_elapsed(struct kvm *kvm)
 108 {
 109         s64 elapsed;
 110         ktime_t remaining;
 111         struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
 112
 113         if (!ps->period)
 114                 return 0;
 115
 116         /*
 117          * The Counter does not stop when it reaches zero. In
 118          * Modes 0, 1, 4, and 5 the Counter ``wraps around'' to
 119          * the highest count, either FFFF hex for binary counting
 120          * or 9999 for BCD counting, and continues counting.
 121          * Modes 2 and 3 are periodic; the Counter reloads
 122          * itself with the initial count and continues counting
 123          * from there.
 124          */
 125         remaining = hrtimer_get_remaining(&ps->timer);
 126         elapsed = ps->period - ktime_to_ns(remaining);
 127
 128         return elapsed;
 129 }
 130
 131 static s64 kpit_elapsed(struct kvm *kvm, struct kvm_kpit_channel_state *c,
 132                         int channel)
 133 {
 134         if (channel == 0)
 135                 return __kpit_elapsed(kvm);
 136
 137         return ktime_to_ns(ktime_sub(ktime_get(), c->count_load_time));
 138 }
 139
 140 static int pit_get_count(struct kvm *kvm, int channel)
 141 {
 142         struct kvm_kpit_channel_state *c =
 143                 &kvm->arch.vpit->pit_state.channels[channel];
 144         s64 d, t;
 145         int counter;
 146
 147         WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 148
 149         t = kpit_elapsed(kvm, c, channel);
 150         d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC);
 151
 152         switch (c->mode) {
 153         case 0:
 154         case 1:
 155         case 4:
 156         case 5:
 157                 counter = (c->count - d) & 0xffff;
 158                 break;
 159         case 3:
 160                 /* XXX: may be incorrect for odd counts */
 161                 counter = c->count - (mod_64((2 * d), c->count));
 162                 break;
 163         default:
 164                 counter = c->count - mod_64(d, c->count);
 165                 break;
 166         }
 167         return counter;
 168 }
 169
 170 static int pit_get_out(struct kvm *kvm, int channel)
 171 {
 172         struct kvm_kpit_channel_state *c =
 173                 &kvm->arch.vpit->pit_state.channels[channel];
 174         s64 d, t;
 175         int out;
 176
 177         WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 178
 179         t = kpit_elapsed(kvm, c, channel);
 180         d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC);
 181
 182         switch (c->mode) {
 183         default:
 184         case 0:
 185                 out = (d >= c->count);
 186                 break;
 187         case 1:
 188                 out = (d < c->count);
 189                 break;
 190         case 2:
 191                 out = ((mod_64(d, c->count) == 0) && (d != 0));
 192                 break;
 193         case 3:
 194                 out = (mod_64(d, c->count) < ((c->count + 1) >> 1));
 195                 break;
 196         case 4:
 197         case 5:
 198                 out = (d == c->count);
 199                 break;
 200         }
 201
 202         return out;
 203 }
 204
 205 static void pit_latch_count(struct kvm *kvm, int channel)
 206 {
 207         struct kvm_kpit_channel_state *c =
 208                 &kvm->arch.vpit->pit_state.channels[channel];
 209
 210         WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 211
 212         if (!c->count_latched) {
 213                 c->latched_count = pit_get_count(kvm, channel);
 214                 c->count_latched = c->rw_mode;
 215         }
 216 }
 217
 218 static void pit_latch_status(struct kvm *kvm, int channel)
 219 {
 220         struct kvm_kpit_channel_state *c =
 221                 &kvm->arch.vpit->pit_state.channels[channel];
 222
 223         WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 224
 225         if (!c->status_latched) {
 226                 /* TODO: Return NULL COUNT (bit 6). */
 227                 c->status = ((pit_get_out(kvm, channel) << 7) |
 228                                 (c->rw_mode << 4) |
 229                                 (c->mode << 1) |
 230                                 c->bcd);
 231                 c->status_latched = 1;
 232         }
 233 }
 234
 235 static void kvm_pit_ack_irq(struct kvm_irq_ack_notifier *kian)
 236 {
 237         struct kvm_kpit_state *ps = container_of(kian, struct kvm_kpit_state,
 238                                                  irq_ack_notifier);
 239         int value;
 240
 241         spin_lock(&ps->inject_lock);
 242         value = atomic_dec_return(&ps->pending);
 243         if (value < 0)
 244                 /* spurious acks can be generated if, for example, the
 245                  * PIC is being reset.  Handle it gracefully here
 246                  */
 247                 atomic_inc(&ps->pending);
 248         else if (value > 0 && ps->reinject)
 249                 /* in this case, we had multiple outstanding pit interrupts
 250                  * that we needed to inject.  Reinject
 251                  */
 252                 queue_kthread_work(&ps->pit->worker, &ps->pit->expired);
 253         ps->irq_ack = 1;
 254         spin_unlock(&ps->inject_lock);
 255 }
 256
 257 void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu)
 258 {
 259         struct kvm_pit *pit = vcpu->kvm->arch.vpit;
 260         struct hrtimer *timer;
 261
 262         if (!kvm_vcpu_is_bsp(vcpu) || !pit)
 263                 return;
 264
 265         timer = &pit->pit_state.timer;
 266         mutex_lock(&pit->pit_state.lock);
 267         if (hrtimer_cancel(timer))
 268                 hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 269         mutex_unlock(&pit->pit_state.lock);
 270 }
 271
 272 static void destroy_pit_timer(struct kvm_pit *pit)
 273 {
 274         hrtimer_cancel(&pit->pit_state.timer);
 275         flush_kthread_work(&pit->expired);
 276 }
 277
 278 static void pit_do_work(struct kthread_work *work)
 279 {
 280         struct kvm_pit *pit = container_of(work, struct kvm_pit, expired);
 281         struct kvm *kvm = pit->kvm;
 282         struct kvm_vcpu *vcpu;
 283         int i;
 284         struct kvm_kpit_state *ps = &pit->pit_state;
 285         int inject = 0;
 286
 287         /* Try to inject pending interrupts when
 288          * last one has been acked.
 289          */
 290         spin_lock(&ps->inject_lock);
 291         if (!ps->reinject)
 292                 inject = 1;
 293         else if (ps->irq_ack) {
 294                 ps->irq_ack = 0;
 295                 inject = 1;
 296         }
 297         spin_unlock(&ps->inject_lock);
 298         if (inject) {
 299                 kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 1, false);
 300                 kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 0, false);
 301
 302                 /*
 303                  * Provides NMI watchdog support via Virtual Wire mode.
 304                  * The route is: PIT -> PIC -> LVT0 in NMI mode.
 305                  *
 306                  * Note: Our Virtual Wire implementation is simplified, only
 307                  * propagating PIT interrupts to all VCPUs when they have set
 308                  * LVT0 to NMI delivery. Other PIC interrupts are just sent to
 309                  * VCPU0, and only if its LVT0 is in EXTINT mode.
 310                  */
 311                 if (atomic_read(&kvm->arch.vapics_in_nmi_mode) > 0)
 312                         kvm_for_each_vcpu(i, vcpu, kvm)
 313                                 kvm_apic_nmi_wd_deliver(vcpu);
 314         }
 315 }
 316
 317 static enum hrtimer_restart pit_timer_fn(struct hrtimer *data)
 318 {
 319         struct kvm_kpit_state *ps = container_of(data, struct kvm_kpit_state, timer);
 320         struct kvm_pit *pt = ps->kvm->arch.vpit;
 321
 322         if (ps->reinject)
 323                 atomic_inc(&ps->pending);
 324
 325         queue_kthread_work(&pt->worker, &pt->expired);
 326
 327         if (ps->is_periodic) {
 328                 hrtimer_add_expires_ns(&ps->timer, ps->period);
 329                 return HRTIMER_RESTART;
 330         } else
 331                 return HRTIMER_NORESTART;
 332 }
 333
 334 static void create_pit_timer(struct kvm *kvm, u32 val, int is_period)
 335 {
 336         struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
 337         s64 interval;
 338
 339         if (!ioapic_in_kernel(kvm) ||
 340             ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)
 341                 return;
 342
 343         interval = muldiv64(val, NSEC_PER_SEC, KVM_PIT_FREQ);
 344
 345         pr_debug("create pit timer, interval is %llu nsec\n", interval);
 346
 347         /* TODO The new value only affected after the retriggered */
 348         hrtimer_cancel(&ps->timer);
 349         flush_kthread_work(&ps->pit->expired);
 350         ps->period = interval;
 351         ps->is_periodic = is_period;
 352
 353         ps->timer.function = pit_timer_fn;
 354         ps->kvm = ps->pit->kvm;
 355
 356         atomic_set(&ps->pending, 0);
 357         ps->irq_ack = 1;
 358
 359         /*
 360          * Do not allow the guest to program periodic timers with small
 361          * interval, since the hrtimers are not throttled by the host
 362          * scheduler.
 363          */
 364         if (ps->is_periodic) {
 365                 s64 min_period = min_timer_period_us * 1000LL;
 366
 367                 if (ps->period < min_period) {
 368                         pr_info_ratelimited(
 369                             "kvm: requested %lld ns "
 370                             "i8254 timer period limited to %lld ns\n",
 371                             ps->period, min_period);
 372                         ps->period = min_period;
 373                 }
 374         }
 375
 376         hrtimer_start(&ps->timer, ktime_add_ns(ktime_get(), interval),
 377                       HRTIMER_MODE_ABS);
 378 }
 379
 380 static void pit_load_count(struct kvm *kvm, int channel, u32 val)
 381 {
 382         struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
 383
 384         WARN_ON(!mutex_is_locked(&ps->lock));
 385
 386         pr_debug("load_count val is %d, channel is %d\n", val, channel);
 387
 388         /*
 389          * The largest possible initial count is 0; this is equivalent
 390          * to 216 for binary counting and 104 for BCD counting.
 391          */
 392         if (val == 0)
 393                 val = 0x10000;
 394
 395         ps->channels[channel].count = val;
 396
 397         if (channel != 0) {
 398                 ps->channels[channel].count_load_time = ktime_get();
 399                 return;
 400         }
 401
 402         /* Two types of timer
 403          * mode 1 is one shot, mode 2 is period, otherwise del timer */
 404         switch (ps->channels[0].mode) {
 405         case 0:
 406         case 1:
 407         /* FIXME: enhance mode 4 precision */
 408         case 4:
 409                 create_pit_timer(kvm, val, 0);
 410                 break;
 411         case 2:
 412         case 3:
 413                 create_pit_timer(kvm, val, 1);
 414                 break;
 415         default:
 416                 destroy_pit_timer(kvm->arch.vpit);
 417         }
 418 }
 419
 420 void kvm_pit_load_count(struct kvm *kvm, int channel, u32 val, int hpet_legacy_start)
 421 {
 422         u8 saved_mode;
 423         if (hpet_legacy_start) {
 424                 /* save existing mode for later reenablement */
 425                 WARN_ON(channel != 0);
 426                 saved_mode = kvm->arch.vpit->pit_state.channels[0].mode;
 427                 kvm->arch.vpit->pit_state.channels[0].mode = 0xff; /* disable timer */
 428                 pit_load_count(kvm, channel, val);
 429                 kvm->arch.vpit->pit_state.channels[0].mode = saved_mode;
 430         } else {
 431                 pit_load_count(kvm, channel, val);
 432         }
 433 }
 434
 435 static inline struct kvm_pit *dev_to_pit(struct kvm_io_device *dev)
 436 {
 437         return container_of(dev, struct kvm_pit, dev);
 438 }
 439
 440 static inline struct kvm_pit *speaker_to_pit(struct kvm_io_device *dev)
 441 {
 442         return container_of(dev, struct kvm_pit, speaker_dev);
 443 }
 444
 445 static inline int pit_in_range(gpa_t addr)
 446 {
 447         return ((addr >= KVM_PIT_BASE_ADDRESS) &&
 448                 (addr < KVM_PIT_BASE_ADDRESS + KVM_PIT_MEM_LENGTH));
 449 }
 450
 451 static int pit_ioport_write(struct kvm_vcpu *vcpu,
 452                                 struct kvm_io_device *this,
 453                             gpa_t addr, int len, const void *data)
 454 {
 455         struct kvm_pit *pit = dev_to_pit(this);
 456         struct kvm_kpit_state *pit_state = &pit->pit_state;
 457         struct kvm *kvm = pit->kvm;
 458         int channel, access;
 459         struct kvm_kpit_channel_state *s;
 460         u32 val = *(u32 *) data;
 461         if (!pit_in_range(addr))
 462                 return -EOPNOTSUPP;
 463
 464         val  &= 0xff;
 465         addr &= KVM_PIT_CHANNEL_MASK;
 466
 467         mutex_lock(&pit_state->lock);
 468
 469         if (val != 0)
 470                 pr_debug("write addr is 0x%x, len is %d, val is 0x%x\n",
 471                          (unsigned int)addr, len, val);
 472
 473         if (addr == 3) {
 474                 channel = val >> 6;
 475                 if (channel == 3) {
 476                         /* Read-Back Command. */
 477                         for (channel = 0; channel < 3; channel++) {
 478                                 s = &pit_state->channels[channel];
 479                                 if (val & (2 << channel)) {
 480                                         if (!(val & 0x20))
 481                                                 pit_latch_count(kvm, channel);
 482                                         if (!(val & 0x10))
 483                                                 pit_latch_status(kvm, channel);
 484                                 }
 485                         }
 486                 } else {
 487                         /* Select Counter <channel>. */
 488                         s = &pit_state->channels[channel];
 489                         access = (val >> 4) & KVM_PIT_CHANNEL_MASK;
 490                         if (access == 0) {
 491                                 pit_latch_count(kvm, channel);
 492                         } else {
 493                                 s->rw_mode = access;
 494                                 s->read_state = access;
 495                                 s->write_state = access;
 496                                 s->mode = (val >> 1) & 7;
 497                                 if (s->mode > 5)
 498                                         s->mode -= 4;
 499                                 s->bcd = val & 1;
 500                         }
 501                 }
 502         } else {
 503                 /* Write Count. */
 504                 s = &pit_state->channels[addr];
 505                 switch (s->write_state) {
 506                 default:
 507                 case RW_STATE_LSB:
 508                         pit_load_count(kvm, addr, val);
 509                         break;
 510                 case RW_STATE_MSB:
 511                         pit_load_count(kvm, addr, val << 8);
 512                         break;
 513                 case RW_STATE_WORD0:
 514                         s->write_latch = val;
 515                         s->write_state = RW_STATE_WORD1;
 516                         break;
 517                 case RW_STATE_WORD1:
 518                         pit_load_count(kvm, addr, s->write_latch | (val << 8));
 519                         s->write_state = RW_STATE_WORD0;
 520                         break;
 521                 }
 522         }
 523
 524         mutex_unlock(&pit_state->lock);
 525         return 0;
 526 }
 527
 528 static int pit_ioport_read(struct kvm_vcpu *vcpu,
 529                            struct kvm_io_device *this,
 530                            gpa_t addr, int len, void *data)
 531 {
 532         struct kvm_pit *pit = dev_to_pit(this);
 533         struct kvm_kpit_state *pit_state = &pit->pit_state;
 534         struct kvm *kvm = pit->kvm;
 535         int ret, count;
 536         struct kvm_kpit_channel_state *s;
 537         if (!pit_in_range(addr))
 538                 return -EOPNOTSUPP;
 539
 540         addr &= KVM_PIT_CHANNEL_MASK;
 541         if (addr == 3)
 542                 return 0;
 543
 544         s = &pit_state->channels[addr];
 545
 546         mutex_lock(&pit_state->lock);
 547
 548         if (s->status_latched) {
 549                 s->status_latched = 0;
 550                 ret = s->status;
 551         } else if (s->count_latched) {
 552                 switch (s->count_latched) {
 553                 default:
 554                 case RW_STATE_LSB:
 555                         ret = s->latched_count & 0xff;
 556                         s->count_latched = 0;
 557                         break;
 558                 case RW_STATE_MSB:
 559                         ret = s->latched_count >> 8;
 560                         s->count_latched = 0;
 561                         break;
 562                 case RW_STATE_WORD0:
 563                         ret = s->latched_count & 0xff;
 564                         s->count_latched = RW_STATE_MSB;
 565                         break;
 566                 }
 567         } else {
 568                 switch (s->read_state) {
 569                 default:
 570                 case RW_STATE_LSB:
 571                         count = pit_get_count(kvm, addr);
 572                         ret = count & 0xff;
 573                         break;
 574                 case RW_STATE_MSB:
 575                         count = pit_get_count(kvm, addr);
 576                         ret = (count >> 8) & 0xff;
 577                         break;
 578                 case RW_STATE_WORD0:
 579                         count = pit_get_count(kvm, addr);
 580                         ret = count & 0xff;
 581                         s->read_state = RW_STATE_WORD1;
 582                         break;
 583                 case RW_STATE_WORD1:
 584                         count = pit_get_count(kvm, addr);
 585                         ret = (count >> 8) & 0xff;
 586                         s->read_state = RW_STATE_WORD0;
 587                         break;
 588                 }
 589         }
 590
 591         if (len > sizeof(ret))
 592                 len = sizeof(ret);
 593         memcpy(data, (char *)&ret, len);
 594
 595         mutex_unlock(&pit_state->lock);
 596         return 0;
 597 }
 598
 599 static int speaker_ioport_write(struct kvm_vcpu *vcpu,
 600                                 struct kvm_io_device *this,
 601                                 gpa_t addr, int len, const void *data)
 602 {
 603         struct kvm_pit *pit = speaker_to_pit(this);
 604         struct kvm_kpit_state *pit_state = &pit->pit_state;
 605         struct kvm *kvm = pit->kvm;
 606         u32 val = *(u32 *) data;
 607         if (addr != KVM_SPEAKER_BASE_ADDRESS)
 608                 return -EOPNOTSUPP;
 609
 610         mutex_lock(&pit_state->lock);
 611         pit_state->speaker_data_on = (val >> 1) & 1;
 612         pit_set_gate(kvm, 2, val & 1);
 613         mutex_unlock(&pit_state->lock);
 614         return 0;
 615 }
 616
 617 static int speaker_ioport_read(struct kvm_vcpu *vcpu,
 618                                    struct kvm_io_device *this,
 619                                    gpa_t addr, int len, void *data)
 620 {
 621         struct kvm_pit *pit = speaker_to_pit(this);
 622         struct kvm_kpit_state *pit_state = &pit->pit_state;
 623         struct kvm *kvm = pit->kvm;
 624         unsigned int refresh_clock;
 625         int ret;
 626         if (addr != KVM_SPEAKER_BASE_ADDRESS)
 627                 return -EOPNOTSUPP;
 628
 629         /* Refresh clock toggles at about 15us. We approximate as 2^14ns. */
 630         refresh_clock = ((unsigned int)ktime_to_ns(ktime_get()) >> 14) & 1;
 631
 632         mutex_lock(&pit_state->lock);
 633         ret = ((pit_state->speaker_data_on << 1) | pit_get_gate(kvm, 2) |
 634                 (pit_get_out(kvm, 2) << 5) | (refresh_clock << 4));
 635         if (len > sizeof(ret))
 636                 len = sizeof(ret);
 637         memcpy(data, (char *)&ret, len);
 638         mutex_unlock(&pit_state->lock);
 639         return 0;
 640 }
 641
 642 void kvm_pit_reset(struct kvm_pit *pit)
 643 {
 644         int i;
 645         struct kvm_kpit_channel_state *c;
 646
 647         mutex_lock(&pit->pit_state.lock);
 648         pit->pit_state.flags = 0;
 649         for (i = 0; i < 3; i++) {
 650                 c = &pit->pit_state.channels[i];
 651                 c->mode = 0xff;
 652                 c->gate = (i != 2);
 653                 pit_load_count(pit->kvm, i, 0);
 654         }
 655         mutex_unlock(&pit->pit_state.lock);
 656
 657         atomic_set(&pit->pit_state.pending, 0);
 658         pit->pit_state.irq_ack = 1;
 659 }
 660
 661 static void pit_mask_notifer(struct kvm_irq_mask_notifier *kimn, bool mask)
 662 {
 663         struct kvm_pit *pit = container_of(kimn, struct kvm_pit, mask_notifier);
 664
 665         if (!mask) {
 666                 atomic_set(&pit->pit_state.pending, 0);
 667                 pit->pit_state.irq_ack = 1;
 668         }
 669 }
 670
 671 static const struct kvm_io_device_ops pit_dev_ops = {
 672         .read     = pit_ioport_read,
 673         .write    = pit_ioport_write,
 674 };
 675
 676 static const struct kvm_io_device_ops speaker_dev_ops = {
 677         .read     = speaker_ioport_read,
 678         .write    = speaker_ioport_write,
 679 };
 680
 681 /* Caller must hold slots_lock */
 682 struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
 683 {
 684         struct kvm_pit *pit;
 685         struct kvm_kpit_state *pit_state;
 686         struct pid *pid;
 687         pid_t pid_nr;
 688         int ret;
 689
 690         pit = kzalloc(sizeof(struct kvm_pit), GFP_KERNEL);
 691         if (!pit)
 692                 return NULL;
 693
 694         pit->irq_source_id = kvm_request_irq_source_id(kvm);
 695         if (pit->irq_source_id < 0) {
 696                 kfree(pit);
 697                 return NULL;
 698         }
 699
 700         mutex_init(&pit->pit_state.lock);
 701         mutex_lock(&pit->pit_state.lock);
 702         spin_lock_init(&pit->pit_state.inject_lock);
 703
 704         pid = get_pid(task_tgid(current));
 705         pid_nr = pid_vnr(pid);
 706         put_pid(pid);
 707
 708         init_kthread_worker(&pit->worker);
 709         pit->worker_task = kthread_run(kthread_worker_fn, &pit->worker,
 710                                        "kvm-pit/%d", pid_nr);
 711         if (IS_ERR(pit->worker_task)) {
 712                 mutex_unlock(&pit->pit_state.lock);
 713                 kvm_free_irq_source_id(kvm, pit->irq_source_id);
 714                 kfree(pit);
 715                 return NULL;
 716         }
 717         init_kthread_work(&pit->expired, pit_do_work);
 718
 719         kvm->arch.vpit = pit;
 720         pit->kvm = kvm;
 721
 722         pit_state = &pit->pit_state;
 723         pit_state->pit = pit;
 724         hrtimer_init(&pit_state->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 725         pit_state->irq_ack_notifier.gsi = 0;
 726         pit_state->irq_ack_notifier.irq_acked = kvm_pit_ack_irq;
 727         kvm_register_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
 728         pit_state->reinject = true;
 729         mutex_unlock(&pit->pit_state.lock);
 730
 731         kvm_pit_reset(pit);
 732
 733         pit->mask_notifier.func = pit_mask_notifer;
 734         kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
 735
 736         kvm_iodevice_init(&pit->dev, &pit_dev_ops);
 737         ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, KVM_PIT_BASE_ADDRESS,
 738                                       KVM_PIT_MEM_LENGTH, &pit->dev);
 739         if (ret < 0)
 740                 goto fail;
 741
 742         if (flags & KVM_PIT_SPEAKER_DUMMY) {
 743                 kvm_iodevice_init(&pit->speaker_dev, &speaker_dev_ops);
 744                 ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS,
 745                                               KVM_SPEAKER_BASE_ADDRESS, 4,
 746                                               &pit->speaker_dev);
 747                 if (ret < 0)
 748                         goto fail_unregister;
 749         }
 750
 751         return pit;
 752
 753 fail_unregister:
 754         kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev);
 755
 756 fail:
 757         kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
 758         kvm_unregister_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
 759         kvm_free_irq_source_id(kvm, pit->irq_source_id);
 760         kthread_stop(pit->worker_task);
 761         kfree(pit);
 762         return NULL;
 763 }
 764
 765 void kvm_free_pit(struct kvm *kvm)
 766 {
 767         struct hrtimer *timer;
 768
 769         if (kvm->arch.vpit) {
 770                 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &kvm->arch.vpit->dev);
 771                 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS,
 772                                               &kvm->arch.vpit->speaker_dev);
 773                 kvm_unregister_irq_mask_notifier(kvm, 0,
 774                                                &kvm->arch.vpit->mask_notifier);
 775                 kvm_unregister_irq_ack_notifier(kvm,
 776                                 &kvm->arch.vpit->pit_state.irq_ack_notifier);
 777                 mutex_lock(&kvm->arch.vpit->pit_state.lock);
 778                 timer = &kvm->arch.vpit->pit_state.timer;
 779                 hrtimer_cancel(timer);
 780                 flush_kthread_work(&kvm->arch.vpit->expired);
 781                 kthread_stop(kvm->arch.vpit->worker_task);
 782                 kvm_free_irq_source_id(kvm, kvm->arch.vpit->irq_source_id);
 783                 mutex_unlock(&kvm->arch.vpit->pit_state.lock);
 784                 kfree(kvm->arch.vpit);
 785         }
 786 }