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