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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_64(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 */
  49 static 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_64(rh, c);
  64         res.l.low = div64_64(((mod_64(rh, c) << 32) + (rl & 0xffffffff)), c);
  65         return res.ll;
  66 }
  67
  68 static 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
  94 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
 101 static 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
 131 static 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
 166 static 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
 179 static 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
 196 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         atomic_inc(&pt->pending);
 202         smp_mb__after_atomic_inc();
 203         /* FIXME: handle case where the guest is in guest mode */
 204         if (vcpu0 && waitqueue_active(&vcpu0->wq)) {
 205                 vcpu0->arch.mp_state = VCPU_MP_STATE_RUNNABLE;
 206                 wake_up_interruptible(&vcpu0->wq);
 207         }
 208
 209         pt->timer.expires = ktime_add_ns(pt->timer.expires, pt->period);
 210         pt->scheduled = ktime_to_ns(pt->timer.expires);
 211
 212         return (pt->period == 0 ? 0 : 1);
 213 }
 214
 215 static enum hrtimer_restart pit_timer_fn(struct hrtimer *data)
 216 {
 217         struct kvm_kpit_state *ps;
 218         int restart_timer = 0;
 219
 220         ps = container_of(data, struct kvm_kpit_state, pit_timer.timer);
 221
 222         restart_timer = __pit_timer_fn(ps);
 223
 224         if (restart_timer)
 225                 return HRTIMER_RESTART;
 226         else
 227                 return HRTIMER_NORESTART;
 228 }
 229
 230 static void destroy_pit_timer(struct kvm_kpit_timer *pt)
 231 {
 232         pr_debug("pit: execute del timer!\n");
 233         hrtimer_cancel(&pt->timer);
 234 }
 235
 236 static void create_pit_timer(struct kvm_kpit_timer *pt, u32 val, int is_period)
 237 {
 238         s64 interval;
 239
 240         interval = muldiv64(val, NSEC_PER_SEC, KVM_PIT_FREQ);
 241
 242         pr_debug("pit: create pit timer, interval is %llu nsec\n", interval);
 243
 244         /* TODO The new value only affected after the retriggered */
 245         hrtimer_cancel(&pt->timer);
 246         pt->period = (is_period == 0) ? 0 : interval;
 247         pt->timer.function = pit_timer_fn;
 248         atomic_set(&pt->pending, 0);
 249
 250         hrtimer_start(&pt->timer, ktime_add_ns(ktime_get(), interval),
 251                       HRTIMER_MODE_ABS);
 252 }
 253
 254 static void pit_load_count(struct kvm *kvm, int channel, u32 val)
 255 {
 256         struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
 257
 258         WARN_ON(!mutex_is_locked(&ps->lock));
 259
 260         pr_debug("pit: load_count val is %d, channel is %d\n", val, channel);
 261
 262         /*
 263          * Though spec said the state of 8254 is undefined after power-up,
 264          * seems some tricky OS like Windows XP depends on IRQ0 interrupt
 265          * when booting up.
 266          * So here setting initialize rate for it, and not a specific number
 267          */
 268         if (val == 0)
 269                 val = 0x10000;
 270
 271         ps->channels[channel].count_load_time = ktime_get();
 272         ps->channels[channel].count = val;
 273
 274         if (channel != 0)
 275                 return;
 276
 277         /* Two types of timer
 278          * mode 1 is one shot, mode 2 is period, otherwise del timer */
 279         switch (ps->channels[0].mode) {
 280         case 1:
 281                 create_pit_timer(&ps->pit_timer, val, 0);
 282                 break;
 283         case 2:
 284                 create_pit_timer(&ps->pit_timer, val, 1);
 285                 break;
 286         default:
 287                 destroy_pit_timer(&ps->pit_timer);
 288         }
 289 }
 290
 291 static void pit_ioport_write(struct kvm_io_device *this,
 292                              gpa_t addr, int len, const void *data)
 293 {
 294         struct kvm_pit *pit = (struct kvm_pit *)this->private;
 295         struct kvm_kpit_state *pit_state = &pit->pit_state;
 296         struct kvm *kvm = pit->kvm;
 297         int channel, access;
 298         struct kvm_kpit_channel_state *s;
 299         u32 val = *(u32 *) data;
 300
 301         val  &= 0xff;
 302         addr &= KVM_PIT_CHANNEL_MASK;
 303
 304         mutex_lock(&pit_state->lock);
 305
 306         if (val != 0)
 307                 pr_debug("pit: write addr is 0x%x, len is %d, val is 0x%x\n",
 308                           (unsigned int)addr, len, val);
 309
 310         if (addr == 3) {
 311                 channel = val >> 6;
 312                 if (channel == 3) {
 313                         /* Read-Back Command. */
 314                         for (channel = 0; channel < 3; channel++) {
 315                                 s = &pit_state->channels[channel];
 316                                 if (val & (2 << channel)) {
 317                                         if (!(val & 0x20))
 318                                                 pit_latch_count(kvm, channel);
 319                                         if (!(val & 0x10))
 320                                                 pit_latch_status(kvm, channel);
 321                                 }
 322                         }
 323                 } else {
 324                         /* Select Counter <channel>. */
 325                         s = &pit_state->channels[channel];
 326                         access = (val >> 4) & KVM_PIT_CHANNEL_MASK;
 327                         if (access == 0) {
 328                                 pit_latch_count(kvm, channel);
 329                         } else {
 330                                 s->rw_mode = access;
 331                                 s->read_state = access;
 332                                 s->write_state = access;
 333                                 s->mode = (val >> 1) & 7;
 334                                 if (s->mode > 5)
 335                                         s->mode -= 4;
 336                                 s->bcd = val & 1;
 337                         }
 338                 }
 339         } else {
 340                 /* Write Count. */
 341                 s = &pit_state->channels[addr];
 342                 switch (s->write_state) {
 343                 default:
 344                 case RW_STATE_LSB:
 345                         pit_load_count(kvm, addr, val);
 346                         break;
 347                 case RW_STATE_MSB:
 348                         pit_load_count(kvm, addr, val << 8);
 349                         break;
 350                 case RW_STATE_WORD0:
 351                         s->write_latch = val;
 352                         s->write_state = RW_STATE_WORD1;
 353                         break;
 354                 case RW_STATE_WORD1:
 355                         pit_load_count(kvm, addr, s->write_latch | (val << 8));
 356                         s->write_state = RW_STATE_WORD0;
 357                         break;
 358                 }
 359         }
 360
 361         mutex_unlock(&pit_state->lock);
 362 }
 363
 364 static void pit_ioport_read(struct kvm_io_device *this,
 365                             gpa_t addr, int len, void *data)
 366 {
 367         struct kvm_pit *pit = (struct kvm_pit *)this->private;
 368         struct kvm_kpit_state *pit_state = &pit->pit_state;
 369         struct kvm *kvm = pit->kvm;
 370         int ret, count;
 371         struct kvm_kpit_channel_state *s;
 372
 373         addr &= KVM_PIT_CHANNEL_MASK;
 374         s = &pit_state->channels[addr];
 375
 376         mutex_lock(&pit_state->lock);
 377
 378         if (s->status_latched) {
 379                 s->status_latched = 0;
 380                 ret = s->status;
 381         } else if (s->count_latched) {
 382                 switch (s->count_latched) {
 383                 default:
 384                 case RW_STATE_LSB:
 385                         ret = s->latched_count & 0xff;
 386                         s->count_latched = 0;
 387                         break;
 388                 case RW_STATE_MSB:
 389                         ret = s->latched_count >> 8;
 390                         s->count_latched = 0;
 391                         break;
 392                 case RW_STATE_WORD0:
 393                         ret = s->latched_count & 0xff;
 394                         s->count_latched = RW_STATE_MSB;
 395                         break;
 396                 }
 397         } else {
 398                 switch (s->read_state) {
 399                 default:
 400                 case RW_STATE_LSB:
 401                         count = pit_get_count(kvm, addr);
 402                         ret = count & 0xff;
 403                         break;
 404                 case RW_STATE_MSB:
 405                         count = pit_get_count(kvm, addr);
 406                         ret = (count >> 8) & 0xff;
 407                         break;
 408                 case RW_STATE_WORD0:
 409                         count = pit_get_count(kvm, addr);
 410                         ret = count & 0xff;
 411                         s->read_state = RW_STATE_WORD1;
 412                         break;
 413                 case RW_STATE_WORD1:
 414                         count = pit_get_count(kvm, addr);
 415                         ret = (count >> 8) & 0xff;
 416                         s->read_state = RW_STATE_WORD0;
 417                         break;
 418                 }
 419         }
 420
 421         if (len > sizeof(ret))
 422                 len = sizeof(ret);
 423         memcpy(data, (char *)&ret, len);
 424
 425         mutex_unlock(&pit_state->lock);
 426 }
 427
 428 static int pit_in_range(struct kvm_io_device *this, gpa_t addr)
 429 {
 430         return ((addr >= KVM_PIT_BASE_ADDRESS) &&
 431                 (addr < KVM_PIT_BASE_ADDRESS + KVM_PIT_MEM_LENGTH));
 432 }
 433
 434 static void speaker_ioport_write(struct kvm_io_device *this,
 435                                  gpa_t addr, int len, const void *data)
 436 {
 437         struct kvm_pit *pit = (struct kvm_pit *)this->private;
 438         struct kvm_kpit_state *pit_state = &pit->pit_state;
 439         struct kvm *kvm = pit->kvm;
 440         u32 val = *(u32 *) data;
 441
 442         mutex_lock(&pit_state->lock);
 443         pit_state->speaker_data_on = (val >> 1) & 1;
 444         pit_set_gate(kvm, 2, val & 1);
 445         mutex_unlock(&pit_state->lock);
 446 }
 447
 448 static void speaker_ioport_read(struct kvm_io_device *this,
 449                                 gpa_t addr, int len, void *data)
 450 {
 451         struct kvm_pit *pit = (struct kvm_pit *)this->private;
 452         struct kvm_kpit_state *pit_state = &pit->pit_state;
 453         struct kvm *kvm = pit->kvm;
 454         unsigned int refresh_clock;
 455         int ret;
 456
 457         /* Refresh clock toggles at about 15us. We approximate as 2^14ns. */
 458         refresh_clock = ((unsigned int)ktime_to_ns(ktime_get()) >> 14) & 1;
 459
 460         mutex_lock(&pit_state->lock);
 461         ret = ((pit_state->speaker_data_on << 1) | pit_get_gate(kvm, 2) |
 462                 (pit_get_out(kvm, 2) << 5) | (refresh_clock << 4));
 463         if (len > sizeof(ret))
 464                 len = sizeof(ret);
 465         memcpy(data, (char *)&ret, len);
 466         mutex_unlock(&pit_state->lock);
 467 }
 468
 469 static int speaker_in_range(struct kvm_io_device *this, gpa_t addr)
 470 {
 471         return (addr == KVM_SPEAKER_BASE_ADDRESS);
 472 }
 473
 474 struct kvm_pit *kvm_create_pit(struct kvm *kvm)
 475 {
 476         int i;
 477         struct kvm_pit *pit;
 478         struct kvm_kpit_state *pit_state;
 479         struct kvm_kpit_channel_state *c;
 480
 481         pit = kzalloc(sizeof(struct kvm_pit), GFP_KERNEL);
 482         if (!pit)
 483                 return NULL;
 484
 485         mutex_init(&pit->pit_state.lock);
 486         mutex_lock(&pit->pit_state.lock);
 487
 488         /* Initialize PIO device */
 489         pit->dev.read = pit_ioport_read;
 490         pit->dev.write = pit_ioport_write;
 491         pit->dev.in_range = pit_in_range;
 492         pit->dev.private = pit;
 493         kvm_io_bus_register_dev(&kvm->pio_bus, &pit->dev);
 494
 495         pit->speaker_dev.read = speaker_ioport_read;
 496         pit->speaker_dev.write = speaker_ioport_write;
 497         pit->speaker_dev.in_range = speaker_in_range;
 498         pit->speaker_dev.private = pit;
 499         kvm_io_bus_register_dev(&kvm->pio_bus, &pit->speaker_dev);
 500
 501         kvm->arch.vpit = pit;
 502         pit->kvm = kvm;
 503
 504         pit_state = &pit->pit_state;
 505         pit_state->pit = pit;
 506         hrtimer_init(&pit_state->pit_timer.timer,
 507                      CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 508         atomic_set(&pit_state->pit_timer.pending, 0);
 509         for (i = 0; i < 3; i++) {
 510                 c = &pit_state->channels[i];
 511                 c->mode = 0xff;
 512                 c->gate = (i != 2);
 513                 pit_load_count(kvm, i, 0);
 514         }
 515
 516         mutex_unlock(&pit->pit_state.lock);
 517
 518         pit->pit_state.inject_pending = 1;
 519
 520         return pit;
 521 }
 522
 523 void kvm_free_pit(struct kvm *kvm)
 524 {
 525         struct hrtimer *timer;
 526
 527         if (kvm->arch.vpit) {
 528                 mutex_lock(&kvm->arch.vpit->pit_state.lock);
 529                 timer = &kvm->arch.vpit->pit_state.pit_timer.timer;
 530                 hrtimer_cancel(timer);
 531                 mutex_unlock(&kvm->arch.vpit->pit_state.lock);
 532                 kfree(kvm->arch.vpit);
 533         }
 534 }
 535
 536 void __inject_pit_timer_intr(struct kvm *kvm)
 537 {
 538         mutex_lock(&kvm->lock);
 539         kvm_ioapic_set_irq(kvm->arch.vioapic, 0, 1);
 540         kvm_ioapic_set_irq(kvm->arch.vioapic, 0, 0);
 541         kvm_pic_set_irq(pic_irqchip(kvm), 0, 1);
 542         kvm_pic_set_irq(pic_irqchip(kvm), 0, 0);
 543         mutex_unlock(&kvm->lock);
 544 }
 545
 546 void kvm_inject_pit_timer_irqs(struct kvm_vcpu *vcpu)
 547 {
 548         struct kvm_pit *pit = vcpu->kvm->arch.vpit;
 549         struct kvm *kvm = vcpu->kvm;
 550         struct kvm_kpit_state *ps;
 551
 552         if (vcpu && pit) {
 553                 ps = &pit->pit_state;
 554
 555                 /* Try to inject pending interrupts when:
 556                  * 1. Pending exists
 557                  * 2. Last interrupt was accepted or waited for too long time*/
 558                 if (atomic_read(&ps->pit_timer.pending) &&
 559                     (ps->inject_pending ||
 560                     (jiffies - ps->last_injected_time
 561                                 >= KVM_MAX_PIT_INTR_INTERVAL))) {
 562                         ps->inject_pending = 0;
 563                         __inject_pit_timer_intr(kvm);
 564                         ps->last_injected_time = jiffies;
 565                 }
 566         }
 567 }
 568
 569 void kvm_pit_timer_intr_post(struct kvm_vcpu *vcpu, int vec)
 570 {
 571         struct kvm_arch *arch = &vcpu->kvm->arch;
 572         struct kvm_kpit_state *ps;
 573
 574         if (vcpu && arch->vpit) {
 575                 ps = &arch->vpit->pit_state;
 576                 if (atomic_read(&ps->pit_timer.pending) &&
 577                 (((arch->vpic->pics[0].imr & 1) == 0 &&
 578                   arch->vpic->pics[0].irq_base == vec) ||
 579                   (arch->vioapic->redirtbl[0].fields.vector == vec &&
 580                   arch->vioapic->redirtbl[0].fields.mask != 1))) {
 581                         ps->inject_pending = 1;
 582                         atomic_dec(&ps->pit_timer.pending);
 583                         ps->channels[0].count_load_time = ktime_get();
 584                 }
 585         }
 586 }