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 static void irqfd_resampler_notify(struct kvm_kernel_irqfd_resampler *resampler)
  59 {
  60         struct kvm_kernel_irqfd *irqfd;
  61
  62         list_for_each_entry_srcu(irqfd, &resampler->list, resampler_link,
  63                                  srcu_read_lock_held(&resampler->kvm->irq_srcu))
  64                 eventfd_signal(irqfd->resamplefd, 1);
  65 }
  66
  67 /*
  68  * Since resampler irqfds share an IRQ source ID, we de-assert once
  69  * then notify all of the resampler irqfds using this GSI.  We can't
  70  * do multiple de-asserts or we risk racing with incoming re-asserts.
  71  */
  72 static void
  73 irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian)
  74 {
  75         struct kvm_kernel_irqfd_resampler *resampler;
  76         struct kvm *kvm;
  77         int idx;
  78
  79         resampler = container_of(kian,
  80                         struct kvm_kernel_irqfd_resampler, notifier);
  81         kvm = resampler->kvm;
  82
  83         kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
  84                     resampler->notifier.gsi, 0, false);
  85
  86         idx = srcu_read_lock(&kvm->irq_srcu);
  87         irqfd_resampler_notify(resampler);
  88         srcu_read_unlock(&kvm->irq_srcu, idx);
  89 }
  90
  91 static void
  92 irqfd_resampler_shutdown(struct kvm_kernel_irqfd *irqfd)
  93 {
  94         struct kvm_kernel_irqfd_resampler *resampler = irqfd->resampler;
  95         struct kvm *kvm = resampler->kvm;
  96
  97         mutex_lock(&kvm->irqfds.resampler_lock);
  98
  99         list_del_rcu(&irqfd->resampler_link);
 100         synchronize_srcu(&kvm->irq_srcu);
 101
 102         if (list_empty(&resampler->list)) {
 103                 list_del_rcu(&resampler->link);
 104                 kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier);
 105                 /*
 106                  * synchronize_srcu(&kvm->irq_srcu) already called
 107                  * in kvm_unregister_irq_ack_notifier().
 108                  */
 109                 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
 110                             resampler->notifier.gsi, 0, false);
 111                 kfree(resampler);
 112         }
 113
 114         mutex_unlock(&kvm->irqfds.resampler_lock);
 115 }
 116
 117 /*
 118  * Race-free decouple logic (ordering is critical)
 119  */
 120 static void
 121 irqfd_shutdown(struct work_struct *work)
 122 {
 123         struct kvm_kernel_irqfd *irqfd =
 124                 container_of(work, struct kvm_kernel_irqfd, shutdown);
 125         struct kvm *kvm = irqfd->kvm;
 126         u64 cnt;
 127
 128         /* Make sure irqfd has been initialized in assign path. */
 129         synchronize_srcu(&kvm->irq_srcu);
 130
 131         /*
 132          * Synchronize with the wait-queue and unhook ourselves to prevent
 133          * further events.
 134          */
 135         eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
 136
 137         /*
 138          * We know no new events will be scheduled at this point, so block
 139          * until all previously outstanding events have completed
 140          */
 141         flush_work(&irqfd->inject);
 142
 143         if (irqfd->resampler) {
 144                 irqfd_resampler_shutdown(irqfd);
 145                 eventfd_ctx_put(irqfd->resamplefd);
 146         }
 147
 148         /*
 149          * It is now safe to release the object's resources
 150          */
 151 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
 152         irq_bypass_unregister_consumer(&irqfd->consumer);
 153 #endif
 154         eventfd_ctx_put(irqfd->eventfd);
 155         kfree(irqfd);
 156 }
 157
 158
 159 /* assumes kvm->irqfds.lock is held */
 160 static bool
 161 irqfd_is_active(struct kvm_kernel_irqfd *irqfd)
 162 {
 163         return list_empty(&irqfd->list) ? false : true;
 164 }
 165
 166 /*
 167  * Mark the irqfd as inactive and schedule it for removal
 168  *
 169  * assumes kvm->irqfds.lock is held
 170  */
 171 static void
 172 irqfd_deactivate(struct kvm_kernel_irqfd *irqfd)
 173 {
 174         BUG_ON(!irqfd_is_active(irqfd));
 175
 176         list_del_init(&irqfd->list);
 177
 178         queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
 179 }
 180
 181 int __attribute__((weak)) kvm_arch_set_irq_inatomic(
 182                                 struct kvm_kernel_irq_routing_entry *irq,
 183                                 struct kvm *kvm, int irq_source_id,
 184                                 int level,
 185                                 bool line_status)
 186 {
 187         return -EWOULDBLOCK;
 188 }
 189
 190 /*
 191  * Called with wqh->lock held and interrupts disabled
 192  */
 193 static int
 194 irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
 195 {
 196         struct kvm_kernel_irqfd *irqfd =
 197                 container_of(wait, struct kvm_kernel_irqfd, wait);
 198         __poll_t flags = key_to_poll(key);
 199         struct kvm_kernel_irq_routing_entry irq;
 200         struct kvm *kvm = irqfd->kvm;
 201         unsigned seq;
 202         int idx;
 203         int ret = 0;
 204
 205         if (flags & EPOLLIN) {
 206                 u64 cnt;
 207                 eventfd_ctx_do_read(irqfd->eventfd, &cnt);
 208
 209                 idx = srcu_read_lock(&kvm->irq_srcu);
 210                 do {
 211                         seq = read_seqcount_begin(&irqfd->irq_entry_sc);
 212                         irq = irqfd->irq_entry;
 213                 } while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
 214                 /* An event has been signaled, inject an interrupt */
 215                 if (kvm_arch_set_irq_inatomic(&irq, kvm,
 216                                               KVM_USERSPACE_IRQ_SOURCE_ID, 1,
 217                                               false) == -EWOULDBLOCK)
 218                         schedule_work(&irqfd->inject);
 219                 srcu_read_unlock(&kvm->irq_srcu, idx);
 220                 ret = 1;
 221         }
 222
 223         if (flags & EPOLLHUP) {
 224                 /* The eventfd is closing, detach from KVM */
 225                 unsigned long iflags;
 226
 227                 spin_lock_irqsave(&kvm->irqfds.lock, iflags);
 228
 229                 /*
 230                  * We must check if someone deactivated the irqfd before
 231                  * we could acquire the irqfds.lock since the item is
 232                  * deactivated from the KVM side before it is unhooked from
 233                  * the wait-queue.  If it is already deactivated, we can
 234                  * simply return knowing the other side will cleanup for us.
 235                  * We cannot race against the irqfd going away since the
 236                  * other side is required to acquire wqh->lock, which we hold
 237                  */
 238                 if (irqfd_is_active(irqfd))
 239                         irqfd_deactivate(irqfd);
 240
 241                 spin_unlock_irqrestore(&kvm->irqfds.lock, iflags);
 242         }
 243
 244         return ret;
 245 }
 246
 247 static void
 248 irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
 249                         poll_table *pt)
 250 {
 251         struct kvm_kernel_irqfd *irqfd =
 252                 container_of(pt, struct kvm_kernel_irqfd, pt);
 253         add_wait_queue_priority(wqh, &irqfd->wait);
 254 }
 255
 256 /* Must be called under irqfds.lock */
 257 static void irqfd_update(struct kvm *kvm, struct kvm_kernel_irqfd *irqfd)
 258 {
 259         struct kvm_kernel_irq_routing_entry *e;
 260         struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
 261         int n_entries;
 262
 263         n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);
 264
 265         write_seqcount_begin(&irqfd->irq_entry_sc);
 266
 267         e = entries;
 268         if (n_entries == 1)
 269                 irqfd->irq_entry = *e;
 270         else
 271                 irqfd->irq_entry.type = 0;
 272
 273         write_seqcount_end(&irqfd->irq_entry_sc);
 274 }
 275
 276 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
 277 void __attribute__((weak)) kvm_arch_irq_bypass_stop(
 278                                 struct irq_bypass_consumer *cons)
 279 {
 280 }
 281
 282 void __attribute__((weak)) kvm_arch_irq_bypass_start(
 283                                 struct irq_bypass_consumer *cons)
 284 {
 285 }
 286
 287 int  __attribute__((weak)) kvm_arch_update_irqfd_routing(
 288                                 struct kvm *kvm, unsigned int host_irq,
 289                                 uint32_t guest_irq, bool set)
 290 {
 291         return 0;
 292 }
 293
 294 bool __attribute__((weak)) kvm_arch_irqfd_route_changed(
 295                                 struct kvm_kernel_irq_routing_entry *old,
 296                                 struct kvm_kernel_irq_routing_entry *new)
 297 {
 298         return true;
 299 }
 300 #endif
 301
 302 static int
 303 kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
 304 {
 305         struct kvm_kernel_irqfd *irqfd, *tmp;
 306         struct fd f;
 307         struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
 308         int ret;
 309         __poll_t events;
 310         int idx;
 311
 312         if (!kvm_arch_intc_initialized(kvm))
 313                 return -EAGAIN;
 314
 315         if (!kvm_arch_irqfd_allowed(kvm, args))
 316                 return -EINVAL;
 317
 318         irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL_ACCOUNT);
 319         if (!irqfd)
 320                 return -ENOMEM;
 321
 322         irqfd->kvm = kvm;
 323         irqfd->gsi = args->gsi;
 324         INIT_LIST_HEAD(&irqfd->list);
 325         INIT_WORK(&irqfd->inject, irqfd_inject);
 326         INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
 327         seqcount_spinlock_init(&irqfd->irq_entry_sc, &kvm->irqfds.lock);
 328
 329         f = fdget(args->fd);
 330         if (!f.file) {
 331                 ret = -EBADF;
 332                 goto out;
 333         }
 334
 335         eventfd = eventfd_ctx_fileget(f.file);
 336         if (IS_ERR(eventfd)) {
 337                 ret = PTR_ERR(eventfd);
 338                 goto fail;
 339         }
 340
 341         irqfd->eventfd = eventfd;
 342
 343         if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) {
 344                 struct kvm_kernel_irqfd_resampler *resampler;
 345
 346                 resamplefd = eventfd_ctx_fdget(args->resamplefd);
 347                 if (IS_ERR(resamplefd)) {
 348                         ret = PTR_ERR(resamplefd);
 349                         goto fail;
 350                 }
 351
 352                 irqfd->resamplefd = resamplefd;
 353                 INIT_LIST_HEAD(&irqfd->resampler_link);
 354
 355                 mutex_lock(&kvm->irqfds.resampler_lock);
 356
 357                 list_for_each_entry(resampler,
 358                                     &kvm->irqfds.resampler_list, link) {
 359                         if (resampler->notifier.gsi == irqfd->gsi) {
 360                                 irqfd->resampler = resampler;
 361                                 break;
 362                         }
 363                 }
 364
 365                 if (!irqfd->resampler) {
 366                         resampler = kzalloc(sizeof(*resampler),
 367                                             GFP_KERNEL_ACCOUNT);
 368                         if (!resampler) {
 369                                 ret = -ENOMEM;
 370                                 mutex_unlock(&kvm->irqfds.resampler_lock);
 371                                 goto fail;
 372                         }
 373
 374                         resampler->kvm = kvm;
 375                         INIT_LIST_HEAD(&resampler->list);
 376                         resampler->notifier.gsi = irqfd->gsi;
 377                         resampler->notifier.irq_acked = irqfd_resampler_ack;
 378                         INIT_LIST_HEAD(&resampler->link);
 379
 380                         list_add_rcu(&resampler->link, &kvm->irqfds.resampler_list);
 381                         kvm_register_irq_ack_notifier(kvm,
 382                                                       &resampler->notifier);
 383                         irqfd->resampler = resampler;
 384                 }
 385
 386                 list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list);
 387                 synchronize_srcu(&kvm->irq_srcu);
 388
 389                 mutex_unlock(&kvm->irqfds.resampler_lock);
 390         }
 391
 392         /*
 393          * Install our own custom wake-up handling so we are notified via
 394          * a callback whenever someone signals the underlying eventfd
 395          */
 396         init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
 397         init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
 398
 399         spin_lock_irq(&kvm->irqfds.lock);
 400
 401         ret = 0;
 402         list_for_each_entry(tmp, &kvm->irqfds.items, list) {
 403                 if (irqfd->eventfd != tmp->eventfd)
 404                         continue;
 405                 /* This fd is used for another irq already. */
 406                 ret = -EBUSY;
 407                 spin_unlock_irq(&kvm->irqfds.lock);
 408                 goto fail;
 409         }
 410
 411         idx = srcu_read_lock(&kvm->irq_srcu);
 412         irqfd_update(kvm, irqfd);
 413
 414         list_add_tail(&irqfd->list, &kvm->irqfds.items);
 415
 416         spin_unlock_irq(&kvm->irqfds.lock);
 417
 418         /*
 419          * Check if there was an event already pending on the eventfd
 420          * before we registered, and trigger it as if we didn't miss it.
 421          */
 422         events = vfs_poll(f.file, &irqfd->pt);
 423
 424         if (events & EPOLLIN)
 425                 schedule_work(&irqfd->inject);
 426
 427 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
 428         if (kvm_arch_has_irq_bypass()) {
 429                 irqfd->consumer.token = (void *)irqfd->eventfd;
 430                 irqfd->consumer.add_producer = kvm_arch_irq_bypass_add_producer;
 431                 irqfd->consumer.del_producer = kvm_arch_irq_bypass_del_producer;
 432                 irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
 433                 irqfd->consumer.start = kvm_arch_irq_bypass_start;
 434                 ret = irq_bypass_register_consumer(&irqfd->consumer);
 435                 if (ret)
 436                         pr_info("irq bypass consumer (token %p) registration fails: %d\n",
 437                                 irqfd->consumer.token, ret);
 438         }
 439 #endif
 440
 441         srcu_read_unlock(&kvm->irq_srcu, idx);
 442
 443         /*
 444          * do not drop the file until the irqfd is fully initialized, otherwise
 445          * we might race against the EPOLLHUP
 446          */
 447         fdput(f);
 448         return 0;
 449
 450 fail:
 451         if (irqfd->resampler)
 452                 irqfd_resampler_shutdown(irqfd);
 453
 454         if (resamplefd && !IS_ERR(resamplefd))
 455                 eventfd_ctx_put(resamplefd);
 456
 457         if (eventfd && !IS_ERR(eventfd))
 458                 eventfd_ctx_put(eventfd);
 459
 460         fdput(f);
 461
 462 out:
 463         kfree(irqfd);
 464         return ret;
 465 }
 466
 467 bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin)
 468 {
 469         struct kvm_irq_ack_notifier *kian;
 470         int gsi, idx;
 471
 472         idx = srcu_read_lock(&kvm->irq_srcu);
 473         gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
 474         if (gsi != -1)
 475                 hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list,
 476                                           link, srcu_read_lock_held(&kvm->irq_srcu))
 477                         if (kian->gsi == gsi) {
 478                                 srcu_read_unlock(&kvm->irq_srcu, idx);
 479                                 return true;
 480                         }
 481
 482         srcu_read_unlock(&kvm->irq_srcu, idx);
 483
 484         return false;
 485 }
 486 EXPORT_SYMBOL_GPL(kvm_irq_has_notifier);
 487
 488 void kvm_notify_acked_gsi(struct kvm *kvm, int gsi)
 489 {
 490         struct kvm_irq_ack_notifier *kian;
 491
 492         hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list,
 493                                   link, srcu_read_lock_held(&kvm->irq_srcu))
 494                 if (kian->gsi == gsi)
 495                         kian->irq_acked(kian);
 496 }
 497
 498 void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
 499 {
 500         int gsi, idx;
 501
 502         trace_kvm_ack_irq(irqchip, pin);
 503
 504         idx = srcu_read_lock(&kvm->irq_srcu);
 505         gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
 506         if (gsi != -1)
 507                 kvm_notify_acked_gsi(kvm, gsi);
 508         srcu_read_unlock(&kvm->irq_srcu, idx);
 509 }
 510
 511 void kvm_register_irq_ack_notifier(struct kvm *kvm,
 512                                    struct kvm_irq_ack_notifier *kian)
 513 {
 514         mutex_lock(&kvm->irq_lock);
 515         hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list);
 516         mutex_unlock(&kvm->irq_lock);
 517         kvm_arch_post_irq_ack_notifier_list_update(kvm);
 518 }
 519
 520 void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
 521                                     struct kvm_irq_ack_notifier *kian)
 522 {
 523         mutex_lock(&kvm->irq_lock);
 524         hlist_del_init_rcu(&kian->link);
 525         mutex_unlock(&kvm->irq_lock);
 526         synchronize_srcu(&kvm->irq_srcu);
 527         kvm_arch_post_irq_ack_notifier_list_update(kvm);
 528 }
 529 #endif
 530
 531 void
 532 kvm_eventfd_init(struct kvm *kvm)
 533 {
 534 #ifdef CONFIG_HAVE_KVM_IRQFD
 535         spin_lock_init(&kvm->irqfds.lock);
 536         INIT_LIST_HEAD(&kvm->irqfds.items);
 537         INIT_LIST_HEAD(&kvm->irqfds.resampler_list);
 538         mutex_init(&kvm->irqfds.resampler_lock);
 539 #endif
 540         INIT_LIST_HEAD(&kvm->ioeventfds);
 541 }
 542
 543 #ifdef CONFIG_HAVE_KVM_IRQFD
 544 /*
 545  * shutdown any irqfd's that match fd+gsi
 546  */
 547 static int
 548 kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
 549 {
 550         struct kvm_kernel_irqfd *irqfd, *tmp;
 551         struct eventfd_ctx *eventfd;
 552
 553         eventfd = eventfd_ctx_fdget(args->fd);
 554         if (IS_ERR(eventfd))
 555                 return PTR_ERR(eventfd);
 556
 557         spin_lock_irq(&kvm->irqfds.lock);
 558
 559         list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
 560                 if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) {
 561                         /*
 562                          * This clearing of irq_entry.type is needed for when
 563                          * another thread calls kvm_irq_routing_update before
 564                          * we flush workqueue below (we synchronize with
 565                          * kvm_irq_routing_update using irqfds.lock).
 566                          */
 567                         write_seqcount_begin(&irqfd->irq_entry_sc);
 568                         irqfd->irq_entry.type = 0;
 569                         write_seqcount_end(&irqfd->irq_entry_sc);
 570                         irqfd_deactivate(irqfd);
 571                 }
 572         }
 573
 574         spin_unlock_irq(&kvm->irqfds.lock);
 575         eventfd_ctx_put(eventfd);
 576
 577         /*
 578          * Block until we know all outstanding shutdown jobs have completed
 579          * so that we guarantee there will not be any more interrupts on this
 580          * gsi once this deassign function returns.
 581          */
 582         flush_workqueue(irqfd_cleanup_wq);
 583
 584         return 0;
 585 }
 586
 587 int
 588 kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
 589 {
 590         if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE))
 591                 return -EINVAL;
 592
 593         if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
 594                 return kvm_irqfd_deassign(kvm, args);
 595
 596         return kvm_irqfd_assign(kvm, args);
 597 }
 598
 599 /*
 600  * This function is called as the kvm VM fd is being released. Shutdown all
 601  * irqfds that still remain open
 602  */
 603 void
 604 kvm_irqfd_release(struct kvm *kvm)
 605 {
 606         struct kvm_kernel_irqfd *irqfd, *tmp;
 607
 608         spin_lock_irq(&kvm->irqfds.lock);
 609
 610         list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
 611                 irqfd_deactivate(irqfd);
 612
 613         spin_unlock_irq(&kvm->irqfds.lock);
 614
 615         /*
 616          * Block until we know all outstanding shutdown jobs have completed
 617          * since we do not take a kvm* reference.
 618          */
 619         flush_workqueue(irqfd_cleanup_wq);
 620
 621 }
 622
 623 /*
 624  * Take note of a change in irq routing.
 625  * Caller must invoke synchronize_srcu(&kvm->irq_srcu) afterwards.
 626  */
 627 void kvm_irq_routing_update(struct kvm *kvm)
 628 {
 629         struct kvm_kernel_irqfd *irqfd;
 630
 631         spin_lock_irq(&kvm->irqfds.lock);
 632
 633         list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
 634 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
 635                 /* Under irqfds.lock, so can read irq_entry safely */
 636                 struct kvm_kernel_irq_routing_entry old = irqfd->irq_entry;
 637 #endif
 638
 639                 irqfd_update(kvm, irqfd);
 640
 641 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
 642                 if (irqfd->producer &&
 643                     kvm_arch_irqfd_route_changed(&old, &irqfd->irq_entry)) {
 644                         int ret = kvm_arch_update_irqfd_routing(
 645                                         irqfd->kvm, irqfd->producer->irq,
 646                                         irqfd->gsi, 1);
 647                         WARN_ON(ret);
 648                 }
 649 #endif
 650         }
 651
 652         spin_unlock_irq(&kvm->irqfds.lock);
 653 }
 654
 655 bool kvm_notify_irqfd_resampler(struct kvm *kvm,
 656                                 unsigned int irqchip,
 657                                 unsigned int pin)
 658 {
 659         struct kvm_kernel_irqfd_resampler *resampler;
 660         int gsi, idx;
 661
 662         idx = srcu_read_lock(&kvm->irq_srcu);
 663         gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
 664         if (gsi != -1) {
 665                 list_for_each_entry_srcu(resampler,
 666                                          &kvm->irqfds.resampler_list, link,
 667                                          srcu_read_lock_held(&kvm->irq_srcu)) {
 668                         if (resampler->notifier.gsi == gsi) {
 669                                 irqfd_resampler_notify(resampler);
 670                                 srcu_read_unlock(&kvm->irq_srcu, idx);
 671                                 return true;
 672                         }
 673                 }
 674         }
 675         srcu_read_unlock(&kvm->irq_srcu, idx);
 676
 677         return false;
 678 }
 679
 680 /*
 681  * create a host-wide workqueue for issuing deferred shutdown requests
 682  * aggregated from all vm* instances. We need our own isolated
 683  * queue to ease flushing work items when a VM exits.
 684  */
 685 int kvm_irqfd_init(void)
 686 {
 687         irqfd_cleanup_wq = alloc_workqueue("kvm-irqfd-cleanup", 0, 0);
 688         if (!irqfd_cleanup_wq)
 689                 return -ENOMEM;
 690
 691         return 0;
 692 }
 693
 694 void kvm_irqfd_exit(void)
 695 {
 696         destroy_workqueue(irqfd_cleanup_wq);
 697 }
 698 #endif
 699
 700 /*
 701  * --------------------------------------------------------------------
 702  * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
 703  *
 704  * userspace can register a PIO/MMIO address with an eventfd for receiving
 705  * notification when the memory has been touched.
 706  * --------------------------------------------------------------------
 707  */
 708
 709 struct _ioeventfd {
 710         struct list_head     list;
 711         u64                  addr;
 712         int                  length;
 713         struct eventfd_ctx  *eventfd;
 714         u64                  datamatch;
 715         struct kvm_io_device dev;
 716         u8                   bus_idx;
 717         bool                 wildcard;
 718 };
 719
 720 static inline struct _ioeventfd *
 721 to_ioeventfd(struct kvm_io_device *dev)
 722 {
 723         return container_of(dev, struct _ioeventfd, dev);
 724 }
 725
 726 static void
 727 ioeventfd_release(struct _ioeventfd *p)
 728 {
 729         eventfd_ctx_put(p->eventfd);
 730         list_del(&p->list);
 731         kfree(p);
 732 }
 733
 734 static bool
 735 ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
 736 {
 737         u64 _val;
 738
 739         if (addr != p->addr)
 740                 /* address must be precise for a hit */
 741                 return false;
 742
 743         if (!p->length)
 744                 /* length = 0 means only look at the address, so always a hit */
 745                 return true;
 746
 747         if (len != p->length)
 748                 /* address-range must be precise for a hit */
 749                 return false;
 750
 751         if (p->wildcard)
 752                 /* all else equal, wildcard is always a hit */
 753                 return true;
 754
 755         /* otherwise, we have to actually compare the data */
 756
 757         BUG_ON(!IS_ALIGNED((unsigned long)val, len));
 758
 759         switch (len) {
 760         case 1:
 761                 _val = *(u8 *)val;
 762                 break;
 763         case 2:
 764                 _val = *(u16 *)val;
 765                 break;
 766         case 4:
 767                 _val = *(u32 *)val;
 768                 break;
 769         case 8:
 770                 _val = *(u64 *)val;
 771                 break;
 772         default:
 773                 return false;
 774         }
 775
 776         return _val == p->datamatch;
 777 }
 778
 779 /* MMIO/PIO writes trigger an event if the addr/val match */
 780 static int
 781 ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr,
 782                 int len, const void *val)
 783 {
 784         struct _ioeventfd *p = to_ioeventfd(this);
 785
 786         if (!ioeventfd_in_range(p, addr, len, val))
 787                 return -EOPNOTSUPP;
 788
 789         eventfd_signal(p->eventfd, 1);
 790         return 0;
 791 }
 792
 793 /*
 794  * This function is called as KVM is completely shutting down.  We do not
 795  * need to worry about locking just nuke anything we have as quickly as possible
 796  */
 797 static void
 798 ioeventfd_destructor(struct kvm_io_device *this)
 799 {
 800         struct _ioeventfd *p = to_ioeventfd(this);
 801
 802         ioeventfd_release(p);
 803 }
 804
 805 static const struct kvm_io_device_ops ioeventfd_ops = {
 806         .write      = ioeventfd_write,
 807         .destructor = ioeventfd_destructor,
 808 };
 809
 810 /* assumes kvm->slots_lock held */
 811 static bool
 812 ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
 813 {
 814         struct _ioeventfd *_p;
 815
 816         list_for_each_entry(_p, &kvm->ioeventfds, list)
 817                 if (_p->bus_idx == p->bus_idx &&
 818                     _p->addr == p->addr &&
 819                     (!_p->length || !p->length ||
 820                      (_p->length == p->length &&
 821                       (_p->wildcard || p->wildcard ||
 822                        _p->datamatch == p->datamatch))))
 823                         return true;
 824
 825         return false;
 826 }
 827
 828 static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags)
 829 {
 830         if (flags & KVM_IOEVENTFD_FLAG_PIO)
 831                 return KVM_PIO_BUS;
 832         if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY)
 833                 return KVM_VIRTIO_CCW_NOTIFY_BUS;
 834         return KVM_MMIO_BUS;
 835 }
 836
 837 static int kvm_assign_ioeventfd_idx(struct kvm *kvm,
 838                                 enum kvm_bus bus_idx,
 839                                 struct kvm_ioeventfd *args)
 840 {
 841
 842         struct eventfd_ctx *eventfd;
 843         struct _ioeventfd *p;
 844         int ret;
 845
 846         eventfd = eventfd_ctx_fdget(args->fd);
 847         if (IS_ERR(eventfd))
 848                 return PTR_ERR(eventfd);
 849
 850         p = kzalloc(sizeof(*p), GFP_KERNEL_ACCOUNT);
 851         if (!p) {
 852                 ret = -ENOMEM;
 853                 goto fail;
 854         }
 855
 856         INIT_LIST_HEAD(&p->list);
 857         p->addr    = args->addr;
 858         p->bus_idx = bus_idx;
 859         p->length  = args->len;
 860         p->eventfd = eventfd;
 861
 862         /* The datamatch feature is optional, otherwise this is a wildcard */
 863         if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
 864                 p->datamatch = args->datamatch;
 865         else
 866                 p->wildcard = true;
 867
 868         mutex_lock(&kvm->slots_lock);
 869
 870         /* Verify that there isn't a match already */
 871         if (ioeventfd_check_collision(kvm, p)) {
 872                 ret = -EEXIST;
 873                 goto unlock_fail;
 874         }
 875
 876         kvm_iodevice_init(&p->dev, &ioeventfd_ops);
 877
 878         ret = kvm_io_bus_register_dev(kvm, bus_idx, p->addr, p->length,
 879                                       &p->dev);
 880         if (ret < 0)
 881                 goto unlock_fail;
 882
 883         kvm_get_bus(kvm, bus_idx)->ioeventfd_count++;
 884         list_add_tail(&p->list, &kvm->ioeventfds);
 885
 886         mutex_unlock(&kvm->slots_lock);
 887
 888         return 0;
 889
 890 unlock_fail:
 891         mutex_unlock(&kvm->slots_lock);
 892         kfree(p);
 893
 894 fail:
 895         eventfd_ctx_put(eventfd);
 896
 897         return ret;
 898 }
 899
 900 static int
 901 kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
 902                            struct kvm_ioeventfd *args)
 903 {
 904         struct _ioeventfd        *p;
 905         struct eventfd_ctx       *eventfd;
 906         struct kvm_io_bus        *bus;
 907         int                       ret = -ENOENT;
 908         bool                      wildcard;
 909
 910         eventfd = eventfd_ctx_fdget(args->fd);
 911         if (IS_ERR(eventfd))
 912                 return PTR_ERR(eventfd);
 913
 914         wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
 915
 916         mutex_lock(&kvm->slots_lock);
 917
 918         list_for_each_entry(p, &kvm->ioeventfds, list) {
 919                 if (p->bus_idx != bus_idx ||
 920                     p->eventfd != eventfd  ||
 921                     p->addr != args->addr  ||
 922                     p->length != args->len ||
 923                     p->wildcard != wildcard)
 924                         continue;
 925
 926                 if (!p->wildcard && p->datamatch != args->datamatch)
 927                         continue;
 928
 929                 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
 930                 bus = kvm_get_bus(kvm, bus_idx);
 931                 if (bus)
 932                         bus->ioeventfd_count--;
 933                 ret = 0;
 934                 break;
 935         }
 936
 937         mutex_unlock(&kvm->slots_lock);
 938
 939         eventfd_ctx_put(eventfd);
 940
 941         return ret;
 942 }
 943
 944 static int kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 945 {
 946         enum kvm_bus bus_idx = ioeventfd_bus_from_flags(args->flags);
 947         int ret = kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
 948
 949         if (!args->len && bus_idx == KVM_MMIO_BUS)
 950                 kvm_deassign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
 951
 952         return ret;
 953 }
 954
 955 static int
 956 kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 957 {
 958         enum kvm_bus              bus_idx;
 959         int ret;
 960
 961         bus_idx = ioeventfd_bus_from_flags(args->flags);
 962         /* must be natural-word sized, or 0 to ignore length */
 963         switch (args->len) {
 964         case 0:
 965         case 1:
 966         case 2:
 967         case 4:
 968         case 8:
 969                 break;
 970         default:
 971                 return -EINVAL;
 972         }
 973
 974         /* check for range overflow */
 975         if (args->addr + args->len < args->addr)
 976                 return -EINVAL;
 977
 978         /* check for extra flags that we don't understand */
 979         if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
 980                 return -EINVAL;
 981
 982         /* ioeventfd with no length can't be combined with DATAMATCH */
 983         if (!args->len && (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH))
 984                 return -EINVAL;
 985
 986         ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args);
 987         if (ret)
 988                 goto fail;
 989
 990         /* When length is ignored, MMIO is also put on a separate bus, for
 991          * faster lookups.
 992          */
 993         if (!args->len && bus_idx == KVM_MMIO_BUS) {
 994                 ret = kvm_assign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
 995                 if (ret < 0)
 996                         goto fast_fail;
 997         }
 998
 999         return 0;
1000
1001 fast_fail:
1002         kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
1003 fail:
1004         return ret;
1005 }
1006
1007 int
1008 kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
1009 {
1010         if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
1011                 return kvm_deassign_ioeventfd(kvm, args);
1012
1013         return kvm_assign_ioeventfd(kvm, args);
1014 }