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         mutex_lock(&pit->pit_state.lock);
 268         if (hrtimer_cancel(timer))
 269                 hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 270         mutex_unlock(&pit->pit_state.lock);
 271 }
 272
 273 static void destroy_pit_timer(struct kvm_pit *pit)
 274 {
 275         hrtimer_cancel(&pit->pit_state.pit_timer.timer);
 276         cancel_work_sync(&pit->expired);
 277 }
 278
 279 static bool kpit_is_periodic(struct kvm_timer *ktimer)
 280 {
 281         struct kvm_kpit_state *ps = container_of(ktimer, struct kvm_kpit_state,
 282                                                  pit_timer);
 283         return ps->is_periodic;
 284 }
 285
 286 static struct kvm_timer_ops kpit_ops = {
 287         .is_periodic = kpit_is_periodic,
 288 };
 289
 290 static void pit_do_work(struct work_struct *work)
 291 {
 292         struct kvm_pit *pit = container_of(work, struct kvm_pit, expired);
 293         struct kvm *kvm = pit->kvm;
 294         struct kvm_vcpu *vcpu;
 295         int i;
 296         struct kvm_kpit_state *ps = &pit->pit_state;
 297         int inject = 0;
 298
 299         /* Try to inject pending interrupts when
 300          * last one has been acked.
 301          */
 302         spin_lock(&ps->inject_lock);
 303         if (ps->irq_ack) {
 304                 ps->irq_ack = 0;
 305                 inject = 1;
 306         }
 307         spin_unlock(&ps->inject_lock);
 308         if (inject) {
 309                 kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 1);
 310                 kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 0);
 311
 312                 /*
 313                  * Provides NMI watchdog support via Virtual Wire mode.
 314                  * The route is: PIT -> PIC -> LVT0 in NMI mode.
 315                  *
 316                  * Note: Our Virtual Wire implementation is simplified, only
 317                  * propagating PIT interrupts to all VCPUs when they have set
 318                  * LVT0 to NMI delivery. Other PIC interrupts are just sent to
 319                  * VCPU0, and only if its LVT0 is in EXTINT mode.
 320                  */
 321                 if (atomic_read(&kvm->arch.vapics_in_nmi_mode) > 0)
 322                         kvm_for_each_vcpu(i, vcpu, kvm)
 323                                 kvm_apic_nmi_wd_deliver(vcpu);
 324         }
 325 }
 326
 327 static enum hrtimer_restart pit_timer_fn(struct hrtimer *data)
 328 {
 329         struct kvm_timer *ktimer = container_of(data, struct kvm_timer, timer);
 330         struct kvm_pit *pt = ktimer->kvm->arch.vpit;
 331
 332         if (ktimer->reinject || !atomic_read(&ktimer->pending)) {
 333                 atomic_inc(&ktimer->pending);
 334                 queue_work(pt->wq, &pt->expired);
 335         }
 336
 337         if (ktimer->t_ops->is_periodic(ktimer)) {
 338                 hrtimer_add_expires_ns(&ktimer->timer, ktimer->period);
 339                 return HRTIMER_RESTART;
 340         } else
 341                 return HRTIMER_NORESTART;
 342 }
 343
 344 static void create_pit_timer(struct kvm *kvm, u32 val, int is_period)
 345 {
 346         struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
 347         struct kvm_timer *pt = &ps->pit_timer;
 348         s64 interval;
 349
 350         if (!irqchip_in_kernel(kvm))
 351                 return;
 352
 353         interval = muldiv64(val, NSEC_PER_SEC, KVM_PIT_FREQ);
 354
 355         pr_debug("create pit timer, interval is %llu nsec\n", interval);
 356
 357         /* TODO The new value only affected after the retriggered */
 358         hrtimer_cancel(&pt->timer);
 359         cancel_work_sync(&ps->pit->expired);
 360         pt->period = interval;
 361         ps->is_periodic = is_period;
 362
 363         pt->timer.function = pit_timer_fn;
 364         pt->t_ops = &kpit_ops;
 365         pt->kvm = ps->pit->kvm;
 366
 367         atomic_set(&pt->pending, 0);
 368         ps->irq_ack = 1;
 369
 370         /*
 371          * Do not allow the guest to program periodic timers with small
 372          * interval, since the hrtimers are not throttled by the host
 373          * scheduler.
 374          */
 375         if (ps->is_periodic) {
 376                 s64 min_period = min_timer_period_us * 1000LL;
 377
 378                 if (pt->period < min_period) {
 379                         pr_info_ratelimited(
 380                             "kvm: requested %lld ns "
 381                             "i8254 timer period limited to %lld ns\n",
 382                             pt->period, min_period);
 383                         pt->period = min_period;
 384                 }
 385         }
 386
 387         hrtimer_start(&pt->timer, ktime_add_ns(ktime_get(), interval),
 388                       HRTIMER_MODE_ABS);
 389 }
 390
 391 static void pit_load_count(struct kvm *kvm, int channel, u32 val)
 392 {
 393         struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
 394
 395         WARN_ON(!mutex_is_locked(&ps->lock));
 396
 397         pr_debug("load_count val is %d, channel is %d\n", val, channel);
 398
 399         /*
 400          * The largest possible initial count is 0; this is equivalent
 401          * to 216 for binary counting and 104 for BCD counting.
 402          */
 403         if (val == 0)
 404                 val = 0x10000;
 405
 406         ps->channels[channel].count = val;
 407
 408         if (channel != 0) {
 409                 ps->channels[channel].count_load_time = ktime_get();
 410                 return;
 411         }
 412
 413         /* Two types of timer
 414          * mode 1 is one shot, mode 2 is period, otherwise del timer */
 415         switch (ps->channels[0].mode) {
 416         case 0:
 417         case 1:
 418         /* FIXME: enhance mode 4 precision */
 419         case 4:
 420                 if (!(ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)) {
 421                         create_pit_timer(kvm, val, 0);
 422                 }
 423                 break;
 424         case 2:
 425         case 3:
 426                 if (!(ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)){
 427                         create_pit_timer(kvm, val, 1);
 428                 }
 429                 break;
 430         default:
 431                 destroy_pit_timer(kvm->arch.vpit);
 432         }
 433 }
 434
 435 void kvm_pit_load_count(struct kvm *kvm, int channel, u32 val, int hpet_legacy_start)
 436 {
 437         u8 saved_mode;
 438         if (hpet_legacy_start) {
 439                 /* save existing mode for later reenablement */
 440                 saved_mode = kvm->arch.vpit->pit_state.channels[0].mode;
 441                 kvm->arch.vpit->pit_state.channels[0].mode = 0xff; /* disable timer */
 442                 pit_load_count(kvm, channel, val);
 443                 kvm->arch.vpit->pit_state.channels[0].mode = saved_mode;
 444         } else {
 445                 pit_load_count(kvm, channel, val);
 446         }
 447 }
 448
 449 static inline struct kvm_pit *dev_to_pit(struct kvm_io_device *dev)
 450 {
 451         return container_of(dev, struct kvm_pit, dev);
 452 }
 453
 454 static inline struct kvm_pit *speaker_to_pit(struct kvm_io_device *dev)
 455 {
 456         return container_of(dev, struct kvm_pit, speaker_dev);
 457 }
 458
 459 static inline int pit_in_range(gpa_t addr)
 460 {
 461         return ((addr >= KVM_PIT_BASE_ADDRESS) &&
 462                 (addr < KVM_PIT_BASE_ADDRESS + KVM_PIT_MEM_LENGTH));
 463 }
 464
 465 static int pit_ioport_write(struct kvm_io_device *this,
 466                             gpa_t addr, int len, const void *data)
 467 {
 468         struct kvm_pit *pit = dev_to_pit(this);
 469         struct kvm_kpit_state *pit_state = &pit->pit_state;
 470         struct kvm *kvm = pit->kvm;
 471         int channel, access;
 472         struct kvm_kpit_channel_state *s;
 473         u32 val = *(u32 *) data;
 474         if (!pit_in_range(addr))
 475                 return -EOPNOTSUPP;
 476
 477         val  &= 0xff;
 478         addr &= KVM_PIT_CHANNEL_MASK;
 479
 480         mutex_lock(&pit_state->lock);
 481
 482         if (val != 0)
 483                 pr_debug("write addr is 0x%x, len is %d, val is 0x%x\n",
 484                          (unsigned int)addr, len, val);
 485
 486         if (addr == 3) {
 487                 channel = val >> 6;
 488                 if (channel == 3) {
 489                         /* Read-Back Command. */
 490                         for (channel = 0; channel < 3; channel++) {
 491                                 s = &pit_state->channels[channel];
 492                                 if (val & (2 << channel)) {
 493                                         if (!(val & 0x20))
 494                                                 pit_latch_count(kvm, channel);
 495                                         if (!(val & 0x10))
 496                                                 pit_latch_status(kvm, channel);
 497                                 }
 498                         }
 499                 } else {
 500                         /* Select Counter <channel>. */
 501                         s = &pit_state->channels[channel];
 502                         access = (val >> 4) & KVM_PIT_CHANNEL_MASK;
 503                         if (access == 0) {
 504                                 pit_latch_count(kvm, channel);
 505                         } else {
 506                                 s->rw_mode = access;
 507                                 s->read_state = access;
 508                                 s->write_state = access;
 509                                 s->mode = (val >> 1) & 7;
 510                                 if (s->mode > 5)
 511                                         s->mode -= 4;
 512                                 s->bcd = val & 1;
 513                         }
 514                 }
 515         } else {
 516                 /* Write Count. */
 517                 s = &pit_state->channels[addr];
 518                 switch (s->write_state) {
 519                 default:
 520                 case RW_STATE_LSB:
 521                         pit_load_count(kvm, addr, val);
 522                         break;
 523                 case RW_STATE_MSB:
 524                         pit_load_count(kvm, addr, val << 8);
 525                         break;
 526                 case RW_STATE_WORD0:
 527                         s->write_latch = val;
 528                         s->write_state = RW_STATE_WORD1;
 529                         break;
 530                 case RW_STATE_WORD1:
 531                         pit_load_count(kvm, addr, s->write_latch | (val << 8));
 532                         s->write_state = RW_STATE_WORD0;
 533                         break;
 534                 }
 535         }
 536
 537         mutex_unlock(&pit_state->lock);
 538         return 0;
 539 }
 540
 541 static int pit_ioport_read(struct kvm_io_device *this,
 542                            gpa_t addr, int len, void *data)
 543 {
 544         struct kvm_pit *pit = dev_to_pit(this);
 545         struct kvm_kpit_state *pit_state = &pit->pit_state;
 546         struct kvm *kvm = pit->kvm;
 547         int ret, count;
 548         struct kvm_kpit_channel_state *s;
 549         if (!pit_in_range(addr))
 550                 return -EOPNOTSUPP;
 551
 552         addr &= KVM_PIT_CHANNEL_MASK;
 553         if (addr == 3)
 554                 return 0;
 555
 556         s = &pit_state->channels[addr];
 557
 558         mutex_lock(&pit_state->lock);
 559
 560         if (s->status_latched) {
 561                 s->status_latched = 0;
 562                 ret = s->status;
 563         } else if (s->count_latched) {
 564                 switch (s->count_latched) {
 565                 default:
 566                 case RW_STATE_LSB:
 567                         ret = s->latched_count & 0xff;
 568                         s->count_latched = 0;
 569                         break;
 570                 case RW_STATE_MSB:
 571                         ret = s->latched_count >> 8;
 572                         s->count_latched = 0;
 573                         break;
 574                 case RW_STATE_WORD0:
 575                         ret = s->latched_count & 0xff;
 576                         s->count_latched = RW_STATE_MSB;
 577                         break;
 578                 }
 579         } else {
 580                 switch (s->read_state) {
 581                 default:
 582                 case RW_STATE_LSB:
 583                         count = pit_get_count(kvm, addr);
 584                         ret = count & 0xff;
 585                         break;
 586                 case RW_STATE_MSB:
 587                         count = pit_get_count(kvm, addr);
 588                         ret = (count >> 8) & 0xff;
 589                         break;
 590                 case RW_STATE_WORD0:
 591                         count = pit_get_count(kvm, addr);
 592                         ret = count & 0xff;
 593                         s->read_state = RW_STATE_WORD1;
 594                         break;
 595                 case RW_STATE_WORD1:
 596                         count = pit_get_count(kvm, addr);
 597                         ret = (count >> 8) & 0xff;
 598                         s->read_state = RW_STATE_WORD0;
 599                         break;
 600                 }
 601         }
 602
 603         if (len > sizeof(ret))
 604                 len = sizeof(ret);
 605         memcpy(data, (char *)&ret, len);
 606
 607         mutex_unlock(&pit_state->lock);
 608         return 0;
 609 }
 610
 611 static int speaker_ioport_write(struct kvm_io_device *this,
 612                                 gpa_t addr, int len, const void *data)
 613 {
 614         struct kvm_pit *pit = speaker_to_pit(this);
 615         struct kvm_kpit_state *pit_state = &pit->pit_state;
 616         struct kvm *kvm = pit->kvm;
 617         u32 val = *(u32 *) data;
 618         if (addr != KVM_SPEAKER_BASE_ADDRESS)
 619                 return -EOPNOTSUPP;
 620
 621         mutex_lock(&pit_state->lock);
 622         pit_state->speaker_data_on = (val >> 1) & 1;
 623         pit_set_gate(kvm, 2, val & 1);
 624         mutex_unlock(&pit_state->lock);
 625         return 0;
 626 }
 627
 628 static int speaker_ioport_read(struct kvm_io_device *this,
 629                                gpa_t addr, int len, void *data)
 630 {
 631         struct kvm_pit *pit = speaker_to_pit(this);
 632         struct kvm_kpit_state *pit_state = &pit->pit_state;
 633         struct kvm *kvm = pit->kvm;
 634         unsigned int refresh_clock;
 635         int ret;
 636         if (addr != KVM_SPEAKER_BASE_ADDRESS)
 637                 return -EOPNOTSUPP;
 638
 639         /* Refresh clock toggles at about 15us. We approximate as 2^14ns. */
 640         refresh_clock = ((unsigned int)ktime_to_ns(ktime_get()) >> 14) & 1;
 641
 642         mutex_lock(&pit_state->lock);
 643         ret = ((pit_state->speaker_data_on << 1) | pit_get_gate(kvm, 2) |
 644                 (pit_get_out(kvm, 2) << 5) | (refresh_clock << 4));
 645         if (len > sizeof(ret))
 646                 len = sizeof(ret);
 647         memcpy(data, (char *)&ret, len);
 648         mutex_unlock(&pit_state->lock);
 649         return 0;
 650 }
 651
 652 void kvm_pit_reset(struct kvm_pit *pit)
 653 {
 654         int i;
 655         struct kvm_kpit_channel_state *c;
 656
 657         mutex_lock(&pit->pit_state.lock);
 658         pit->pit_state.flags = 0;
 659         for (i = 0; i < 3; i++) {
 660                 c = &pit->pit_state.channels[i];
 661                 c->mode = 0xff;
 662                 c->gate = (i != 2);
 663                 pit_load_count(pit->kvm, i, 0);
 664         }
 665         mutex_unlock(&pit->pit_state.lock);
 666
 667         atomic_set(&pit->pit_state.pit_timer.pending, 0);
 668         pit->pit_state.irq_ack = 1;
 669 }
 670
 671 static void pit_mask_notifer(struct kvm_irq_mask_notifier *kimn, bool mask)
 672 {
 673         struct kvm_pit *pit = container_of(kimn, struct kvm_pit, mask_notifier);
 674
 675         if (!mask) {
 676                 atomic_set(&pit->pit_state.pit_timer.pending, 0);
 677                 pit->pit_state.irq_ack = 1;
 678         }
 679 }
 680
 681 static const struct kvm_io_device_ops pit_dev_ops = {
 682         .read     = pit_ioport_read,
 683         .write    = pit_ioport_write,
 684 };
 685
 686 static const struct kvm_io_device_ops speaker_dev_ops = {
 687         .read     = speaker_ioport_read,
 688         .write    = speaker_ioport_write,
 689 };
 690
 691 /* Caller must hold slots_lock */
 692 struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
 693 {
 694         struct kvm_pit *pit;
 695         struct kvm_kpit_state *pit_state;
 696         int ret;
 697
 698         pit = kzalloc(sizeof(struct kvm_pit), GFP_KERNEL);
 699         if (!pit)
 700                 return NULL;
 701
 702         pit->irq_source_id = kvm_request_irq_source_id(kvm);
 703         if (pit->irq_source_id < 0) {
 704                 kfree(pit);
 705                 return NULL;
 706         }
 707
 708         mutex_init(&pit->pit_state.lock);
 709         mutex_lock(&pit->pit_state.lock);
 710         spin_lock_init(&pit->pit_state.inject_lock);
 711
 712         pit->wq = create_singlethread_workqueue("kvm-pit-wq");
 713         if (!pit->wq) {
 714                 mutex_unlock(&pit->pit_state.lock);
 715                 kvm_free_irq_source_id(kvm, pit->irq_source_id);
 716                 kfree(pit);
 717                 return NULL;
 718         }
 719         INIT_WORK(&pit->expired, pit_do_work);
 720
 721         kvm->arch.vpit = pit;
 722         pit->kvm = kvm;
 723
 724         pit_state = &pit->pit_state;
 725         pit_state->pit = pit;
 726         hrtimer_init(&pit_state->pit_timer.timer,
 727                      CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 728         pit_state->irq_ack_notifier.gsi = 0;
 729         pit_state->irq_ack_notifier.irq_acked = kvm_pit_ack_irq;
 730         kvm_register_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
 731         pit_state->pit_timer.reinject = true;
 732         mutex_unlock(&pit->pit_state.lock);
 733
 734         kvm_pit_reset(pit);
 735
 736         pit->mask_notifier.func = pit_mask_notifer;
 737         kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
 738
 739         kvm_iodevice_init(&pit->dev, &pit_dev_ops);
 740         ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, KVM_PIT_BASE_ADDRESS,
 741                                       KVM_PIT_MEM_LENGTH, &pit->dev);
 742         if (ret < 0)
 743                 goto fail;
 744
 745         if (flags & KVM_PIT_SPEAKER_DUMMY) {
 746                 kvm_iodevice_init(&pit->speaker_dev, &speaker_dev_ops);
 747                 ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS,
 748                                               KVM_SPEAKER_BASE_ADDRESS, 4,
 749                                               &pit->speaker_dev);
 750                 if (ret < 0)
 751                         goto fail_unregister;
 752         }
 753
 754         return pit;
 755
 756 fail_unregister:
 757         kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev);
 758
 759 fail:
 760         kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
 761         kvm_unregister_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
 762         kvm_free_irq_source_id(kvm, pit->irq_source_id);
 763         destroy_workqueue(pit->wq);
 764         kfree(pit);
 765         return NULL;
 766 }
 767
 768 void kvm_free_pit(struct kvm *kvm)
 769 {
 770         struct hrtimer *timer;
 771
 772         if (kvm->arch.vpit) {
 773                 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &kvm->arch.vpit->dev);
 774                 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS,
 775                                               &kvm->arch.vpit->speaker_dev);
 776                 kvm_unregister_irq_mask_notifier(kvm, 0,
 777                                                &kvm->arch.vpit->mask_notifier);
 778                 kvm_unregister_irq_ack_notifier(kvm,
 779                                 &kvm->arch.vpit->pit_state.irq_ack_notifier);
 780                 mutex_lock(&kvm->arch.vpit->pit_state.lock);
 781                 timer = &kvm->arch.vpit->pit_state.pit_timer.timer;
 782                 hrtimer_cancel(timer);
 783                 cancel_work_sync(&kvm->arch.vpit->expired);
 784                 kvm_free_irq_source_id(kvm, kvm->arch.vpit->irq_source_id);
 785                 mutex_unlock(&kvm->arch.vpit->pit_state.lock);
 786                 destroy_workqueue(kvm->arch.vpit->wq);
 787                 kfree(kvm->arch.vpit);
 788         }
 789 }