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 #include <linux/workqueue.h>
  38
  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->pit_timer.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->pit_timer.timer);
 126         elapsed = ps->pit_timer.period - ktime_to_ns(remaining);
 127         elapsed = mod_64(elapsed, ps->pit_timer.period);
 128
 129         return elapsed;
 130 }
 131
 132 static s64 kpit_elapsed(struct kvm *kvm, struct kvm_kpit_channel_state *c,
 133                         int channel)
 134 {
 135         if (channel == 0)
 136                 return __kpit_elapsed(kvm);
 137
 138         return ktime_to_ns(ktime_sub(ktime_get(), c->count_load_time));
 139 }
 140
 141 static int pit_get_count(struct kvm *kvm, int channel)
 142 {
 143         struct kvm_kpit_channel_state *c =
 144                 &kvm->arch.vpit->pit_state.channels[channel];
 145         s64 d, t;
 146         int counter;
 147
 148         WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 149
 150         t = kpit_elapsed(kvm, c, channel);
 151         d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC);
 152
 153         switch (c->mode) {
 154         case 0:
 155         case 1:
 156         case 4:
 157         case 5:
 158                 counter = (c->count - d) & 0xffff;
 159                 break;
 160         case 3:
 161                 /* XXX: may be incorrect for odd counts */
 162                 counter = c->count - (mod_64((2 * d), c->count));
 163                 break;
 164         default:
 165                 counter = c->count - mod_64(d, c->count);
 166                 break;
 167         }
 168         return counter;
 169 }
 170
 171 static int pit_get_out(struct kvm *kvm, int channel)
 172 {
 173         struct kvm_kpit_channel_state *c =
 174                 &kvm->arch.vpit->pit_state.channels[channel];
 175         s64 d, t;
 176         int out;
 177
 178         WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 179
 180         t = kpit_elapsed(kvm, c, channel);
 181         d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC);
 182
 183         switch (c->mode) {
 184         default:
 185         case 0:
 186                 out = (d >= c->count);
 187                 break;
 188         case 1:
 189                 out = (d < c->count);
 190                 break;
 191         case 2:
 192                 out = ((mod_64(d, c->count) == 0) && (d != 0));
 193                 break;
 194         case 3:
 195                 out = (mod_64(d, c->count) < ((c->count + 1) >> 1));
 196                 break;
 197         case 4:
 198         case 5:
 199                 out = (d == c->count);
 200                 break;
 201         }
 202
 203         return out;
 204 }
 205
 206 static void pit_latch_count(struct kvm *kvm, int channel)
 207 {
 208         struct kvm_kpit_channel_state *c =
 209                 &kvm->arch.vpit->pit_state.channels[channel];
 210
 211         WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 212
 213         if (!c->count_latched) {
 214                 c->latched_count = pit_get_count(kvm, channel);
 215                 c->count_latched = c->rw_mode;
 216         }
 217 }
 218
 219 static void pit_latch_status(struct kvm *kvm, int channel)
 220 {
 221         struct kvm_kpit_channel_state *c =
 222                 &kvm->arch.vpit->pit_state.channels[channel];
 223
 224         WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 225
 226         if (!c->status_latched) {
 227                 /* TODO: Return NULL COUNT (bit 6). */
 228                 c->status = ((pit_get_out(kvm, channel) << 7) |
 229                                 (c->rw_mode << 4) |
 230                                 (c->mode << 1) |
 231                                 c->bcd);
 232                 c->status_latched = 1;
 233         }
 234 }
 235
 236 static void kvm_pit_ack_irq(struct kvm_irq_ack_notifier *kian)
 237 {
 238         struct kvm_kpit_state *ps = container_of(kian, struct kvm_kpit_state,
 239                                                  irq_ack_notifier);
 240         int value;
 241
 242         spin_lock(&ps->inject_lock);
 243         value = atomic_dec_return(&ps->pit_timer.pending);
 244         if (value < 0)
 245                 /* spurious acks can be generated if, for example, the
 246                  * PIC is being reset.  Handle it gracefully here
 247                  */
 248                 atomic_inc(&ps->pit_timer.pending);
 249         else if (value > 0)
 250                 /* in this case, we had multiple outstanding pit interrupts
 251                  * that we needed to inject.  Reinject
 252                  */
 253                 queue_work(ps->pit->wq, &ps->pit->expired);
 254         ps->irq_ack = 1;
 255         spin_unlock(&ps->inject_lock);
 256 }
 257
 258 void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu)
 259 {
 260         struct kvm_pit *pit = vcpu->kvm->arch.vpit;
 261         struct hrtimer *timer;
 262
 263         if (!kvm_vcpu_is_bsp(vcpu) || !pit)
 264                 return;
 265
 266         timer = &pit->pit_state.pit_timer.timer;
 267         if (hrtimer_cancel(timer))
 268                 hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 269 }
 270
 271 static void destroy_pit_timer(struct kvm_pit *pit)
 272 {
 273         hrtimer_cancel(&pit->pit_state.pit_timer.timer);
 274         cancel_work_sync(&pit->expired);
 275 }
 276
 277 static bool kpit_is_periodic(struct kvm_timer *ktimer)
 278 {
 279         struct kvm_kpit_state *ps = container_of(ktimer, struct kvm_kpit_state,
 280                                                  pit_timer);
 281         return ps->is_periodic;
 282 }
 283
 284 static struct kvm_timer_ops kpit_ops = {
 285         .is_periodic = kpit_is_periodic,
 286 };
 287
 288 static void pit_do_work(struct work_struct *work)
 289 {
 290         struct kvm_pit *pit = container_of(work, struct kvm_pit, expired);
 291         struct kvm *kvm = pit->kvm;
 292         struct kvm_vcpu *vcpu;
 293         int i;
 294         struct kvm_kpit_state *ps = &pit->pit_state;
 295         int inject = 0;
 296
 297         /* Try to inject pending interrupts when
 298          * last one has been acked.
 299          */
 300         spin_lock(&ps->inject_lock);
 301         if (ps->irq_ack) {
 302                 ps->irq_ack = 0;
 303                 inject = 1;
 304         }
 305         spin_unlock(&ps->inject_lock);
 306         if (inject) {
 307                 kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 1);
 308                 kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 0);
 309
 310                 /*
 311                  * Provides NMI watchdog support via Virtual Wire mode.
 312                  * The route is: PIT -> PIC -> LVT0 in NMI mode.
 313                  *
 314                  * Note: Our Virtual Wire implementation is simplified, only
 315                  * propagating PIT interrupts to all VCPUs when they have set
 316                  * LVT0 to NMI delivery. Other PIC interrupts are just sent to
 317                  * VCPU0, and only if its LVT0 is in EXTINT mode.
 318                  */
 319                 if (kvm->arch.vapics_in_nmi_mode > 0)
 320                         kvm_for_each_vcpu(i, vcpu, kvm)
 321                                 kvm_apic_nmi_wd_deliver(vcpu);
 322         }
 323 }
 324
 325 static enum hrtimer_restart pit_timer_fn(struct hrtimer *data)
 326 {
 327         struct kvm_timer *ktimer = container_of(data, struct kvm_timer, timer);
 328         struct kvm_pit *pt = ktimer->kvm->arch.vpit;
 329
 330         if (ktimer->reinject || !atomic_read(&ktimer->pending)) {
 331                 atomic_inc(&ktimer->pending);
 332                 queue_work(pt->wq, &pt->expired);
 333         }
 334
 335         if (ktimer->t_ops->is_periodic(ktimer)) {
 336                 hrtimer_add_expires_ns(&ktimer->timer, ktimer->period);
 337                 return HRTIMER_RESTART;
 338         } else
 339                 return HRTIMER_NORESTART;
 340 }
 341
 342 static void create_pit_timer(struct kvm *kvm, u32 val, int is_period)
 343 {
 344         struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
 345         struct kvm_timer *pt = &ps->pit_timer;
 346         s64 interval;
 347
 348         if (!irqchip_in_kernel(kvm))
 349                 return;
 350
 351         interval = muldiv64(val, NSEC_PER_SEC, KVM_PIT_FREQ);
 352
 353         pr_debug("create pit timer, interval is %llu nsec\n", interval);
 354
 355         /* TODO The new value only affected after the retriggered */
 356         hrtimer_cancel(&pt->timer);
 357         cancel_work_sync(&ps->pit->expired);
 358         pt->period = interval;
 359         ps->is_periodic = is_period;
 360
 361         pt->timer.function = pit_timer_fn;
 362         pt->t_ops = &kpit_ops;
 363         pt->kvm = ps->pit->kvm;
 364
 365         atomic_set(&pt->pending, 0);
 366         ps->irq_ack = 1;
 367
 368         /*
 369          * Do not allow the guest to program periodic timers with small
 370          * interval, since the hrtimers are not throttled by the host
 371          * scheduler.
 372          */
 373         if (ps->is_periodic) {
 374                 s64 min_period = min_timer_period_us * 1000LL;
 375
 376                 if (pt->period < min_period) {
 377                         pr_info_ratelimited(
 378                             "kvm: requested %lld ns "
 379                             "i8254 timer period limited to %lld ns\n",
 380                             pt->period, min_period);
 381                         pt->period = min_period;
 382                 }
 383         }
 384
 385         hrtimer_start(&pt->timer, ktime_add_ns(ktime_get(), interval),
 386                       HRTIMER_MODE_ABS);
 387 }
 388
 389 static void pit_load_count(struct kvm *kvm, int channel, u32 val)
 390 {
 391         struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
 392
 393         WARN_ON(!mutex_is_locked(&ps->lock));
 394
 395         pr_debug("load_count val is %d, channel is %d\n", val, channel);
 396
 397         /*
 398          * The largest possible initial count is 0; this is equivalent
 399          * to 216 for binary counting and 104 for BCD counting.
 400          */
 401         if (val == 0)
 402                 val = 0x10000;
 403
 404         ps->channels[channel].count = val;
 405
 406         if (channel != 0) {
 407                 ps->channels[channel].count_load_time = ktime_get();
 408                 return;
 409         }
 410
 411         /* Two types of timer
 412          * mode 1 is one shot, mode 2 is period, otherwise del timer */
 413         switch (ps->channels[0].mode) {
 414         case 0:
 415         case 1:
 416         /* FIXME: enhance mode 4 precision */
 417         case 4:
 418                 if (!(ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)) {
 419                         create_pit_timer(kvm, val, 0);
 420                 }
 421                 break;
 422         case 2:
 423         case 3:
 424                 if (!(ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)){
 425                         create_pit_timer(kvm, val, 1);
 426                 }
 427                 break;
 428         default:
 429                 destroy_pit_timer(kvm->arch.vpit);
 430         }
 431 }
 432
 433 void kvm_pit_load_count(struct kvm *kvm, int channel, u32 val, int hpet_legacy_start)
 434 {
 435         u8 saved_mode;
 436         if (hpet_legacy_start) {
 437                 /* save existing mode for later reenablement */
 438                 saved_mode = kvm->arch.vpit->pit_state.channels[0].mode;
 439                 kvm->arch.vpit->pit_state.channels[0].mode = 0xff; /* disable timer */
 440                 pit_load_count(kvm, channel, val);
 441                 kvm->arch.vpit->pit_state.channels[0].mode = saved_mode;
 442         } else {
 443                 pit_load_count(kvm, channel, val);
 444         }
 445 }
 446
 447 static inline struct kvm_pit *dev_to_pit(struct kvm_io_device *dev)
 448 {
 449         return container_of(dev, struct kvm_pit, dev);
 450 }
 451
 452 static inline struct kvm_pit *speaker_to_pit(struct kvm_io_device *dev)
 453 {
 454         return container_of(dev, struct kvm_pit, speaker_dev);
 455 }
 456
 457 static inline int pit_in_range(gpa_t addr)
 458 {
 459         return ((addr >= KVM_PIT_BASE_ADDRESS) &&
 460                 (addr < KVM_PIT_BASE_ADDRESS + KVM_PIT_MEM_LENGTH));
 461 }
 462
 463 static int pit_ioport_write(struct kvm_io_device *this,
 464                             gpa_t addr, int len, const void *data)
 465 {
 466         struct kvm_pit *pit = dev_to_pit(this);
 467         struct kvm_kpit_state *pit_state = &pit->pit_state;
 468         struct kvm *kvm = pit->kvm;
 469         int channel, access;
 470         struct kvm_kpit_channel_state *s;
 471         u32 val = *(u32 *) data;
 472         if (!pit_in_range(addr))
 473                 return -EOPNOTSUPP;
 474
 475         val  &= 0xff;
 476         addr &= KVM_PIT_CHANNEL_MASK;
 477
 478         mutex_lock(&pit_state->lock);
 479
 480         if (val != 0)
 481                 pr_debug("write addr is 0x%x, len is %d, val is 0x%x\n",
 482                          (unsigned int)addr, len, val);
 483
 484         if (addr == 3) {
 485                 channel = val >> 6;
 486                 if (channel == 3) {
 487                         /* Read-Back Command. */
 488                         for (channel = 0; channel < 3; channel++) {
 489                                 s = &pit_state->channels[channel];
 490                                 if (val & (2 << channel)) {
 491                                         if (!(val & 0x20))
 492                                                 pit_latch_count(kvm, channel);
 493                                         if (!(val & 0x10))
 494                                                 pit_latch_status(kvm, channel);
 495                                 }
 496                         }
 497                 } else {
 498                         /* Select Counter <channel>. */
 499                         s = &pit_state->channels[channel];
 500                         access = (val >> 4) & KVM_PIT_CHANNEL_MASK;
 501                         if (access == 0) {
 502                                 pit_latch_count(kvm, channel);
 503                         } else {
 504                                 s->rw_mode = access;
 505                                 s->read_state = access;
 506                                 s->write_state = access;
 507                                 s->mode = (val >> 1) & 7;
 508                                 if (s->mode > 5)
 509                                         s->mode -= 4;
 510                                 s->bcd = val & 1;
 511                         }
 512                 }
 513         } else {
 514                 /* Write Count. */
 515                 s = &pit_state->channels[addr];
 516                 switch (s->write_state) {
 517                 default:
 518                 case RW_STATE_LSB:
 519                         pit_load_count(kvm, addr, val);
 520                         break;
 521                 case RW_STATE_MSB:
 522                         pit_load_count(kvm, addr, val << 8);
 523                         break;
 524                 case RW_STATE_WORD0:
 525                         s->write_latch = val;
 526                         s->write_state = RW_STATE_WORD1;
 527                         break;
 528                 case RW_STATE_WORD1:
 529                         pit_load_count(kvm, addr, s->write_latch | (val << 8));
 530                         s->write_state = RW_STATE_WORD0;
 531                         break;
 532                 }
 533         }
 534
 535         mutex_unlock(&pit_state->lock);
 536         return 0;
 537 }
 538
 539 static int pit_ioport_read(struct kvm_io_device *this,
 540                            gpa_t addr, int len, void *data)
 541 {
 542         struct kvm_pit *pit = dev_to_pit(this);
 543         struct kvm_kpit_state *pit_state = &pit->pit_state;
 544         struct kvm *kvm = pit->kvm;
 545         int ret, count;
 546         struct kvm_kpit_channel_state *s;
 547         if (!pit_in_range(addr))
 548                 return -EOPNOTSUPP;
 549
 550         addr &= KVM_PIT_CHANNEL_MASK;
 551         if (addr == 3)
 552                 return 0;
 553
 554         s = &pit_state->channels[addr];
 555
 556         mutex_lock(&pit_state->lock);
 557
 558         if (s->status_latched) {
 559                 s->status_latched = 0;
 560                 ret = s->status;
 561         } else if (s->count_latched) {
 562                 switch (s->count_latched) {
 563                 default:
 564                 case RW_STATE_LSB:
 565                         ret = s->latched_count & 0xff;
 566                         s->count_latched = 0;
 567                         break;
 568                 case RW_STATE_MSB:
 569                         ret = s->latched_count >> 8;
 570                         s->count_latched = 0;
 571                         break;
 572                 case RW_STATE_WORD0:
 573                         ret = s->latched_count & 0xff;
 574                         s->count_latched = RW_STATE_MSB;
 575                         break;
 576                 }
 577         } else {
 578                 switch (s->read_state) {
 579                 default:
 580                 case RW_STATE_LSB:
 581                         count = pit_get_count(kvm, addr);
 582                         ret = count & 0xff;
 583                         break;
 584                 case RW_STATE_MSB:
 585                         count = pit_get_count(kvm, addr);
 586                         ret = (count >> 8) & 0xff;
 587                         break;
 588                 case RW_STATE_WORD0:
 589                         count = pit_get_count(kvm, addr);
 590                         ret = count & 0xff;
 591                         s->read_state = RW_STATE_WORD1;
 592                         break;
 593                 case RW_STATE_WORD1:
 594                         count = pit_get_count(kvm, addr);
 595                         ret = (count >> 8) & 0xff;
 596                         s->read_state = RW_STATE_WORD0;
 597                         break;
 598                 }
 599         }
 600
 601         if (len > sizeof(ret))
 602                 len = sizeof(ret);
 603         memcpy(data, (char *)&ret, len);
 604
 605         mutex_unlock(&pit_state->lock);
 606         return 0;
 607 }
 608
 609 static int speaker_ioport_write(struct kvm_io_device *this,
 610                                 gpa_t addr, int len, const void *data)
 611 {
 612         struct kvm_pit *pit = speaker_to_pit(this);
 613         struct kvm_kpit_state *pit_state = &pit->pit_state;
 614         struct kvm *kvm = pit->kvm;
 615         u32 val = *(u32 *) data;
 616         if (addr != KVM_SPEAKER_BASE_ADDRESS)
 617                 return -EOPNOTSUPP;
 618
 619         mutex_lock(&pit_state->lock);
 620         pit_state->speaker_data_on = (val >> 1) & 1;
 621         pit_set_gate(kvm, 2, val & 1);
 622         mutex_unlock(&pit_state->lock);
 623         return 0;
 624 }
 625
 626 static int speaker_ioport_read(struct kvm_io_device *this,
 627                                gpa_t addr, int len, void *data)
 628 {
 629         struct kvm_pit *pit = speaker_to_pit(this);
 630         struct kvm_kpit_state *pit_state = &pit->pit_state;
 631         struct kvm *kvm = pit->kvm;
 632         unsigned int refresh_clock;
 633         int ret;
 634         if (addr != KVM_SPEAKER_BASE_ADDRESS)
 635                 return -EOPNOTSUPP;
 636
 637         /* Refresh clock toggles at about 15us. We approximate as 2^14ns. */
 638         refresh_clock = ((unsigned int)ktime_to_ns(ktime_get()) >> 14) & 1;
 639
 640         mutex_lock(&pit_state->lock);
 641         ret = ((pit_state->speaker_data_on << 1) | pit_get_gate(kvm, 2) |
 642                 (pit_get_out(kvm, 2) << 5) | (refresh_clock << 4));
 643         if (len > sizeof(ret))
 644                 len = sizeof(ret);
 645         memcpy(data, (char *)&ret, len);
 646         mutex_unlock(&pit_state->lock);
 647         return 0;
 648 }
 649
 650 void kvm_pit_reset(struct kvm_pit *pit)
 651 {
 652         int i;
 653         struct kvm_kpit_channel_state *c;
 654
 655         mutex_lock(&pit->pit_state.lock);
 656         pit->pit_state.flags = 0;
 657         for (i = 0; i < 3; i++) {
 658                 c = &pit->pit_state.channels[i];
 659                 c->mode = 0xff;
 660                 c->gate = (i != 2);
 661                 pit_load_count(pit->kvm, i, 0);
 662         }
 663         mutex_unlock(&pit->pit_state.lock);
 664
 665         atomic_set(&pit->pit_state.pit_timer.pending, 0);
 666         pit->pit_state.irq_ack = 1;
 667 }
 668
 669 static void pit_mask_notifer(struct kvm_irq_mask_notifier *kimn, bool mask)
 670 {
 671         struct kvm_pit *pit = container_of(kimn, struct kvm_pit, mask_notifier);
 672
 673         if (!mask) {
 674                 atomic_set(&pit->pit_state.pit_timer.pending, 0);
 675                 pit->pit_state.irq_ack = 1;
 676         }
 677 }
 678
 679 static const struct kvm_io_device_ops pit_dev_ops = {
 680         .read     = pit_ioport_read,
 681         .write    = pit_ioport_write,
 682 };
 683
 684 static const struct kvm_io_device_ops speaker_dev_ops = {
 685         .read     = speaker_ioport_read,
 686         .write    = speaker_ioport_write,
 687 };
 688
 689 /* Caller must hold slots_lock */
 690 struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
 691 {
 692         struct kvm_pit *pit;
 693         struct kvm_kpit_state *pit_state;
 694         int ret;
 695
 696         pit = kzalloc(sizeof(struct kvm_pit), GFP_KERNEL);
 697         if (!pit)
 698                 return NULL;
 699
 700         pit->irq_source_id = kvm_request_irq_source_id(kvm);
 701         if (pit->irq_source_id < 0) {
 702                 kfree(pit);
 703                 return NULL;
 704         }
 705
 706         mutex_init(&pit->pit_state.lock);
 707         mutex_lock(&pit->pit_state.lock);
 708         spin_lock_init(&pit->pit_state.inject_lock);
 709
 710         pit->wq = create_singlethread_workqueue("kvm-pit-wq");
 711         if (!pit->wq) {
 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_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->pit_timer.timer,
 725                      CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 726         pit_state->irq_ack_notifier.gsi = 0;
 727         pit_state->irq_ack_notifier.irq_acked = kvm_pit_ack_irq;
 728         kvm_register_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
 729         pit_state->pit_timer.reinject = true;
 730         mutex_unlock(&pit->pit_state.lock);
 731
 732         kvm_pit_reset(pit);
 733
 734         pit->mask_notifier.func = pit_mask_notifer;
 735         kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
 736
 737         kvm_iodevice_init(&pit->dev, &pit_dev_ops);
 738         ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, KVM_PIT_BASE_ADDRESS,
 739                                       KVM_PIT_MEM_LENGTH, &pit->dev);
 740         if (ret < 0)
 741                 goto fail;
 742
 743         if (flags & KVM_PIT_SPEAKER_DUMMY) {
 744                 kvm_iodevice_init(&pit->speaker_dev, &speaker_dev_ops);
 745                 ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS,
 746                                               KVM_SPEAKER_BASE_ADDRESS, 4,
 747                                               &pit->speaker_dev);
 748                 if (ret < 0)
 749                         goto fail_unregister;
 750         }
 751
 752         return pit;
 753
 754 fail_unregister:
 755         kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev);
 756
 757 fail:
 758         kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
 759         kvm_unregister_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
 760         kvm_free_irq_source_id(kvm, pit->irq_source_id);
 761         destroy_workqueue(pit->wq);
 762         kfree(pit);
 763         return NULL;
 764 }
 765
 766 void kvm_free_pit(struct kvm *kvm)
 767 {
 768         struct hrtimer *timer;
 769
 770         if (kvm->arch.vpit) {
 771                 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &kvm->arch.vpit->dev);
 772                 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS,
 773                                               &kvm->arch.vpit->speaker_dev);
 774                 kvm_unregister_irq_mask_notifier(kvm, 0,
 775                                                &kvm->arch.vpit->mask_notifier);
 776                 kvm_unregister_irq_ack_notifier(kvm,
 777                                 &kvm->arch.vpit->pit_state.irq_ack_notifier);
 778                 mutex_lock(&kvm->arch.vpit->pit_state.lock);
 779                 timer = &kvm->arch.vpit->pit_state.pit_timer.timer;
 780                 hrtimer_cancel(timer);
 781                 cancel_work_sync(&kvm->arch.vpit->expired);
 782                 kvm_free_irq_source_id(kvm, kvm->arch.vpit->irq_source_id);
 783                 mutex_unlock(&kvm->arch.vpit->pit_state.lock);
 784                 destroy_workqueue(kvm->arch.vpit->wq);
 785                 kfree(kvm->arch.vpit);
 786         }
 787 }