virt/kvm/eventfd.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * kvm eventfd support - use eventfd objects to signal various KVM events
   4  *
   5  * Copyright 2009 Novell.  All Rights Reserved.
   6  * Copyright 2010 Red Hat, Inc. and/or its affiliates.
   7  *
   8  * Author:
   9  *      Gregory Haskins <ghaskins@novell.com>
  10  */
  11
  12 #include <linux/kvm_host.h>
  13 #include <linux/kvm.h>
  14 #include <linux/kvm_irqfd.h>
  15 #include <linux/workqueue.h>
  16 #include <linux/syscalls.h>
  17 #include <linux/wait.h>
  18 #include <linux/poll.h>
  19 #include <linux/file.h>
  20 #include <linux/list.h>
  21 #include <linux/eventfd.h>
  22 #include <linux/kernel.h>
  23 #include <linux/srcu.h>
  24 #include <linux/slab.h>
  25 #include <linux/seqlock.h>
  26 #include <linux/irqbypass.h>
  27 #include <trace/events/kvm.h>
  28
  29 #include <kvm/iodev.h>
  30
  31 #ifdef CONFIG_HAVE_KVM_IRQFD
  32
  33 static struct workqueue_struct *irqfd_cleanup_wq;
  34
  35 bool __attribute__((weak))
  36 kvm_arch_irqfd_allowed(struct kvm *kvm, struct kvm_irqfd *args)
  37 {
  38         return true;
  39 }
  40
  41 static void
  42 irqfd_inject(struct work_struct *work)
  43 {
  44         struct kvm_kernel_irqfd *irqfd =
  45                 container_of(work, struct kvm_kernel_irqfd, inject);
  46         struct kvm *kvm = irqfd->kvm;
  47
  48         if (!irqfd->resampler) {
  49                 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1,
  50                                 false);
  51                 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0,
  52                                 false);
  53         } else
  54                 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
  55                             irqfd->gsi, 1, false);
  56 }
  57
  58 /*
  59  * Since resampler irqfds share an IRQ source ID, we de-assert once
  60  * then notify all of the resampler irqfds using this GSI.  We can't
  61  * do multiple de-asserts or we risk racing with incoming re-asserts.
  62  */
  63 static void
  64 irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian)
  65 {
  66         struct kvm_kernel_irqfd_resampler *resampler;
  67         struct kvm *kvm;
  68         struct kvm_kernel_irqfd *irqfd;
  69         int idx;
  70
  71         resampler = container_of(kian,
  72                         struct kvm_kernel_irqfd_resampler, notifier);
  73         kvm = resampler->kvm;
  74
  75         kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
  76                     resampler->notifier.gsi, 0, false);
  77
  78         idx = srcu_read_lock(&kvm->irq_srcu);
  79
  80         list_for_each_entry_srcu(irqfd, &resampler->list, resampler_link,
  81             srcu_read_lock_held(&kvm->irq_srcu))
  82                 eventfd_signal(irqfd->resamplefd, 1);
  83
  84         srcu_read_unlock(&kvm->irq_srcu, idx);
  85 }
  86
  87 static void
  88 irqfd_resampler_shutdown(struct kvm_kernel_irqfd *irqfd)
  89 {
  90         struct kvm_kernel_irqfd_resampler *resampler = irqfd->resampler;
  91         struct kvm *kvm = resampler->kvm;
  92
  93         mutex_lock(&kvm->irqfds.resampler_lock);
  94
  95         list_del_rcu(&irqfd->resampler_link);
  96         synchronize_srcu(&kvm->irq_srcu);
  97
  98         if (list_empty(&resampler->list)) {
  99                 list_del(&resampler->link);
 100                 kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier);
 101                 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
 102                             resampler->notifier.gsi, 0, false);
 103                 kfree(resampler);
 104         }
 105
 106         mutex_unlock(&kvm->irqfds.resampler_lock);
 107 }
 108
 109 /*
 110  * Race-free decouple logic (ordering is critical)
 111  */
 112 static void
 113 irqfd_shutdown(struct work_struct *work)
 114 {
 115         struct kvm_kernel_irqfd *irqfd =
 116                 container_of(work, struct kvm_kernel_irqfd, shutdown);
 117         struct kvm *kvm = irqfd->kvm;
 118         u64 cnt;
 119
 120         /* Make sure irqfd has been initialized in assign path. */
 121         synchronize_srcu(&kvm->irq_srcu);
 122
 123         /*
 124          * Synchronize with the wait-queue and unhook ourselves to prevent
 125          * further events.
 126          */
 127         eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
 128
 129         /*
 130          * We know no new events will be scheduled at this point, so block
 131          * until all previously outstanding events have completed
 132          */
 133         flush_work(&irqfd->inject);
 134
 135         if (irqfd->resampler) {
 136                 irqfd_resampler_shutdown(irqfd);
 137                 eventfd_ctx_put(irqfd->resamplefd);
 138         }
 139
 140         /*
 141          * It is now safe to release the object's resources
 142          */
 143 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
 144         irq_bypass_unregister_consumer(&irqfd->consumer);
 145 #endif
 146         eventfd_ctx_put(irqfd->eventfd);
 147         kfree(irqfd);
 148 }
 149
 150
 151 /* assumes kvm->irqfds.lock is held */
 152 static bool
 153 irqfd_is_active(struct kvm_kernel_irqfd *irqfd)
 154 {
 155         return list_empty(&irqfd->list) ? false : true;
 156 }
 157
 158 /*
 159  * Mark the irqfd as inactive and schedule it for removal
 160  *
 161  * assumes kvm->irqfds.lock is held
 162  */
 163 static void
 164 irqfd_deactivate(struct kvm_kernel_irqfd *irqfd)
 165 {
 166         BUG_ON(!irqfd_is_active(irqfd));
 167
 168         list_del_init(&irqfd->list);
 169
 170         queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
 171 }
 172
 173 int __attribute__((weak)) kvm_arch_set_irq_inatomic(
 174                                 struct kvm_kernel_irq_routing_entry *irq,
 175                                 struct kvm *kvm, int irq_source_id,
 176                                 int level,
 177                                 bool line_status)
 178 {
 179         return -EWOULDBLOCK;
 180 }
 181
 182 /*
 183  * Called with wqh->lock held and interrupts disabled
 184  */
 185 static int
 186 irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
 187 {
 188         struct kvm_kernel_irqfd *irqfd =
 189                 container_of(wait, struct kvm_kernel_irqfd, wait);
 190         __poll_t flags = key_to_poll(key);
 191         struct kvm_kernel_irq_routing_entry irq;
 192         struct kvm *kvm = irqfd->kvm;
 193         unsigned seq;
 194         int idx;
 195         int ret = 0;
 196
 197         if (flags & EPOLLIN) {
 198                 u64 cnt;
 199                 eventfd_ctx_do_read(irqfd->eventfd, &cnt);
 200
 201                 idx = srcu_read_lock(&kvm->irq_srcu);
 202                 do {
 203                         seq = read_seqcount_begin(&irqfd->irq_entry_sc);
 204                         irq = irqfd->irq_entry;
 205                 } while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
 206                 /* An event has been signaled, inject an interrupt */
 207                 if (kvm_arch_set_irq_inatomic(&irq, kvm,
 208                                               KVM_USERSPACE_IRQ_SOURCE_ID, 1,
 209                                               false) == -EWOULDBLOCK)
 210                         schedule_work(&irqfd->inject);
 211                 srcu_read_unlock(&kvm->irq_srcu, idx);
 212                 ret = 1;
 213         }
 214
 215         if (flags & EPOLLHUP) {
 216                 /* The eventfd is closing, detach from KVM */
 217                 unsigned long iflags;
 218
 219                 spin_lock_irqsave(&kvm->irqfds.lock, iflags);
 220
 221                 /*
 222                  * We must check if someone deactivated the irqfd before
 223                  * we could acquire the irqfds.lock since the item is
 224                  * deactivated from the KVM side before it is unhooked from
 225                  * the wait-queue.  If it is already deactivated, we can
 226                  * simply return knowing the other side will cleanup for us.
 227                  * We cannot race against the irqfd going away since the
 228                  * other side is required to acquire wqh->lock, which we hold
 229                  */
 230                 if (irqfd_is_active(irqfd))
 231                         irqfd_deactivate(irqfd);
 232
 233                 spin_unlock_irqrestore(&kvm->irqfds.lock, iflags);
 234         }
 235
 236         return ret;
 237 }
 238
 239 static void
 240 irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
 241                         poll_table *pt)
 242 {
 243         struct kvm_kernel_irqfd *irqfd =
 244                 container_of(pt, struct kvm_kernel_irqfd, pt);
 245         add_wait_queue_priority(wqh, &irqfd->wait);
 246 }
 247
 248 /* Must be called under irqfds.lock */
 249 static void irqfd_update(struct kvm *kvm, struct kvm_kernel_irqfd *irqfd)
 250 {
 251         struct kvm_kernel_irq_routing_entry *e;
 252         struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
 253         int n_entries;
 254
 255         n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);
 256
 257         write_seqcount_begin(&irqfd->irq_entry_sc);
 258
 259         e = entries;
 260         if (n_entries == 1)
 261                 irqfd->irq_entry = *e;
 262         else
 263                 irqfd->irq_entry.type = 0;
 264
 265         write_seqcount_end(&irqfd->irq_entry_sc);
 266 }
 267
 268 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
 269 void __attribute__((weak)) kvm_arch_irq_bypass_stop(
 270                                 struct irq_bypass_consumer *cons)
 271 {
 272 }
 273
 274 void __attribute__((weak)) kvm_arch_irq_bypass_start(
 275                                 struct irq_bypass_consumer *cons)
 276 {
 277 }
 278
 279 int  __attribute__((weak)) kvm_arch_update_irqfd_routing(
 280                                 struct kvm *kvm, unsigned int host_irq,
 281                                 uint32_t guest_irq, bool set)
 282 {
 283         return 0;
 284 }
 285
 286 bool __attribute__((weak)) kvm_arch_irqfd_route_changed(
 287                                 struct kvm_kernel_irq_routing_entry *old,
 288                                 struct kvm_kernel_irq_routing_entry *new)
 289 {
 290         return true;
 291 }
 292 #endif
 293
 294 static int
 295 kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
 296 {
 297         struct kvm_kernel_irqfd *irqfd, *tmp;
 298         struct fd f;
 299         struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
 300         int ret;
 301         __poll_t events;
 302         int idx;
 303
 304         if (!kvm_arch_intc_initialized(kvm))
 305                 return -EAGAIN;
 306
 307         if (!kvm_arch_irqfd_allowed(kvm, args))
 308                 return -EINVAL;
 309
 310         irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL_ACCOUNT);
 311         if (!irqfd)
 312                 return -ENOMEM;
 313
 314         irqfd->kvm = kvm;
 315         irqfd->gsi = args->gsi;
 316         INIT_LIST_HEAD(&irqfd->list);
 317         INIT_WORK(&irqfd->inject, irqfd_inject);
 318         INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
 319         seqcount_spinlock_init(&irqfd->irq_entry_sc, &kvm->irqfds.lock);
 320
 321         f = fdget(args->fd);
 322         if (!f.file) {
 323                 ret = -EBADF;
 324                 goto out;
 325         }
 326
 327         eventfd = eventfd_ctx_fileget(f.file);
 328         if (IS_ERR(eventfd)) {
 329                 ret = PTR_ERR(eventfd);
 330                 goto fail;
 331         }
 332
 333         irqfd->eventfd = eventfd;
 334
 335         if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) {
 336                 struct kvm_kernel_irqfd_resampler *resampler;
 337
 338                 resamplefd = eventfd_ctx_fdget(args->resamplefd);
 339                 if (IS_ERR(resamplefd)) {
 340                         ret = PTR_ERR(resamplefd);
 341                         goto fail;
 342                 }
 343
 344                 irqfd->resamplefd = resamplefd;
 345                 INIT_LIST_HEAD(&irqfd->resampler_link);
 346
 347                 mutex_lock(&kvm->irqfds.resampler_lock);
 348
 349                 list_for_each_entry(resampler,
 350                                     &kvm->irqfds.resampler_list, link) {
 351                         if (resampler->notifier.gsi == irqfd->gsi) {
 352                                 irqfd->resampler = resampler;
 353                                 break;
 354                         }
 355                 }
 356
 357                 if (!irqfd->resampler) {
 358                         resampler = kzalloc(sizeof(*resampler),
 359                                             GFP_KERNEL_ACCOUNT);
 360                         if (!resampler) {
 361                                 ret = -ENOMEM;
 362                                 mutex_unlock(&kvm->irqfds.resampler_lock);
 363                                 goto fail;
 364                         }
 365
 366                         resampler->kvm = kvm;
 367                         INIT_LIST_HEAD(&resampler->list);
 368                         resampler->notifier.gsi = irqfd->gsi;
 369                         resampler->notifier.irq_acked = irqfd_resampler_ack;
 370                         INIT_LIST_HEAD(&resampler->link);
 371
 372                         list_add(&resampler->link, &kvm->irqfds.resampler_list);
 373                         kvm_register_irq_ack_notifier(kvm,
 374                                                       &resampler->notifier);
 375                         irqfd->resampler = resampler;
 376                 }
 377
 378                 list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list);
 379                 synchronize_srcu(&kvm->irq_srcu);
 380
 381                 mutex_unlock(&kvm->irqfds.resampler_lock);
 382         }
 383
 384         /*
 385          * Install our own custom wake-up handling so we are notified via
 386          * a callback whenever someone signals the underlying eventfd
 387          */
 388         init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
 389         init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
 390
 391         spin_lock_irq(&kvm->irqfds.lock);
 392
 393         ret = 0;
 394         list_for_each_entry(tmp, &kvm->irqfds.items, list) {
 395                 if (irqfd->eventfd != tmp->eventfd)
 396                         continue;
 397                 /* This fd is used for another irq already. */
 398                 ret = -EBUSY;
 399                 spin_unlock_irq(&kvm->irqfds.lock);
 400                 goto fail;
 401         }
 402
 403         idx = srcu_read_lock(&kvm->irq_srcu);
 404         irqfd_update(kvm, irqfd);
 405
 406         list_add_tail(&irqfd->list, &kvm->irqfds.items);
 407
 408         spin_unlock_irq(&kvm->irqfds.lock);
 409
 410         /*
 411          * Check if there was an event already pending on the eventfd
 412          * before we registered, and trigger it as if we didn't miss it.
 413          */
 414         events = vfs_poll(f.file, &irqfd->pt);
 415
 416         if (events & EPOLLIN)
 417                 schedule_work(&irqfd->inject);
 418
 419 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
 420         if (kvm_arch_has_irq_bypass()) {
 421                 irqfd->consumer.token = (void *)irqfd->eventfd;
 422                 irqfd->consumer.add_producer = kvm_arch_irq_bypass_add_producer;
 423                 irqfd->consumer.del_producer = kvm_arch_irq_bypass_del_producer;
 424                 irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
 425                 irqfd->consumer.start = kvm_arch_irq_bypass_start;
 426                 ret = irq_bypass_register_consumer(&irqfd->consumer);
 427                 if (ret)
 428                         pr_info("irq bypass consumer (token %p) registration fails: %d\n",
 429                                 irqfd->consumer.token, ret);
 430         }
 431 #endif
 432
 433         srcu_read_unlock(&kvm->irq_srcu, idx);
 434
 435         /*
 436          * do not drop the file until the irqfd is fully initialized, otherwise
 437          * we might race against the EPOLLHUP
 438          */
 439         fdput(f);
 440         return 0;
 441
 442 fail:
 443         if (irqfd->resampler)
 444                 irqfd_resampler_shutdown(irqfd);
 445
 446         if (resamplefd && !IS_ERR(resamplefd))
 447                 eventfd_ctx_put(resamplefd);
 448
 449         if (eventfd && !IS_ERR(eventfd))
 450                 eventfd_ctx_put(eventfd);
 451
 452         fdput(f);
 453
 454 out:
 455         kfree(irqfd);
 456         return ret;
 457 }
 458
 459 bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin)
 460 {
 461         struct kvm_irq_ack_notifier *kian;
 462         int gsi, idx;
 463
 464         idx = srcu_read_lock(&kvm->irq_srcu);
 465         gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
 466         if (gsi != -1)
 467                 hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list,
 468                                           link, srcu_read_lock_held(&kvm->irq_srcu))
 469                         if (kian->gsi == gsi) {
 470                                 srcu_read_unlock(&kvm->irq_srcu, idx);
 471                                 return true;
 472                         }
 473
 474         srcu_read_unlock(&kvm->irq_srcu, idx);
 475
 476         return false;
 477 }
 478 EXPORT_SYMBOL_GPL(kvm_irq_has_notifier);
 479
 480 void kvm_notify_acked_gsi(struct kvm *kvm, int gsi)
 481 {
 482         struct kvm_irq_ack_notifier *kian;
 483
 484         hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list,
 485                                   link, srcu_read_lock_held(&kvm->irq_srcu))
 486                 if (kian->gsi == gsi)
 487                         kian->irq_acked(kian);
 488 }
 489
 490 void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
 491 {
 492         int gsi, idx;
 493
 494         trace_kvm_ack_irq(irqchip, pin);
 495
 496         idx = srcu_read_lock(&kvm->irq_srcu);
 497         gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
 498         if (gsi != -1)
 499                 kvm_notify_acked_gsi(kvm, gsi);
 500         srcu_read_unlock(&kvm->irq_srcu, idx);
 501 }
 502
 503 void kvm_register_irq_ack_notifier(struct kvm *kvm,
 504                                    struct kvm_irq_ack_notifier *kian)
 505 {
 506         mutex_lock(&kvm->irq_lock);
 507         hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list);
 508         mutex_unlock(&kvm->irq_lock);
 509         kvm_arch_post_irq_ack_notifier_list_update(kvm);
 510 }
 511
 512 void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
 513                                     struct kvm_irq_ack_notifier *kian)
 514 {
 515         mutex_lock(&kvm->irq_lock);
 516         hlist_del_init_rcu(&kian->link);
 517         mutex_unlock(&kvm->irq_lock);
 518         synchronize_srcu(&kvm->irq_srcu);
 519         kvm_arch_post_irq_ack_notifier_list_update(kvm);
 520 }
 521 #endif
 522
 523 void
 524 kvm_eventfd_init(struct kvm *kvm)
 525 {
 526 #ifdef CONFIG_HAVE_KVM_IRQFD
 527         spin_lock_init(&kvm->irqfds.lock);
 528         INIT_LIST_HEAD(&kvm->irqfds.items);
 529         INIT_LIST_HEAD(&kvm->irqfds.resampler_list);
 530         mutex_init(&kvm->irqfds.resampler_lock);
 531 #endif
 532         INIT_LIST_HEAD(&kvm->ioeventfds);
 533 }
 534
 535 #ifdef CONFIG_HAVE_KVM_IRQFD
 536 /*
 537  * shutdown any irqfd's that match fd+gsi
 538  */
 539 static int
 540 kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
 541 {
 542         struct kvm_kernel_irqfd *irqfd, *tmp;
 543         struct eventfd_ctx *eventfd;
 544
 545         eventfd = eventfd_ctx_fdget(args->fd);
 546         if (IS_ERR(eventfd))
 547                 return PTR_ERR(eventfd);
 548
 549         spin_lock_irq(&kvm->irqfds.lock);
 550
 551         list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
 552                 if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) {
 553                         /*
 554                          * This clearing of irq_entry.type is needed for when
 555                          * another thread calls kvm_irq_routing_update before
 556                          * we flush workqueue below (we synchronize with
 557                          * kvm_irq_routing_update using irqfds.lock).
 558                          */
 559                         write_seqcount_begin(&irqfd->irq_entry_sc);
 560                         irqfd->irq_entry.type = 0;
 561                         write_seqcount_end(&irqfd->irq_entry_sc);
 562                         irqfd_deactivate(irqfd);
 563                 }
 564         }
 565
 566         spin_unlock_irq(&kvm->irqfds.lock);
 567         eventfd_ctx_put(eventfd);
 568
 569         /*
 570          * Block until we know all outstanding shutdown jobs have completed
 571          * so that we guarantee there will not be any more interrupts on this
 572          * gsi once this deassign function returns.
 573          */
 574         flush_workqueue(irqfd_cleanup_wq);
 575
 576         return 0;
 577 }
 578
 579 int
 580 kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
 581 {
 582         if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE))
 583                 return -EINVAL;
 584
 585         if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
 586                 return kvm_irqfd_deassign(kvm, args);
 587
 588         return kvm_irqfd_assign(kvm, args);
 589 }
 590
 591 /*
 592  * This function is called as the kvm VM fd is being released. Shutdown all
 593  * irqfds that still remain open
 594  */
 595 void
 596 kvm_irqfd_release(struct kvm *kvm)
 597 {
 598         struct kvm_kernel_irqfd *irqfd, *tmp;
 599
 600         spin_lock_irq(&kvm->irqfds.lock);
 601
 602         list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
 603                 irqfd_deactivate(irqfd);
 604
 605         spin_unlock_irq(&kvm->irqfds.lock);
 606
 607         /*
 608          * Block until we know all outstanding shutdown jobs have completed
 609          * since we do not take a kvm* reference.
 610          */
 611         flush_workqueue(irqfd_cleanup_wq);
 612
 613 }
 614
 615 /*
 616  * Take note of a change in irq routing.
 617  * Caller must invoke synchronize_srcu(&kvm->irq_srcu) afterwards.
 618  */
 619 void kvm_irq_routing_update(struct kvm *kvm)
 620 {
 621         struct kvm_kernel_irqfd *irqfd;
 622
 623         spin_lock_irq(&kvm->irqfds.lock);
 624
 625         list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
 626 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
 627                 /* Under irqfds.lock, so can read irq_entry safely */
 628                 struct kvm_kernel_irq_routing_entry old = irqfd->irq_entry;
 629 #endif
 630
 631                 irqfd_update(kvm, irqfd);
 632
 633 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
 634                 if (irqfd->producer &&
 635                     kvm_arch_irqfd_route_changed(&old, &irqfd->irq_entry)) {
 636                         int ret = kvm_arch_update_irqfd_routing(
 637                                         irqfd->kvm, irqfd->producer->irq,
 638                                         irqfd->gsi, 1);
 639                         WARN_ON(ret);
 640                 }
 641 #endif
 642         }
 643
 644         spin_unlock_irq(&kvm->irqfds.lock);
 645 }
 646
 647 /*
 648  * create a host-wide workqueue for issuing deferred shutdown requests
 649  * aggregated from all vm* instances. We need our own isolated
 650  * queue to ease flushing work items when a VM exits.
 651  */
 652 int kvm_irqfd_init(void)
 653 {
 654         irqfd_cleanup_wq = alloc_workqueue("kvm-irqfd-cleanup", 0, 0);
 655         if (!irqfd_cleanup_wq)
 656                 return -ENOMEM;
 657
 658         return 0;
 659 }
 660
 661 void kvm_irqfd_exit(void)
 662 {
 663         destroy_workqueue(irqfd_cleanup_wq);
 664 }
 665 #endif
 666
 667 /*
 668  * --------------------------------------------------------------------
 669  * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
 670  *
 671  * userspace can register a PIO/MMIO address with an eventfd for receiving
 672  * notification when the memory has been touched.
 673  * --------------------------------------------------------------------
 674  */
 675
 676 struct _ioeventfd {
 677         struct list_head     list;
 678         u64                  addr;
 679         int                  length;
 680         struct eventfd_ctx  *eventfd;
 681         u64                  datamatch;
 682         struct kvm_io_device dev;
 683         u8                   bus_idx;
 684         bool                 wildcard;
 685 };
 686
 687 static inline struct _ioeventfd *
 688 to_ioeventfd(struct kvm_io_device *dev)
 689 {
 690         return container_of(dev, struct _ioeventfd, dev);
 691 }
 692
 693 static void
 694 ioeventfd_release(struct _ioeventfd *p)
 695 {
 696         eventfd_ctx_put(p->eventfd);
 697         list_del(&p->list);
 698         kfree(p);
 699 }
 700
 701 static bool
 702 ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
 703 {
 704         u64 _val;
 705
 706         if (addr != p->addr)
 707                 /* address must be precise for a hit */
 708                 return false;
 709
 710         if (!p->length)
 711                 /* length = 0 means only look at the address, so always a hit */
 712                 return true;
 713
 714         if (len != p->length)
 715                 /* address-range must be precise for a hit */
 716                 return false;
 717
 718         if (p->wildcard)
 719                 /* all else equal, wildcard is always a hit */
 720                 return true;
 721
 722         /* otherwise, we have to actually compare the data */
 723
 724         BUG_ON(!IS_ALIGNED((unsigned long)val, len));
 725
 726         switch (len) {
 727         case 1:
 728                 _val = *(u8 *)val;
 729                 break;
 730         case 2:
 731                 _val = *(u16 *)val;
 732                 break;
 733         case 4:
 734                 _val = *(u32 *)val;
 735                 break;
 736         case 8:
 737                 _val = *(u64 *)val;
 738                 break;
 739         default:
 740                 return false;
 741         }
 742
 743         return _val == p->datamatch;
 744 }
 745
 746 /* MMIO/PIO writes trigger an event if the addr/val match */
 747 static int
 748 ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr,
 749                 int len, const void *val)
 750 {
 751         struct _ioeventfd *p = to_ioeventfd(this);
 752
 753         if (!ioeventfd_in_range(p, addr, len, val))
 754                 return -EOPNOTSUPP;
 755
 756         eventfd_signal(p->eventfd, 1);
 757         return 0;
 758 }
 759
 760 /*
 761  * This function is called as KVM is completely shutting down.  We do not
 762  * need to worry about locking just nuke anything we have as quickly as possible
 763  */
 764 static void
 765 ioeventfd_destructor(struct kvm_io_device *this)
 766 {
 767         struct _ioeventfd *p = to_ioeventfd(this);
 768
 769         ioeventfd_release(p);
 770 }
 771
 772 static const struct kvm_io_device_ops ioeventfd_ops = {
 773         .write      = ioeventfd_write,
 774         .destructor = ioeventfd_destructor,
 775 };
 776
 777 /* assumes kvm->slots_lock held */
 778 static bool
 779 ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
 780 {
 781         struct _ioeventfd *_p;
 782
 783         list_for_each_entry(_p, &kvm->ioeventfds, list)
 784                 if (_p->bus_idx == p->bus_idx &&
 785                     _p->addr == p->addr &&
 786                     (!_p->length || !p->length ||
 787                      (_p->length == p->length &&
 788                       (_p->wildcard || p->wildcard ||
 789                        _p->datamatch == p->datamatch))))
 790                         return true;
 791
 792         return false;
 793 }
 794
 795 static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags)
 796 {
 797         if (flags & KVM_IOEVENTFD_FLAG_PIO)
 798                 return KVM_PIO_BUS;
 799         if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY)
 800                 return KVM_VIRTIO_CCW_NOTIFY_BUS;
 801         return KVM_MMIO_BUS;
 802 }
 803
 804 static int kvm_assign_ioeventfd_idx(struct kvm *kvm,
 805                                 enum kvm_bus bus_idx,
 806                                 struct kvm_ioeventfd *args)
 807 {
 808
 809         struct eventfd_ctx *eventfd;
 810         struct _ioeventfd *p;
 811         int ret;
 812
 813         eventfd = eventfd_ctx_fdget(args->fd);
 814         if (IS_ERR(eventfd))
 815                 return PTR_ERR(eventfd);
 816
 817         p = kzalloc(sizeof(*p), GFP_KERNEL_ACCOUNT);
 818         if (!p) {
 819                 ret = -ENOMEM;
 820                 goto fail;
 821         }
 822
 823         INIT_LIST_HEAD(&p->list);
 824         p->addr    = args->addr;
 825         p->bus_idx = bus_idx;
 826         p->length  = args->len;
 827         p->eventfd = eventfd;
 828
 829         /* The datamatch feature is optional, otherwise this is a wildcard */
 830         if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
 831                 p->datamatch = args->datamatch;
 832         else
 833                 p->wildcard = true;
 834
 835         mutex_lock(&kvm->slots_lock);
 836
 837         /* Verify that there isn't a match already */
 838         if (ioeventfd_check_collision(kvm, p)) {
 839                 ret = -EEXIST;
 840                 goto unlock_fail;
 841         }
 842
 843         kvm_iodevice_init(&p->dev, &ioeventfd_ops);
 844
 845         ret = kvm_io_bus_register_dev(kvm, bus_idx, p->addr, p->length,
 846                                       &p->dev);
 847         if (ret < 0)
 848                 goto unlock_fail;
 849
 850         kvm_get_bus(kvm, bus_idx)->ioeventfd_count++;
 851         list_add_tail(&p->list, &kvm->ioeventfds);
 852
 853         mutex_unlock(&kvm->slots_lock);
 854
 855         return 0;
 856
 857 unlock_fail:
 858         mutex_unlock(&kvm->slots_lock);
 859
 860 fail:
 861         kfree(p);
 862         eventfd_ctx_put(eventfd);
 863
 864         return ret;
 865 }
 866
 867 static int
 868 kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
 869                            struct kvm_ioeventfd *args)
 870 {
 871         struct _ioeventfd        *p, *tmp;
 872         struct eventfd_ctx       *eventfd;
 873         struct kvm_io_bus        *bus;
 874         int                       ret = -ENOENT;
 875         bool                      wildcard;
 876
 877         eventfd = eventfd_ctx_fdget(args->fd);
 878         if (IS_ERR(eventfd))
 879                 return PTR_ERR(eventfd);
 880
 881         wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
 882
 883         mutex_lock(&kvm->slots_lock);
 884
 885         list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
 886
 887                 if (p->bus_idx != bus_idx ||
 888                     p->eventfd != eventfd  ||
 889                     p->addr != args->addr  ||
 890                     p->length != args->len ||
 891                     p->wildcard != wildcard)
 892                         continue;
 893
 894                 if (!p->wildcard && p->datamatch != args->datamatch)
 895                         continue;
 896
 897                 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
 898                 bus = kvm_get_bus(kvm, bus_idx);
 899                 if (bus)
 900                         bus->ioeventfd_count--;
 901                 ioeventfd_release(p);
 902                 ret = 0;
 903                 break;
 904         }
 905
 906         mutex_unlock(&kvm->slots_lock);
 907
 908         eventfd_ctx_put(eventfd);
 909
 910         return ret;
 911 }
 912
 913 static int kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 914 {
 915         enum kvm_bus bus_idx = ioeventfd_bus_from_flags(args->flags);
 916         int ret = kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
 917
 918         if (!args->len && bus_idx == KVM_MMIO_BUS)
 919                 kvm_deassign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
 920
 921         return ret;
 922 }
 923
 924 static int
 925 kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 926 {
 927         enum kvm_bus              bus_idx;
 928         int ret;
 929
 930         bus_idx = ioeventfd_bus_from_flags(args->flags);
 931         /* must be natural-word sized, or 0 to ignore length */
 932         switch (args->len) {
 933         case 0:
 934         case 1:
 935         case 2:
 936         case 4:
 937         case 8:
 938                 break;
 939         default:
 940                 return -EINVAL;
 941         }
 942
 943         /* check for range overflow */
 944         if (args->addr + args->len < args->addr)
 945                 return -EINVAL;
 946
 947         /* check for extra flags that we don't understand */
 948         if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
 949                 return -EINVAL;
 950
 951         /* ioeventfd with no length can't be combined with DATAMATCH */
 952         if (!args->len && (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH))
 953                 return -EINVAL;
 954
 955         ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args);
 956         if (ret)
 957                 goto fail;
 958
 959         /* When length is ignored, MMIO is also put on a separate bus, for
 960          * faster lookups.
 961          */
 962         if (!args->len && bus_idx == KVM_MMIO_BUS) {
 963                 ret = kvm_assign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
 964                 if (ret < 0)
 965                         goto fast_fail;
 966         }
 967
 968         return 0;
 969
 970 fast_fail:
 971         kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
 972 fail:
 973         return ret;
 974 }
 975
 976 int
 977 kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 978 {
 979         if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
 980                 return kvm_deassign_ioeventfd(kvm, args);
 981
 982         return kvm_assign_ioeventfd(kvm, args);
 983 }