linux/arch/x86/kvm/i8254.c
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   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 *
   9 * Permission is hereby granted, free of charge, to any person obtaining a copy
  10 * of this software and associated documentation files (the "Software"), to deal
  11 * in the Software without restriction, including without limitation the rights
  12 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  13 * copies of the Software, and to permit persons to whom the Software is
  14 * furnished to do so, subject to the following conditions:
  15 *
  16 * The above copyright notice and this permission notice shall be included in
  17 * all copies or substantial portions of the Software.
  18 *
  19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  22 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  23 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  24 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  25 * THE SOFTWARE.
  26 *
  27 * Authors:
  28 *   Sheng Yang <sheng.yang@intel.com>
  29 *   Based on QEMU and Xen.
  30 */
  31
  32#include <linux/kvm_host.h>
  33
  34#include "irq.h"
  35#include "i8254.h"
  36
  37#ifndef CONFIG_X86_64
  38#define mod_64(x, y) ((x) - (y) * div64_u64(x, y))
  39#else
  40#define mod_64(x, y) ((x) % (y))
  41#endif
  42
  43#define RW_STATE_LSB 1
  44#define RW_STATE_MSB 2
  45#define RW_STATE_WORD0 3
  46#define RW_STATE_WORD1 4
  47
  48/* Compute with 96 bit intermediate result: (a*b)/c */
  49static u64 muldiv64(u64 a, u32 b, u32 c)
  50{
  51        union {
  52                u64 ll;
  53                struct {
  54                        u32 low, high;
  55                } l;
  56        } u, res;
  57        u64 rl, rh;
  58
  59        u.ll = a;
  60        rl = (u64)u.l.low * (u64)b;
  61        rh = (u64)u.l.high * (u64)b;
  62        rh += (rl >> 32);
  63        res.l.high = div64_u64(rh, c);
  64        res.l.low = div64_u64(((mod_64(rh, c) << 32) + (rl & 0xffffffff)), c);
  65        return res.ll;
  66}
  67
  68static void pit_set_gate(struct kvm *kvm, int channel, u32 val)
  69{
  70        struct kvm_kpit_channel_state *c =
  71                &kvm->arch.vpit->pit_state.channels[channel];
  72
  73        WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
  74
  75        switch (c->mode) {
  76        default:
  77        case 0:
  78        case 4:
  79                /* XXX: just disable/enable counting */
  80                break;
  81        case 1:
  82        case 2:
  83        case 3:
  84        case 5:
  85                /* Restart counting on rising edge. */
  86                if (c->gate < val)
  87                        c->count_load_time = ktime_get();
  88                break;
  89        }
  90
  91        c->gate = val;
  92}
  93
  94static int pit_get_gate(struct kvm *kvm, int channel)
  95{
  96        WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
  97
  98        return kvm->arch.vpit->pit_state.channels[channel].gate;
  99}
 100
 101static int pit_get_count(struct kvm *kvm, int channel)
 102{
 103        struct kvm_kpit_channel_state *c =
 104                &kvm->arch.vpit->pit_state.channels[channel];
 105        s64 d, t;
 106        int counter;
 107
 108        WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 109
 110        t = ktime_to_ns(ktime_sub(ktime_get(), c->count_load_time));
 111        d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC);
 112
 113        switch (c->mode) {
 114        case 0:
 115        case 1:
 116        case 4:
 117        case 5:
 118                counter = (c->count - d) & 0xffff;
 119                break;
 120        case 3:
 121                /* XXX: may be incorrect for odd counts */
 122                counter = c->count - (mod_64((2 * d), c->count));
 123                break;
 124        default:
 125                counter = c->count - mod_64(d, c->count);
 126                break;
 127        }
 128        return counter;
 129}
 130
 131static int pit_get_out(struct kvm *kvm, int channel)
 132{
 133        struct kvm_kpit_channel_state *c =
 134                &kvm->arch.vpit->pit_state.channels[channel];
 135        s64 d, t;
 136        int out;
 137
 138        WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 139
 140        t = ktime_to_ns(ktime_sub(ktime_get(), c->count_load_time));
 141        d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC);
 142
 143        switch (c->mode) {
 144        default:
 145        case 0:
 146                out = (d >= c->count);
 147                break;
 148        case 1:
 149                out = (d < c->count);
 150                break;
 151        case 2:
 152                out = ((mod_64(d, c->count) == 0) && (d != 0));
 153                break;
 154        case 3:
 155                out = (mod_64(d, c->count) < ((c->count + 1) >> 1));
 156                break;
 157        case 4:
 158        case 5:
 159                out = (d == c->count);
 160                break;
 161        }
 162
 163        return out;
 164}
 165
 166static void pit_latch_count(struct kvm *kvm, int channel)
 167{
 168        struct kvm_kpit_channel_state *c =
 169                &kvm->arch.vpit->pit_state.channels[channel];
 170
 171        WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 172
 173        if (!c->count_latched) {
 174                c->latched_count = pit_get_count(kvm, channel);
 175                c->count_latched = c->rw_mode;
 176        }
 177}
 178
 179static void pit_latch_status(struct kvm *kvm, int channel)
 180{
 181        struct kvm_kpit_channel_state *c =
 182                &kvm->arch.vpit->pit_state.channels[channel];
 183
 184        WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
 185
 186        if (!c->status_latched) {
 187                /* TODO: Return NULL COUNT (bit 6). */
 188                c->status = ((pit_get_out(kvm, channel) << 7) |
 189                                (c->rw_mode << 4) |
 190                                (c->mode << 1) |
 191                                c->bcd);
 192                c->status_latched = 1;
 193        }
 194}
 195
 196static int __pit_timer_fn(struct kvm_kpit_state *ps)
 197{
 198        struct kvm_vcpu *vcpu0 = ps->pit->kvm->vcpus[0];
 199        struct kvm_kpit_timer *pt = &ps->pit_timer;
 200
 201        if (!atomic_inc_and_test(&pt->pending))
 202                set_bit(KVM_REQ_PENDING_TIMER, &vcpu0->requests);
 203
 204        if (vcpu0 && waitqueue_active(&vcpu0->wq))
 205                wake_up_interruptible(&vcpu0->wq);
 206
 207        hrtimer_add_expires_ns(&pt->timer, pt->period);
 208        pt->scheduled = hrtimer_get_expires_ns(&pt->timer);
 209        if (pt->period)
 210                ps->channels[0].count_load_time = hrtimer_get_expires(&pt->timer);
 211
 212        return (pt->period == 0 ? 0 : 1);
 213}
 214
 215int pit_has_pending_timer(struct kvm_vcpu *vcpu)
 216{
 217        struct kvm_pit *pit = vcpu->kvm->arch.vpit;
 218
 219        if (pit && vcpu->vcpu_id == 0 && pit->pit_state.irq_ack)
 220                return atomic_read(&pit->pit_state.pit_timer.pending);
 221        return 0;
 222}
 223
 224static void kvm_pit_ack_irq(struct kvm_irq_ack_notifier *kian)
 225{
 226        struct kvm_kpit_state *ps = container_of(kian, struct kvm_kpit_state,
 227                                                 irq_ack_notifier);
 228        spin_lock(&ps->inject_lock);
 229        if (atomic_dec_return(&ps->pit_timer.pending) < 0)
 230                atomic_inc(&ps->pit_timer.pending);
 231        ps->irq_ack = 1;
 232        spin_unlock(&ps->inject_lock);
 233}
 234
 235static enum hrtimer_restart pit_timer_fn(struct hrtimer *data)
 236{
 237        struct kvm_kpit_state *ps;
 238        int restart_timer = 0;
 239
 240        ps = container_of(data, struct kvm_kpit_state, pit_timer.timer);
 241
 242        restart_timer = __pit_timer_fn(ps);
 243
 244        if (restart_timer)
 245                return HRTIMER_RESTART;
 246        else
 247                return HRTIMER_NORESTART;
 248}
 249
 250void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu)
 251{
 252        struct kvm_pit *pit = vcpu->kvm->arch.vpit;
 253        struct hrtimer *timer;
 254
 255        if (vcpu->vcpu_id != 0 || !pit)
 256                return;
 257
 258        timer = &pit->pit_state.pit_timer.timer;
 259        if (hrtimer_cancel(timer))
 260                hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 261}
 262
 263static void destroy_pit_timer(struct kvm_kpit_timer *pt)
 264{
 265        pr_debug("pit: execute del timer!\n");
 266        hrtimer_cancel(&pt->timer);
 267}
 268
 269static void create_pit_timer(struct kvm_kpit_state *ps, u32 val, int is_period)
 270{
 271        struct kvm_kpit_timer *pt = &ps->pit_timer;
 272        s64 interval;
 273
 274        interval = muldiv64(val, NSEC_PER_SEC, KVM_PIT_FREQ);
 275
 276        pr_debug("pit: create pit timer, interval is %llu nsec\n", interval);
 277
 278        /* TODO The new value only affected after the retriggered */
 279        hrtimer_cancel(&pt->timer);
 280        pt->period = (is_period == 0) ? 0 : interval;
 281        pt->timer.function = pit_timer_fn;
 282        atomic_set(&pt->pending, 0);
 283        ps->irq_ack = 1;
 284
 285        hrtimer_start(&pt->timer, ktime_add_ns(ktime_get(), interval),
 286                      HRTIMER_MODE_ABS);
 287}
 288
 289static void pit_load_count(struct kvm *kvm, int channel, u32 val)
 290{
 291        struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
 292
 293        WARN_ON(!mutex_is_locked(&ps->lock));
 294
 295        pr_debug("pit: load_count val is %d, channel is %d\n", val, channel);
 296
 297        /*
 298         * Though spec said the state of 8254 is undefined after power-up,
 299         * seems some tricky OS like Windows XP depends on IRQ0 interrupt
 300         * when booting up.
 301         * So here setting initialize rate for it, and not a specific number
 302         */
 303        if (val == 0)
 304                val = 0x10000;
 305
 306        ps->channels[channel].count_load_time = ktime_get();
 307        ps->channels[channel].count = val;
 308
 309        if (channel != 0)
 310                return;
 311
 312        /* Two types of timer
 313         * mode 1 is one shot, mode 2 is period, otherwise del timer */
 314        switch (ps->channels[0].mode) {
 315        case 1:
 316        /* FIXME: enhance mode 4 precision */
 317        case 4:
 318                create_pit_timer(ps, val, 0);
 319                break;
 320        case 2:
 321        case 3:
 322                create_pit_timer(ps, val, 1);
 323                break;
 324        default:
 325                destroy_pit_timer(&ps->pit_timer);
 326        }
 327}
 328
 329void kvm_pit_load_count(struct kvm *kvm, int channel, u32 val)
 330{
 331        mutex_lock(&kvm->arch.vpit->pit_state.lock);
 332        pit_load_count(kvm, channel, val);
 333        mutex_unlock(&kvm->arch.vpit->pit_state.lock);
 334}
 335
 336static void pit_ioport_write(struct kvm_io_device *this,
 337                             gpa_t addr, int len, const void *data)
 338{
 339        struct kvm_pit *pit = (struct kvm_pit *)this->private;
 340        struct kvm_kpit_state *pit_state = &pit->pit_state;
 341        struct kvm *kvm = pit->kvm;
 342        int channel, access;
 343        struct kvm_kpit_channel_state *s;
 344        u32 val = *(u32 *) data;
 345
 346        val  &= 0xff;
 347        addr &= KVM_PIT_CHANNEL_MASK;
 348
 349        mutex_lock(&pit_state->lock);
 350
 351        if (val != 0)
 352                pr_debug("pit: write addr is 0x%x, len is %d, val is 0x%x\n",
 353                          (unsigned int)addr, len, val);
 354
 355        if (addr == 3) {
 356                channel = val >> 6;
 357                if (channel == 3) {
 358                        /* Read-Back Command. */
 359                        for (channel = 0; channel < 3; channel++) {
 360                                s = &pit_state->channels[channel];
 361                                if (val & (2 << channel)) {
 362                                        if (!(val & 0x20))
 363                                                pit_latch_count(kvm, channel);
 364                                        if (!(val & 0x10))
 365                                                pit_latch_status(kvm, channel);
 366                                }
 367                        }
 368                } else {
 369                        /* Select Counter <channel>. */
 370                        s = &pit_state->channels[channel];
 371                        access = (val >> 4) & KVM_PIT_CHANNEL_MASK;
 372                        if (access == 0) {
 373                                pit_latch_count(kvm, channel);
 374                        } else {
 375                                s->rw_mode = access;
 376                                s->read_state = access;
 377                                s->write_state = access;
 378                                s->mode = (val >> 1) & 7;
 379                                if (s->mode > 5)
 380                                        s->mode -= 4;
 381                                s->bcd = val & 1;
 382                        }
 383                }
 384        } else {
 385                /* Write Count. */
 386                s = &pit_state->channels[addr];
 387                switch (s->write_state) {
 388                default:
 389                case RW_STATE_LSB:
 390                        pit_load_count(kvm, addr, val);
 391                        break;
 392                case RW_STATE_MSB:
 393                        pit_load_count(kvm, addr, val << 8);
 394                        break;
 395                case RW_STATE_WORD0:
 396                        s->write_latch = val;
 397                        s->write_state = RW_STATE_WORD1;
 398                        break;
 399                case RW_STATE_WORD1:
 400                        pit_load_count(kvm, addr, s->write_latch | (val << 8));
 401                        s->write_state = RW_STATE_WORD0;
 402                        break;
 403                }
 404        }
 405
 406        mutex_unlock(&pit_state->lock);
 407}
 408
 409static void pit_ioport_read(struct kvm_io_device *this,
 410                            gpa_t addr, int len, void *data)
 411{
 412        struct kvm_pit *pit = (struct kvm_pit *)this->private;
 413        struct kvm_kpit_state *pit_state = &pit->pit_state;
 414        struct kvm *kvm = pit->kvm;
 415        int ret, count;
 416        struct kvm_kpit_channel_state *s;
 417
 418        addr &= KVM_PIT_CHANNEL_MASK;
 419        s = &pit_state->channels[addr];
 420
 421        mutex_lock(&pit_state->lock);
 422
 423        if (s->status_latched) {
 424                s->status_latched = 0;
 425                ret = s->status;
 426        } else if (s->count_latched) {
 427                switch (s->count_latched) {
 428                default:
 429                case RW_STATE_LSB:
 430                        ret = s->latched_count & 0xff;
 431                        s->count_latched = 0;
 432                        break;
 433                case RW_STATE_MSB:
 434                        ret = s->latched_count >> 8;
 435                        s->count_latched = 0;
 436                        break;
 437                case RW_STATE_WORD0:
 438                        ret = s->latched_count & 0xff;
 439                        s->count_latched = RW_STATE_MSB;
 440                        break;
 441                }
 442        } else {
 443                switch (s->read_state) {
 444                default:
 445                case RW_STATE_LSB:
 446                        count = pit_get_count(kvm, addr);
 447                        ret = count & 0xff;
 448                        break;
 449                case RW_STATE_MSB:
 450                        count = pit_get_count(kvm, addr);
 451                        ret = (count >> 8) & 0xff;
 452                        break;
 453                case RW_STATE_WORD0:
 454                        count = pit_get_count(kvm, addr);
 455                        ret = count & 0xff;
 456                        s->read_state = RW_STATE_WORD1;
 457                        break;
 458                case RW_STATE_WORD1:
 459                        count = pit_get_count(kvm, addr);
 460                        ret = (count >> 8) & 0xff;
 461                        s->read_state = RW_STATE_WORD0;
 462                        break;
 463                }
 464        }
 465
 466        if (len > sizeof(ret))
 467                len = sizeof(ret);
 468        memcpy(data, (char *)&ret, len);
 469
 470        mutex_unlock(&pit_state->lock);
 471}
 472
 473static int pit_in_range(struct kvm_io_device *this, gpa_t addr,
 474                        int len, int is_write)
 475{
 476        return ((addr >= KVM_PIT_BASE_ADDRESS) &&
 477                (addr < KVM_PIT_BASE_ADDRESS + KVM_PIT_MEM_LENGTH));
 478}
 479
 480static void speaker_ioport_write(struct kvm_io_device *this,
 481                                 gpa_t addr, int len, const void *data)
 482{
 483        struct kvm_pit *pit = (struct kvm_pit *)this->private;
 484        struct kvm_kpit_state *pit_state = &pit->pit_state;
 485        struct kvm *kvm = pit->kvm;
 486        u32 val = *(u32 *) data;
 487
 488        mutex_lock(&pit_state->lock);
 489        pit_state->speaker_data_on = (val >> 1) & 1;
 490        pit_set_gate(kvm, 2, val & 1);
 491        mutex_unlock(&pit_state->lock);
 492}
 493
 494static void speaker_ioport_read(struct kvm_io_device *this,
 495                                gpa_t addr, int len, void *data)
 496{
 497        struct kvm_pit *pit = (struct kvm_pit *)this->private;
 498        struct kvm_kpit_state *pit_state = &pit->pit_state;
 499        struct kvm *kvm = pit->kvm;
 500        unsigned int refresh_clock;
 501        int ret;
 502
 503        /* Refresh clock toggles at about 15us. We approximate as 2^14ns. */
 504        refresh_clock = ((unsigned int)ktime_to_ns(ktime_get()) >> 14) & 1;
 505
 506        mutex_lock(&pit_state->lock);
 507        ret = ((pit_state->speaker_data_on << 1) | pit_get_gate(kvm, 2) |
 508                (pit_get_out(kvm, 2) << 5) | (refresh_clock << 4));
 509        if (len > sizeof(ret))
 510                len = sizeof(ret);
 511        memcpy(data, (char *)&ret, len);
 512        mutex_unlock(&pit_state->lock);
 513}
 514
 515static int speaker_in_range(struct kvm_io_device *this, gpa_t addr,
 516                            int len, int is_write)
 517{
 518        return (addr == KVM_SPEAKER_BASE_ADDRESS);
 519}
 520
 521void kvm_pit_reset(struct kvm_pit *pit)
 522{
 523        int i;
 524        struct kvm_kpit_channel_state *c;
 525
 526        mutex_lock(&pit->pit_state.lock);
 527        for (i = 0; i < 3; i++) {
 528                c = &pit->pit_state.channels[i];
 529                c->mode = 0xff;
 530                c->gate = (i != 2);
 531                pit_load_count(pit->kvm, i, 0);
 532        }
 533        mutex_unlock(&pit->pit_state.lock);
 534
 535        atomic_set(&pit->pit_state.pit_timer.pending, 0);
 536        pit->pit_state.irq_ack = 1;
 537}
 538
 539struct kvm_pit *kvm_create_pit(struct kvm *kvm)
 540{
 541        struct kvm_pit *pit;
 542        struct kvm_kpit_state *pit_state;
 543
 544        pit = kzalloc(sizeof(struct kvm_pit), GFP_KERNEL);
 545        if (!pit)
 546                return NULL;
 547
 548        mutex_lock(&kvm->lock);
 549        pit->irq_source_id = kvm_request_irq_source_id(kvm);
 550        mutex_unlock(&kvm->lock);
 551        if (pit->irq_source_id < 0) {
 552                kfree(pit);
 553                return NULL;
 554        }
 555
 556        mutex_init(&pit->pit_state.lock);
 557        mutex_lock(&pit->pit_state.lock);
 558        spin_lock_init(&pit->pit_state.inject_lock);
 559
 560        /* Initialize PIO device */
 561        pit->dev.read = pit_ioport_read;
 562        pit->dev.write = pit_ioport_write;
 563        pit->dev.in_range = pit_in_range;
 564        pit->dev.private = pit;
 565        kvm_io_bus_register_dev(&kvm->pio_bus, &pit->dev);
 566
 567        pit->speaker_dev.read = speaker_ioport_read;
 568        pit->speaker_dev.write = speaker_ioport_write;
 569        pit->speaker_dev.in_range = speaker_in_range;
 570        pit->speaker_dev.private = pit;
 571        kvm_io_bus_register_dev(&kvm->pio_bus, &pit->speaker_dev);
 572
 573        kvm->arch.vpit = pit;
 574        pit->kvm = kvm;
 575
 576        pit_state = &pit->pit_state;
 577        pit_state->pit = pit;
 578        hrtimer_init(&pit_state->pit_timer.timer,
 579                     CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 580        pit_state->irq_ack_notifier.gsi = 0;
 581        pit_state->irq_ack_notifier.irq_acked = kvm_pit_ack_irq;
 582        kvm_register_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
 583        mutex_unlock(&pit->pit_state.lock);
 584
 585        kvm_pit_reset(pit);
 586
 587        return pit;
 588}
 589
 590void kvm_free_pit(struct kvm *kvm)
 591{
 592        struct hrtimer *timer;
 593
 594        if (kvm->arch.vpit) {
 595                mutex_lock(&kvm->arch.vpit->pit_state.lock);
 596                timer = &kvm->arch.vpit->pit_state.pit_timer.timer;
 597                hrtimer_cancel(timer);
 598                kvm_free_irq_source_id(kvm, kvm->arch.vpit->irq_source_id);
 599                mutex_unlock(&kvm->arch.vpit->pit_state.lock);
 600                kfree(kvm->arch.vpit);
 601        }
 602}
 603
 604static void __inject_pit_timer_intr(struct kvm *kvm)
 605{
 606        mutex_lock(&kvm->lock);
 607        kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 1);
 608        kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 0);
 609        mutex_unlock(&kvm->lock);
 610}
 611
 612void kvm_inject_pit_timer_irqs(struct kvm_vcpu *vcpu)
 613{
 614        struct kvm_pit *pit = vcpu->kvm->arch.vpit;
 615        struct kvm *kvm = vcpu->kvm;
 616        struct kvm_kpit_state *ps;
 617
 618        if (vcpu && pit) {
 619                int inject = 0;
 620                ps = &pit->pit_state;
 621
 622                /* Try to inject pending interrupts when
 623                 * last one has been acked.
 624                 */
 625                spin_lock(&ps->inject_lock);
 626                if (atomic_read(&ps->pit_timer.pending) && ps->irq_ack) {
 627                        ps->irq_ack = 0;
 628                        inject = 1;
 629                }
 630                spin_unlock(&ps->inject_lock);
 631                if (inject)
 632                        __inject_pit_timer_intr(kvm);
 633        }
 634}
 635