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 <[email protected]>
  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_IRQCHIP
  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);
  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
 101         if (list_empty(&resampler->list)) {
 102                 list_del_rcu(&resampler->link);
 103                 kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier);
 104                 /*
 105                  * synchronize_srcu_expedited(&kvm->irq_srcu) already called
 106                  * in kvm_unregister_irq_ack_notifier().
 107                  */
 108                 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
 109                             resampler->notifier.gsi, 0, false);
 110                 kfree(resampler);
 111         } else {
 112                 synchronize_srcu_expedited(&kvm->irq_srcu);
 113         }
 114
 115         mutex_unlock(&kvm->irqfds.resampler_lock);
 116 }
 117
 118 /*
 119  * Race-free decouple logic (ordering is critical)
 120  */
 121 static void
 122 irqfd_shutdown(struct work_struct *work)
 123 {
 124         struct kvm_kernel_irqfd *irqfd =
 125                 container_of(work, struct kvm_kernel_irqfd, shutdown);
 126         struct kvm *kvm = irqfd->kvm;
 127         u64 cnt;
 128
 129         /* Make sure irqfd has been initialized in assign path. */
 130         synchronize_srcu_expedited(&kvm->irq_srcu);
 131
 132         /*
 133          * Synchronize with the wait-queue and unhook ourselves to prevent
 134          * further events.
 135          */
 136         eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
 137
 138         /*
 139          * We know no new events will be scheduled at this point, so block
 140          * until all previously outstanding events have completed
 141          */
 142         flush_work(&irqfd->inject);
 143
 144         if (irqfd->resampler) {
 145                 irqfd_resampler_shutdown(irqfd);
 146                 eventfd_ctx_put(irqfd->resamplefd);
 147         }
 148
 149         /*
 150          * It is now safe to release the object's resources
 151          */
 152 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
 153         irq_bypass_unregister_consumer(&irqfd->consumer);
 154 #endif
 155         eventfd_ctx_put(irqfd->eventfd);
 156         kfree(irqfd);
 157 }
 158
 159
 160 /* assumes kvm->irqfds.lock is held */
 161 static bool
 162 irqfd_is_active(struct kvm_kernel_irqfd *irqfd)
 163 {
 164         return list_empty(&irqfd->list) ? false : true;
 165 }
 166
 167 /*
 168  * Mark the irqfd as inactive and schedule it for removal
 169  *
 170  * assumes kvm->irqfds.lock is held
 171  */
 172 static void
 173 irqfd_deactivate(struct kvm_kernel_irqfd *irqfd)
 174 {
 175         BUG_ON(!irqfd_is_active(irqfd));
 176
 177         list_del_init(&irqfd->list);
 178
 179         queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
 180 }
 181
 182 int __attribute__((weak)) kvm_arch_set_irq_inatomic(
 183                                 struct kvm_kernel_irq_routing_entry *irq,
 184                                 struct kvm *kvm, int irq_source_id,
 185                                 int level,
 186                                 bool line_status)
 187 {
 188         return -EWOULDBLOCK;
 189 }
 190
 191 /*
 192  * Called with wqh->lock held and interrupts disabled
 193  */
 194 static int
 195 irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
 196 {
 197         struct kvm_kernel_irqfd *irqfd =
 198                 container_of(wait, struct kvm_kernel_irqfd, wait);
 199         __poll_t flags = key_to_poll(key);
 200         struct kvm_kernel_irq_routing_entry irq;
 201         struct kvm *kvm = irqfd->kvm;
 202         unsigned seq;
 203         int idx;
 204         int ret = 0;
 205
 206         if (flags & EPOLLIN) {
 207                 u64 cnt;
 208                 eventfd_ctx_do_read(irqfd->eventfd, &cnt);
 209
 210                 idx = srcu_read_lock(&kvm->irq_srcu);
 211                 do {
 212                         seq = read_seqcount_begin(&irqfd->irq_entry_sc);
 213                         irq = irqfd->irq_entry;
 214                 } while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
 215                 /* An event has been signaled, inject an interrupt */
 216                 if (kvm_arch_set_irq_inatomic(&irq, kvm,
 217                                               KVM_USERSPACE_IRQ_SOURCE_ID, 1,
 218                                               false) == -EWOULDBLOCK)
 219                         schedule_work(&irqfd->inject);
 220                 srcu_read_unlock(&kvm->irq_srcu, idx);
 221                 ret = 1;
 222         }
 223
 224         if (flags & EPOLLHUP) {
 225                 /* The eventfd is closing, detach from KVM */
 226                 unsigned long iflags;
 227
 228                 spin_lock_irqsave(&kvm->irqfds.lock, iflags);
 229
 230                 /*
 231                  * We must check if someone deactivated the irqfd before
 232                  * we could acquire the irqfds.lock since the item is
 233                  * deactivated from the KVM side before it is unhooked from
 234                  * the wait-queue.  If it is already deactivated, we can
 235                  * simply return knowing the other side will cleanup for us.
 236                  * We cannot race against the irqfd going away since the
 237                  * other side is required to acquire wqh->lock, which we hold
 238                  */
 239                 if (irqfd_is_active(irqfd))
 240                         irqfd_deactivate(irqfd);
 241
 242                 spin_unlock_irqrestore(&kvm->irqfds.lock, iflags);
 243         }
 244
 245         return ret;
 246 }
 247
 248 static void
 249 irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
 250                         poll_table *pt)
 251 {
 252         struct kvm_kernel_irqfd *irqfd =
 253                 container_of(pt, struct kvm_kernel_irqfd, pt);
 254         add_wait_queue_priority(wqh, &irqfd->wait);
 255 }
 256
 257 /* Must be called under irqfds.lock */
 258 static void irqfd_update(struct kvm *kvm, struct kvm_kernel_irqfd *irqfd)
 259 {
 260         struct kvm_kernel_irq_routing_entry *e;
 261         struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
 262         int n_entries;
 263
 264         n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);
 265
 266         write_seqcount_begin(&irqfd->irq_entry_sc);
 267
 268         e = entries;
 269         if (n_entries == 1)
 270                 irqfd->irq_entry = *e;
 271         else
 272                 irqfd->irq_entry.type = 0;
 273
 274         write_seqcount_end(&irqfd->irq_entry_sc);
 275 }
 276
 277 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
 278 void __attribute__((weak)) kvm_arch_irq_bypass_stop(
 279                                 struct irq_bypass_consumer *cons)
 280 {
 281 }
 282
 283 void __attribute__((weak)) kvm_arch_irq_bypass_start(
 284                                 struct irq_bypass_consumer *cons)
 285 {
 286 }
 287
 288 int  __attribute__((weak)) kvm_arch_update_irqfd_routing(
 289                                 struct kvm *kvm, unsigned int host_irq,
 290                                 uint32_t guest_irq, bool set)
 291 {
 292         return 0;
 293 }
 294
 295 bool __attribute__((weak)) kvm_arch_irqfd_route_changed(
 296                                 struct kvm_kernel_irq_routing_entry *old,
 297                                 struct kvm_kernel_irq_routing_entry *new)
 298 {
 299         return true;
 300 }
 301 #endif
 302
 303 static int
 304 kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
 305 {
 306         struct kvm_kernel_irqfd *irqfd, *tmp;
 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         CLASS(fd, f)(args->fd);
 330         if (fd_empty(f)) {
 331                 ret = -EBADF;
 332                 goto out;
 333         }
 334
 335         eventfd = eventfd_ctx_fileget(fd_file(f));
 336         if (IS_ERR(eventfd)) {
 337                 ret = PTR_ERR(eventfd);
 338                 goto out;
 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_expedited(&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(fd_file(f), &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         return 0;
 443
 444 fail:
 445         if (irqfd->resampler)
 446                 irqfd_resampler_shutdown(irqfd);
 447
 448         if (resamplefd && !IS_ERR(resamplefd))
 449                 eventfd_ctx_put(resamplefd);
 450
 451         if (eventfd && !IS_ERR(eventfd))
 452                 eventfd_ctx_put(eventfd);
 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_expedited(&kvm->irq_srcu);
 519         kvm_arch_post_irq_ack_notifier_list_update(kvm);
 520 }
 521
 522 /*
 523  * shutdown any irqfd's that match fd+gsi
 524  */
 525 static int
 526 kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
 527 {
 528         struct kvm_kernel_irqfd *irqfd, *tmp;
 529         struct eventfd_ctx *eventfd;
 530
 531         eventfd = eventfd_ctx_fdget(args->fd);
 532         if (IS_ERR(eventfd))
 533                 return PTR_ERR(eventfd);
 534
 535         spin_lock_irq(&kvm->irqfds.lock);
 536
 537         list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
 538                 if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) {
 539                         /*
 540                          * This clearing of irq_entry.type is needed for when
 541                          * another thread calls kvm_irq_routing_update before
 542                          * we flush workqueue below (we synchronize with
 543                          * kvm_irq_routing_update using irqfds.lock).
 544                          */
 545                         write_seqcount_begin(&irqfd->irq_entry_sc);
 546                         irqfd->irq_entry.type = 0;
 547                         write_seqcount_end(&irqfd->irq_entry_sc);
 548                         irqfd_deactivate(irqfd);
 549                 }
 550         }
 551
 552         spin_unlock_irq(&kvm->irqfds.lock);
 553         eventfd_ctx_put(eventfd);
 554
 555         /*
 556          * Block until we know all outstanding shutdown jobs have completed
 557          * so that we guarantee there will not be any more interrupts on this
 558          * gsi once this deassign function returns.
 559          */
 560         flush_workqueue(irqfd_cleanup_wq);
 561
 562         return 0;
 563 }
 564
 565 int
 566 kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
 567 {
 568         if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE))
 569                 return -EINVAL;
 570
 571         if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
 572                 return kvm_irqfd_deassign(kvm, args);
 573
 574         return kvm_irqfd_assign(kvm, args);
 575 }
 576
 577 /*
 578  * This function is called as the kvm VM fd is being released. Shutdown all
 579  * irqfds that still remain open
 580  */
 581 void
 582 kvm_irqfd_release(struct kvm *kvm)
 583 {
 584         struct kvm_kernel_irqfd *irqfd, *tmp;
 585
 586         spin_lock_irq(&kvm->irqfds.lock);
 587
 588         list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
 589                 irqfd_deactivate(irqfd);
 590
 591         spin_unlock_irq(&kvm->irqfds.lock);
 592
 593         /*
 594          * Block until we know all outstanding shutdown jobs have completed
 595          * since we do not take a kvm* reference.
 596          */
 597         flush_workqueue(irqfd_cleanup_wq);
 598
 599 }
 600
 601 /*
 602  * Take note of a change in irq routing.
 603  * Caller must invoke synchronize_srcu_expedited(&kvm->irq_srcu) afterwards.
 604  */
 605 void kvm_irq_routing_update(struct kvm *kvm)
 606 {
 607         struct kvm_kernel_irqfd *irqfd;
 608
 609         spin_lock_irq(&kvm->irqfds.lock);
 610
 611         list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
 612 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
 613                 /* Under irqfds.lock, so can read irq_entry safely */
 614                 struct kvm_kernel_irq_routing_entry old = irqfd->irq_entry;
 615 #endif
 616
 617                 irqfd_update(kvm, irqfd);
 618
 619 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
 620                 if (irqfd->producer &&
 621                     kvm_arch_irqfd_route_changed(&old, &irqfd->irq_entry)) {
 622                         int ret = kvm_arch_update_irqfd_routing(
 623                                         irqfd->kvm, irqfd->producer->irq,
 624                                         irqfd->gsi, 1);
 625                         WARN_ON(ret);
 626                 }
 627 #endif
 628         }
 629
 630         spin_unlock_irq(&kvm->irqfds.lock);
 631 }
 632
 633 bool kvm_notify_irqfd_resampler(struct kvm *kvm,
 634                                 unsigned int irqchip,
 635                                 unsigned int pin)
 636 {
 637         struct kvm_kernel_irqfd_resampler *resampler;
 638         int gsi, idx;
 639
 640         idx = srcu_read_lock(&kvm->irq_srcu);
 641         gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
 642         if (gsi != -1) {
 643                 list_for_each_entry_srcu(resampler,
 644                                          &kvm->irqfds.resampler_list, link,
 645                                          srcu_read_lock_held(&kvm->irq_srcu)) {
 646                         if (resampler->notifier.gsi == gsi) {
 647                                 irqfd_resampler_notify(resampler);
 648                                 srcu_read_unlock(&kvm->irq_srcu, idx);
 649                                 return true;
 650                         }
 651                 }
 652         }
 653         srcu_read_unlock(&kvm->irq_srcu, idx);
 654
 655         return false;
 656 }
 657
 658 /*
 659  * create a host-wide workqueue for issuing deferred shutdown requests
 660  * aggregated from all vm* instances. We need our own isolated
 661  * queue to ease flushing work items when a VM exits.
 662  */
 663 int kvm_irqfd_init(void)
 664 {
 665         irqfd_cleanup_wq = alloc_workqueue("kvm-irqfd-cleanup", 0, 0);
 666         if (!irqfd_cleanup_wq)
 667                 return -ENOMEM;
 668
 669         return 0;
 670 }
 671
 672 void kvm_irqfd_exit(void)
 673 {
 674         destroy_workqueue(irqfd_cleanup_wq);
 675 }
 676 #endif
 677
 678 /*
 679  * --------------------------------------------------------------------
 680  * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
 681  *
 682  * userspace can register a PIO/MMIO address with an eventfd for receiving
 683  * notification when the memory has been touched.
 684  * --------------------------------------------------------------------
 685  */
 686
 687 struct _ioeventfd {
 688         struct list_head     list;
 689         u64                  addr;
 690         int                  length;
 691         struct eventfd_ctx  *eventfd;
 692         u64                  datamatch;
 693         struct kvm_io_device dev;
 694         u8                   bus_idx;
 695         bool                 wildcard;
 696 };
 697
 698 static inline struct _ioeventfd *
 699 to_ioeventfd(struct kvm_io_device *dev)
 700 {
 701         return container_of(dev, struct _ioeventfd, dev);
 702 }
 703
 704 static void
 705 ioeventfd_release(struct _ioeventfd *p)
 706 {
 707         eventfd_ctx_put(p->eventfd);
 708         list_del(&p->list);
 709         kfree(p);
 710 }
 711
 712 static bool
 713 ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
 714 {
 715         u64 _val;
 716
 717         if (addr != p->addr)
 718                 /* address must be precise for a hit */
 719                 return false;
 720
 721         if (!p->length)
 722                 /* length = 0 means only look at the address, so always a hit */
 723                 return true;
 724
 725         if (len != p->length)
 726                 /* address-range must be precise for a hit */
 727                 return false;
 728
 729         if (p->wildcard)
 730                 /* all else equal, wildcard is always a hit */
 731                 return true;
 732
 733         /* otherwise, we have to actually compare the data */
 734
 735         BUG_ON(!IS_ALIGNED((unsigned long)val, len));
 736
 737         switch (len) {
 738         case 1:
 739                 _val = *(u8 *)val;
 740                 break;
 741         case 2:
 742                 _val = *(u16 *)val;
 743                 break;
 744         case 4:
 745                 _val = *(u32 *)val;
 746                 break;
 747         case 8:
 748                 _val = *(u64 *)val;
 749                 break;
 750         default:
 751                 return false;
 752         }
 753
 754         return _val == p->datamatch;
 755 }
 756
 757 /* MMIO/PIO writes trigger an event if the addr/val match */
 758 static int
 759 ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr,
 760                 int len, const void *val)
 761 {
 762         struct _ioeventfd *p = to_ioeventfd(this);
 763
 764         if (!ioeventfd_in_range(p, addr, len, val))
 765                 return -EOPNOTSUPP;
 766
 767         eventfd_signal(p->eventfd);
 768         return 0;
 769 }
 770
 771 /*
 772  * This function is called as KVM is completely shutting down.  We do not
 773  * need to worry about locking just nuke anything we have as quickly as possible
 774  */
 775 static void
 776 ioeventfd_destructor(struct kvm_io_device *this)
 777 {
 778         struct _ioeventfd *p = to_ioeventfd(this);
 779
 780         ioeventfd_release(p);
 781 }
 782
 783 static const struct kvm_io_device_ops ioeventfd_ops = {
 784         .write      = ioeventfd_write,
 785         .destructor = ioeventfd_destructor,
 786 };
 787
 788 /* assumes kvm->slots_lock held */
 789 static bool
 790 ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
 791 {
 792         struct _ioeventfd *_p;
 793
 794         list_for_each_entry(_p, &kvm->ioeventfds, list)
 795                 if (_p->bus_idx == p->bus_idx &&
 796                     _p->addr == p->addr &&
 797                     (!_p->length || !p->length ||
 798                      (_p->length == p->length &&
 799                       (_p->wildcard || p->wildcard ||
 800                        _p->datamatch == p->datamatch))))
 801                         return true;
 802
 803         return false;
 804 }
 805
 806 static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags)
 807 {
 808         if (flags & KVM_IOEVENTFD_FLAG_PIO)
 809                 return KVM_PIO_BUS;
 810         if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY)
 811                 return KVM_VIRTIO_CCW_NOTIFY_BUS;
 812         return KVM_MMIO_BUS;
 813 }
 814
 815 static int kvm_assign_ioeventfd_idx(struct kvm *kvm,
 816                                 enum kvm_bus bus_idx,
 817                                 struct kvm_ioeventfd *args)
 818 {
 819
 820         struct eventfd_ctx *eventfd;
 821         struct _ioeventfd *p;
 822         int ret;
 823
 824         eventfd = eventfd_ctx_fdget(args->fd);
 825         if (IS_ERR(eventfd))
 826                 return PTR_ERR(eventfd);
 827
 828         p = kzalloc(sizeof(*p), GFP_KERNEL_ACCOUNT);
 829         if (!p) {
 830                 ret = -ENOMEM;
 831                 goto fail;
 832         }
 833
 834         INIT_LIST_HEAD(&p->list);
 835         p->addr    = args->addr;
 836         p->bus_idx = bus_idx;
 837         p->length  = args->len;
 838         p->eventfd = eventfd;
 839
 840         /* The datamatch feature is optional, otherwise this is a wildcard */
 841         if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
 842                 p->datamatch = args->datamatch;
 843         else
 844                 p->wildcard = true;
 845
 846         mutex_lock(&kvm->slots_lock);
 847
 848         /* Verify that there isn't a match already */
 849         if (ioeventfd_check_collision(kvm, p)) {
 850                 ret = -EEXIST;
 851                 goto unlock_fail;
 852         }
 853
 854         kvm_iodevice_init(&p->dev, &ioeventfd_ops);
 855
 856         ret = kvm_io_bus_register_dev(kvm, bus_idx, p->addr, p->length,
 857                                       &p->dev);
 858         if (ret < 0)
 859                 goto unlock_fail;
 860
 861         kvm_get_bus(kvm, bus_idx)->ioeventfd_count++;
 862         list_add_tail(&p->list, &kvm->ioeventfds);
 863
 864         mutex_unlock(&kvm->slots_lock);
 865
 866         return 0;
 867
 868 unlock_fail:
 869         mutex_unlock(&kvm->slots_lock);
 870         kfree(p);
 871
 872 fail:
 873         eventfd_ctx_put(eventfd);
 874
 875         return ret;
 876 }
 877
 878 static int
 879 kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
 880                            struct kvm_ioeventfd *args)
 881 {
 882         struct _ioeventfd        *p;
 883         struct eventfd_ctx       *eventfd;
 884         struct kvm_io_bus        *bus;
 885         int                       ret = -ENOENT;
 886         bool                      wildcard;
 887
 888         eventfd = eventfd_ctx_fdget(args->fd);
 889         if (IS_ERR(eventfd))
 890                 return PTR_ERR(eventfd);
 891
 892         wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
 893
 894         mutex_lock(&kvm->slots_lock);
 895
 896         list_for_each_entry(p, &kvm->ioeventfds, list) {
 897                 if (p->bus_idx != bus_idx ||
 898                     p->eventfd != eventfd  ||
 899                     p->addr != args->addr  ||
 900                     p->length != args->len ||
 901                     p->wildcard != wildcard)
 902                         continue;
 903
 904                 if (!p->wildcard && p->datamatch != args->datamatch)
 905                         continue;
 906
 907                 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
 908                 bus = kvm_get_bus(kvm, bus_idx);
 909                 if (bus)
 910                         bus->ioeventfd_count--;
 911                 ret = 0;
 912                 break;
 913         }
 914
 915         mutex_unlock(&kvm->slots_lock);
 916
 917         eventfd_ctx_put(eventfd);
 918
 919         return ret;
 920 }
 921
 922 static int kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 923 {
 924         enum kvm_bus bus_idx = ioeventfd_bus_from_flags(args->flags);
 925         int ret = kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
 926
 927         if (!args->len && bus_idx == KVM_MMIO_BUS)
 928                 kvm_deassign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
 929
 930         return ret;
 931 }
 932
 933 static int
 934 kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 935 {
 936         enum kvm_bus              bus_idx;
 937         int ret;
 938
 939         bus_idx = ioeventfd_bus_from_flags(args->flags);
 940         /* must be natural-word sized, or 0 to ignore length */
 941         switch (args->len) {
 942         case 0:
 943         case 1:
 944         case 2:
 945         case 4:
 946         case 8:
 947                 break;
 948         default:
 949                 return -EINVAL;
 950         }
 951
 952         /* check for range overflow */
 953         if (args->addr + args->len < args->addr)
 954                 return -EINVAL;
 955
 956         /* check for extra flags that we don't understand */
 957         if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
 958                 return -EINVAL;
 959
 960         /* ioeventfd with no length can't be combined with DATAMATCH */
 961         if (!args->len && (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH))
 962                 return -EINVAL;
 963
 964         ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args);
 965         if (ret)
 966                 goto fail;
 967
 968         /* When length is ignored, MMIO is also put on a separate bus, for
 969          * faster lookups.
 970          */
 971         if (!args->len && bus_idx == KVM_MMIO_BUS) {
 972                 ret = kvm_assign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
 973                 if (ret < 0)
 974                         goto fast_fail;
 975         }
 976
 977         return 0;
 978
 979 fast_fail:
 980         kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
 981 fail:
 982         return ret;
 983 }
 984
 985 int
 986 kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 987 {
 988         if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
 989                 return kvm_deassign_ioeventfd(kvm, args);
 990
 991         return kvm_assign_ioeventfd(kvm, args);
 992 }
 993
 994 void
 995 kvm_eventfd_init(struct kvm *kvm)
 996 {
 997 #ifdef CONFIG_HAVE_KVM_IRQCHIP
 998         spin_lock_init(&kvm->irqfds.lock);
 999         INIT_LIST_HEAD(&kvm->irqfds.items);
1000         INIT_LIST_HEAD(&kvm->irqfds.resampler_list);
1001         mutex_init(&kvm->irqfds.resampler_lock);
1002 #endif
1003         INIT_LIST_HEAD(&kvm->ioeventfds);
1004 }