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_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 fd f; 308 struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL; 309 int ret; 310 __poll_t events; 311 int idx; 312 313 if (!kvm_arch_intc_initialized(kvm)) 314 return -EAGAIN; 315 316 if (!kvm_arch_irqfd_allowed(kvm, args)) 317 return -EINVAL; 318 319 irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL_ACCOUNT); 320 if (!irqfd) 321 return -ENOMEM; 322 323 irqfd->kvm = kvm; 324 irqfd->gsi = args->gsi; 325 INIT_LIST_HEAD(&irqfd->list); 326 INIT_WORK(&irqfd->inject, irqfd_inject); 327 INIT_WORK(&irqfd->shutdown, irqfd_shutdown); 328 seqcount_spinlock_init(&irqfd->irq_entry_sc, &kvm->irqfds.lock); 329 330 f = fdget(args->fd); 331 if (!fd_file(f)) { 332 ret = -EBADF; 333 goto out; 334 } 335 336 eventfd = eventfd_ctx_fileget(fd_file(f)); 337 if (IS_ERR(eventfd)) { 338 ret = PTR_ERR(eventfd); 339 goto fail; 340 } 341 342 irqfd->eventfd = eventfd; 343 344 if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) { 345 struct kvm_kernel_irqfd_resampler *resampler; 346 347 resamplefd = eventfd_ctx_fdget(args->resamplefd); 348 if (IS_ERR(resamplefd)) { 349 ret = PTR_ERR(resamplefd); 350 goto fail; 351 } 352 353 irqfd->resamplefd = resamplefd; 354 INIT_LIST_HEAD(&irqfd->resampler_link); 355 356 mutex_lock(&kvm->irqfds.resampler_lock); 357 358 list_for_each_entry(resampler, 359 &kvm->irqfds.resampler_list, link) { 360 if (resampler->notifier.gsi == irqfd->gsi) { 361 irqfd->resampler = resampler; 362 break; 363 } 364 } 365 366 if (!irqfd->resampler) { 367 resampler = kzalloc(sizeof(*resampler), 368 GFP_KERNEL_ACCOUNT); 369 if (!resampler) { 370 ret = -ENOMEM; 371 mutex_unlock(&kvm->irqfds.resampler_lock); 372 goto fail; 373 } 374 375 resampler->kvm = kvm; 376 INIT_LIST_HEAD(&resampler->list); 377 resampler->notifier.gsi = irqfd->gsi; 378 resampler->notifier.irq_acked = irqfd_resampler_ack; 379 INIT_LIST_HEAD(&resampler->link); 380 381 list_add_rcu(&resampler->link, &kvm->irqfds.resampler_list); 382 kvm_register_irq_ack_notifier(kvm, 383 &resampler->notifier); 384 irqfd->resampler = resampler; 385 } 386 387 list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list); 388 synchronize_srcu_expedited(&kvm->irq_srcu); 389 390 mutex_unlock(&kvm->irqfds.resampler_lock); 391 } 392 393 /* 394 * Install our own custom wake-up handling so we are notified via 395 * a callback whenever someone signals the underlying eventfd 396 */ 397 init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup); 398 init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc); 399 400 spin_lock_irq(&kvm->irqfds.lock); 401 402 ret = 0; 403 list_for_each_entry(tmp, &kvm->irqfds.items, list) { 404 if (irqfd->eventfd != tmp->eventfd) 405 continue; 406 /* This fd is used for another irq already. */ 407 ret = -EBUSY; 408 spin_unlock_irq(&kvm->irqfds.lock); 409 goto fail; 410 } 411 412 idx = srcu_read_lock(&kvm->irq_srcu); 413 irqfd_update(kvm, irqfd); 414 415 list_add_tail(&irqfd->list, &kvm->irqfds.items); 416 417 spin_unlock_irq(&kvm->irqfds.lock); 418 419 /* 420 * Check if there was an event already pending on the eventfd 421 * before we registered, and trigger it as if we didn't miss it. 422 */ 423 events = vfs_poll(fd_file(f), &irqfd->pt); 424 425 if (events & EPOLLIN) 426 schedule_work(&irqfd->inject); 427 428 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS 429 if (kvm_arch_has_irq_bypass()) { 430 irqfd->consumer.token = (void *)irqfd->eventfd; 431 irqfd->consumer.add_producer = kvm_arch_irq_bypass_add_producer; 432 irqfd->consumer.del_producer = kvm_arch_irq_bypass_del_producer; 433 irqfd->consumer.stop = kvm_arch_irq_bypass_stop; 434 irqfd->consumer.start = kvm_arch_irq_bypass_start; 435 ret = irq_bypass_register_consumer(&irqfd->consumer); 436 if (ret) 437 pr_info("irq bypass consumer (token %p) registration fails: %d\n", 438 irqfd->consumer.token, ret); 439 } 440 #endif 441 442 srcu_read_unlock(&kvm->irq_srcu, idx); 443 444 /* 445 * do not drop the file until the irqfd is fully initialized, otherwise 446 * we might race against the EPOLLHUP 447 */ 448 fdput(f); 449 return 0; 450 451 fail: 452 if (irqfd->resampler) 453 irqfd_resampler_shutdown(irqfd); 454 455 if (resamplefd && !IS_ERR(resamplefd)) 456 eventfd_ctx_put(resamplefd); 457 458 if (eventfd && !IS_ERR(eventfd)) 459 eventfd_ctx_put(eventfd); 460 461 fdput(f); 462 463 out: 464 kfree(irqfd); 465 return ret; 466 } 467 468 bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin) 469 { 470 struct kvm_irq_ack_notifier *kian; 471 int gsi, idx; 472 473 idx = srcu_read_lock(&kvm->irq_srcu); 474 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin); 475 if (gsi != -1) 476 hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list, 477 link, srcu_read_lock_held(&kvm->irq_srcu)) 478 if (kian->gsi == gsi) { 479 srcu_read_unlock(&kvm->irq_srcu, idx); 480 return true; 481 } 482 483 srcu_read_unlock(&kvm->irq_srcu, idx); 484 485 return false; 486 } 487 EXPORT_SYMBOL_GPL(kvm_irq_has_notifier); 488 489 void kvm_notify_acked_gsi(struct kvm *kvm, int gsi) 490 { 491 struct kvm_irq_ack_notifier *kian; 492 493 hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list, 494 link, srcu_read_lock_held(&kvm->irq_srcu)) 495 if (kian->gsi == gsi) 496 kian->irq_acked(kian); 497 } 498 499 void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin) 500 { 501 int gsi, idx; 502 503 trace_kvm_ack_irq(irqchip, pin); 504 505 idx = srcu_read_lock(&kvm->irq_srcu); 506 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin); 507 if (gsi != -1) 508 kvm_notify_acked_gsi(kvm, gsi); 509 srcu_read_unlock(&kvm->irq_srcu, idx); 510 } 511 512 void kvm_register_irq_ack_notifier(struct kvm *kvm, 513 struct kvm_irq_ack_notifier *kian) 514 { 515 mutex_lock(&kvm->irq_lock); 516 hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list); 517 mutex_unlock(&kvm->irq_lock); 518 kvm_arch_post_irq_ack_notifier_list_update(kvm); 519 } 520 521 void kvm_unregister_irq_ack_notifier(struct kvm *kvm, 522 struct kvm_irq_ack_notifier *kian) 523 { 524 mutex_lock(&kvm->irq_lock); 525 hlist_del_init_rcu(&kian->link); 526 mutex_unlock(&kvm->irq_lock); 527 synchronize_srcu_expedited(&kvm->irq_srcu); 528 kvm_arch_post_irq_ack_notifier_list_update(kvm); 529 } 530 531 /* 532 * shutdown any irqfd's that match fd+gsi 533 */ 534 static int 535 kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args) 536 { 537 struct kvm_kernel_irqfd *irqfd, *tmp; 538 struct eventfd_ctx *eventfd; 539 540 eventfd = eventfd_ctx_fdget(args->fd); 541 if (IS_ERR(eventfd)) 542 return PTR_ERR(eventfd); 543 544 spin_lock_irq(&kvm->irqfds.lock); 545 546 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) { 547 if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) { 548 /* 549 * This clearing of irq_entry.type is needed for when 550 * another thread calls kvm_irq_routing_update before 551 * we flush workqueue below (we synchronize with 552 * kvm_irq_routing_update using irqfds.lock). 553 */ 554 write_seqcount_begin(&irqfd->irq_entry_sc); 555 irqfd->irq_entry.type = 0; 556 write_seqcount_end(&irqfd->irq_entry_sc); 557 irqfd_deactivate(irqfd); 558 } 559 } 560 561 spin_unlock_irq(&kvm->irqfds.lock); 562 eventfd_ctx_put(eventfd); 563 564 /* 565 * Block until we know all outstanding shutdown jobs have completed 566 * so that we guarantee there will not be any more interrupts on this 567 * gsi once this deassign function returns. 568 */ 569 flush_workqueue(irqfd_cleanup_wq); 570 571 return 0; 572 } 573 574 int 575 kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args) 576 { 577 if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE)) 578 return -EINVAL; 579 580 if (args->flags & KVM_IRQFD_FLAG_DEASSIGN) 581 return kvm_irqfd_deassign(kvm, args); 582 583 return kvm_irqfd_assign(kvm, args); 584 } 585 586 /* 587 * This function is called as the kvm VM fd is being released. Shutdown all 588 * irqfds that still remain open 589 */ 590 void 591 kvm_irqfd_release(struct kvm *kvm) 592 { 593 struct kvm_kernel_irqfd *irqfd, *tmp; 594 595 spin_lock_irq(&kvm->irqfds.lock); 596 597 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) 598 irqfd_deactivate(irqfd); 599 600 spin_unlock_irq(&kvm->irqfds.lock); 601 602 /* 603 * Block until we know all outstanding shutdown jobs have completed 604 * since we do not take a kvm* reference. 605 */ 606 flush_workqueue(irqfd_cleanup_wq); 607 608 } 609 610 /* 611 * Take note of a change in irq routing. 612 * Caller must invoke synchronize_srcu_expedited(&kvm->irq_srcu) afterwards. 613 */ 614 void kvm_irq_routing_update(struct kvm *kvm) 615 { 616 struct kvm_kernel_irqfd *irqfd; 617 618 spin_lock_irq(&kvm->irqfds.lock); 619 620 list_for_each_entry(irqfd, &kvm->irqfds.items, list) { 621 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS 622 /* Under irqfds.lock, so can read irq_entry safely */ 623 struct kvm_kernel_irq_routing_entry old = irqfd->irq_entry; 624 #endif 625 626 irqfd_update(kvm, irqfd); 627 628 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS 629 if (irqfd->producer && 630 kvm_arch_irqfd_route_changed(&old, &irqfd->irq_entry)) { 631 int ret = kvm_arch_update_irqfd_routing( 632 irqfd->kvm, irqfd->producer->irq, 633 irqfd->gsi, 1); 634 WARN_ON(ret); 635 } 636 #endif 637 } 638 639 spin_unlock_irq(&kvm->irqfds.lock); 640 } 641 642 bool kvm_notify_irqfd_resampler(struct kvm *kvm, 643 unsigned int irqchip, 644 unsigned int pin) 645 { 646 struct kvm_kernel_irqfd_resampler *resampler; 647 int gsi, idx; 648 649 idx = srcu_read_lock(&kvm->irq_srcu); 650 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin); 651 if (gsi != -1) { 652 list_for_each_entry_srcu(resampler, 653 &kvm->irqfds.resampler_list, link, 654 srcu_read_lock_held(&kvm->irq_srcu)) { 655 if (resampler->notifier.gsi == gsi) { 656 irqfd_resampler_notify(resampler); 657 srcu_read_unlock(&kvm->irq_srcu, idx); 658 return true; 659 } 660 } 661 } 662 srcu_read_unlock(&kvm->irq_srcu, idx); 663 664 return false; 665 } 666 667 /* 668 * create a host-wide workqueue for issuing deferred shutdown requests 669 * aggregated from all vm* instances. We need our own isolated 670 * queue to ease flushing work items when a VM exits. 671 */ 672 int kvm_irqfd_init(void) 673 { 674 irqfd_cleanup_wq = alloc_workqueue("kvm-irqfd-cleanup", 0, 0); 675 if (!irqfd_cleanup_wq) 676 return -ENOMEM; 677 678 return 0; 679 } 680 681 void kvm_irqfd_exit(void) 682 { 683 destroy_workqueue(irqfd_cleanup_wq); 684 } 685 #endif 686 687 /* 688 * -------------------------------------------------------------------- 689 * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal. 690 * 691 * userspace can register a PIO/MMIO address with an eventfd for receiving 692 * notification when the memory has been touched. 693 * -------------------------------------------------------------------- 694 */ 695 696 struct _ioeventfd { 697 struct list_head list; 698 u64 addr; 699 int length; 700 struct eventfd_ctx *eventfd; 701 u64 datamatch; 702 struct kvm_io_device dev; 703 u8 bus_idx; 704 bool wildcard; 705 }; 706 707 static inline struct _ioeventfd * 708 to_ioeventfd(struct kvm_io_device *dev) 709 { 710 return container_of(dev, struct _ioeventfd, dev); 711 } 712 713 static void 714 ioeventfd_release(struct _ioeventfd *p) 715 { 716 eventfd_ctx_put(p->eventfd); 717 list_del(&p->list); 718 kfree(p); 719 } 720 721 static bool 722 ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val) 723 { 724 u64 _val; 725 726 if (addr != p->addr) 727 /* address must be precise for a hit */ 728 return false; 729 730 if (!p->length) 731 /* length = 0 means only look at the address, so always a hit */ 732 return true; 733 734 if (len != p->length) 735 /* address-range must be precise for a hit */ 736 return false; 737 738 if (p->wildcard) 739 /* all else equal, wildcard is always a hit */ 740 return true; 741 742 /* otherwise, we have to actually compare the data */ 743 744 BUG_ON(!IS_ALIGNED((unsigned long)val, len)); 745 746 switch (len) { 747 case 1: 748 _val = *(u8 *)val; 749 break; 750 case 2: 751 _val = *(u16 *)val; 752 break; 753 case 4: 754 _val = *(u32 *)val; 755 break; 756 case 8: 757 _val = *(u64 *)val; 758 break; 759 default: 760 return false; 761 } 762 763 return _val == p->datamatch; 764 } 765 766 /* MMIO/PIO writes trigger an event if the addr/val match */ 767 static int 768 ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr, 769 int len, const void *val) 770 { 771 struct _ioeventfd *p = to_ioeventfd(this); 772 773 if (!ioeventfd_in_range(p, addr, len, val)) 774 return -EOPNOTSUPP; 775 776 eventfd_signal(p->eventfd); 777 return 0; 778 } 779 780 /* 781 * This function is called as KVM is completely shutting down. We do not 782 * need to worry about locking just nuke anything we have as quickly as possible 783 */ 784 static void 785 ioeventfd_destructor(struct kvm_io_device *this) 786 { 787 struct _ioeventfd *p = to_ioeventfd(this); 788 789 ioeventfd_release(p); 790 } 791 792 static const struct kvm_io_device_ops ioeventfd_ops = { 793 .write = ioeventfd_write, 794 .destructor = ioeventfd_destructor, 795 }; 796 797 /* assumes kvm->slots_lock held */ 798 static bool 799 ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p) 800 { 801 struct _ioeventfd *_p; 802 803 list_for_each_entry(_p, &kvm->ioeventfds, list) 804 if (_p->bus_idx == p->bus_idx && 805 _p->addr == p->addr && 806 (!_p->length || !p->length || 807 (_p->length == p->length && 808 (_p->wildcard || p->wildcard || 809 _p->datamatch == p->datamatch)))) 810 return true; 811 812 return false; 813 } 814 815 static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags) 816 { 817 if (flags & KVM_IOEVENTFD_FLAG_PIO) 818 return KVM_PIO_BUS; 819 if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY) 820 return KVM_VIRTIO_CCW_NOTIFY_BUS; 821 return KVM_MMIO_BUS; 822 } 823 824 static int kvm_assign_ioeventfd_idx(struct kvm *kvm, 825 enum kvm_bus bus_idx, 826 struct kvm_ioeventfd *args) 827 { 828 829 struct eventfd_ctx *eventfd; 830 struct _ioeventfd *p; 831 int ret; 832 833 eventfd = eventfd_ctx_fdget(args->fd); 834 if (IS_ERR(eventfd)) 835 return PTR_ERR(eventfd); 836 837 p = kzalloc(sizeof(*p), GFP_KERNEL_ACCOUNT); 838 if (!p) { 839 ret = -ENOMEM; 840 goto fail; 841 } 842 843 INIT_LIST_HEAD(&p->list); 844 p->addr = args->addr; 845 p->bus_idx = bus_idx; 846 p->length = args->len; 847 p->eventfd = eventfd; 848 849 /* The datamatch feature is optional, otherwise this is a wildcard */ 850 if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH) 851 p->datamatch = args->datamatch; 852 else 853 p->wildcard = true; 854 855 mutex_lock(&kvm->slots_lock); 856 857 /* Verify that there isn't a match already */ 858 if (ioeventfd_check_collision(kvm, p)) { 859 ret = -EEXIST; 860 goto unlock_fail; 861 } 862 863 kvm_iodevice_init(&p->dev, &ioeventfd_ops); 864 865 ret = kvm_io_bus_register_dev(kvm, bus_idx, p->addr, p->length, 866 &p->dev); 867 if (ret < 0) 868 goto unlock_fail; 869 870 kvm_get_bus(kvm, bus_idx)->ioeventfd_count++; 871 list_add_tail(&p->list, &kvm->ioeventfds); 872 873 mutex_unlock(&kvm->slots_lock); 874 875 return 0; 876 877 unlock_fail: 878 mutex_unlock(&kvm->slots_lock); 879 kfree(p); 880 881 fail: 882 eventfd_ctx_put(eventfd); 883 884 return ret; 885 } 886 887 static int 888 kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx, 889 struct kvm_ioeventfd *args) 890 { 891 struct _ioeventfd *p; 892 struct eventfd_ctx *eventfd; 893 struct kvm_io_bus *bus; 894 int ret = -ENOENT; 895 bool wildcard; 896 897 eventfd = eventfd_ctx_fdget(args->fd); 898 if (IS_ERR(eventfd)) 899 return PTR_ERR(eventfd); 900 901 wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH); 902 903 mutex_lock(&kvm->slots_lock); 904 905 list_for_each_entry(p, &kvm->ioeventfds, list) { 906 if (p->bus_idx != bus_idx || 907 p->eventfd != eventfd || 908 p->addr != args->addr || 909 p->length != args->len || 910 p->wildcard != wildcard) 911 continue; 912 913 if (!p->wildcard && p->datamatch != args->datamatch) 914 continue; 915 916 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev); 917 bus = kvm_get_bus(kvm, bus_idx); 918 if (bus) 919 bus->ioeventfd_count--; 920 ret = 0; 921 break; 922 } 923 924 mutex_unlock(&kvm->slots_lock); 925 926 eventfd_ctx_put(eventfd); 927 928 return ret; 929 } 930 931 static int kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args) 932 { 933 enum kvm_bus bus_idx = ioeventfd_bus_from_flags(args->flags); 934 int ret = kvm_deassign_ioeventfd_idx(kvm, bus_idx, args); 935 936 if (!args->len && bus_idx == KVM_MMIO_BUS) 937 kvm_deassign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args); 938 939 return ret; 940 } 941 942 static int 943 kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args) 944 { 945 enum kvm_bus bus_idx; 946 int ret; 947 948 bus_idx = ioeventfd_bus_from_flags(args->flags); 949 /* must be natural-word sized, or 0 to ignore length */ 950 switch (args->len) { 951 case 0: 952 case 1: 953 case 2: 954 case 4: 955 case 8: 956 break; 957 default: 958 return -EINVAL; 959 } 960 961 /* check for range overflow */ 962 if (args->addr + args->len < args->addr) 963 return -EINVAL; 964 965 /* check for extra flags that we don't understand */ 966 if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK) 967 return -EINVAL; 968 969 /* ioeventfd with no length can't be combined with DATAMATCH */ 970 if (!args->len && (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)) 971 return -EINVAL; 972 973 ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args); 974 if (ret) 975 goto fail; 976 977 /* When length is ignored, MMIO is also put on a separate bus, for 978 * faster lookups. 979 */ 980 if (!args->len && bus_idx == KVM_MMIO_BUS) { 981 ret = kvm_assign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args); 982 if (ret < 0) 983 goto fast_fail; 984 } 985 986 return 0; 987 988 fast_fail: 989 kvm_deassign_ioeventfd_idx(kvm, bus_idx, args); 990 fail: 991 return ret; 992 } 993 994 int 995 kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args) 996 { 997 if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN) 998 return kvm_deassign_ioeventfd(kvm, args); 999 1000 return kvm_assign_ioeventfd(kvm, args); 1001 } 1002 1003 void 1004 kvm_eventfd_init(struct kvm *kvm) 1005 { 1006 #ifdef CONFIG_HAVE_KVM_IRQCHIP 1007 spin_lock_init(&kvm->irqfds.lock); 1008 INIT_LIST_HEAD(&kvm->irqfds.items); 1009 INIT_LIST_HEAD(&kvm->irqfds.resampler_list); 1010 mutex_init(&kvm->irqfds.resampler_lock); 1011 #endif 1012 INIT_LIST_HEAD(&kvm->ioeventfds); 1013 } 1014