1014 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * kvm eventfd support - use eventfd objects to signal various KVM events4 *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_IRQCHIP32 33static struct workqueue_struct *irqfd_cleanup_wq;34 35bool __attribute__((weak))36kvm_arch_irqfd_allowed(struct kvm *kvm, struct kvm_irqfd *args)37{38 return true;39}40 41static void42irqfd_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 } else54 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,55 irqfd->gsi, 1, false);56}57 58static 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 once69 * then notify all of the resampler irqfds using this GSI. We can't70 * do multiple de-asserts or we risk racing with incoming re-asserts.71 */72static void73irqfd_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 91static void92irqfd_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 called106 * 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 */121static void122irqfd_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 prevent134 * 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 block140 * until all previously outstanding events have completed141 */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 resources151 */152#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS153 irq_bypass_unregister_consumer(&irqfd->consumer);154#endif155 eventfd_ctx_put(irqfd->eventfd);156 kfree(irqfd);157}158 159 160/* assumes kvm->irqfds.lock is held */161static bool162irqfd_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 removal169 *170 * assumes kvm->irqfds.lock is held171 */172static void173irqfd_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 182int __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 disabled193 */194static int195irqfd_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 before232 * we could acquire the irqfds.lock since the item is233 * deactivated from the KVM side before it is unhooked from234 * the wait-queue. If it is already deactivated, we can235 * simply return knowing the other side will cleanup for us.236 * We cannot race against the irqfd going away since the237 * other side is required to acquire wqh->lock, which we hold238 */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 248static void249irqfd_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 */258static 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 else272 irqfd->irq_entry.type = 0;273 274 write_seqcount_end(&irqfd->irq_entry_sc);275}276 277#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS278void __attribute__((weak)) kvm_arch_irq_bypass_stop(279 struct irq_bypass_consumer *cons)280{281}282 283void __attribute__((weak)) kvm_arch_irq_bypass_start(284 struct irq_bypass_consumer *cons)285{286}287 288int __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 295bool __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#endif302 303static int304kvm_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 via395 * a callback whenever someone signals the underlying eventfd396 */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 eventfd421 * 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_BYPASS429 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#endif441 442 srcu_read_unlock(&kvm->irq_srcu, idx);443 444 /*445 * do not drop the file until the irqfd is fully initialized, otherwise446 * we might race against the EPOLLHUP447 */448 fdput(f);449 return 0;450 451fail: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 463out:464 kfree(irqfd);465 return ret;466}467 468bool 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}487EXPORT_SYMBOL_GPL(kvm_irq_has_notifier);488 489void 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 499void 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 512void 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 521void 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+gsi533 */534static int535kvm_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 when550 * another thread calls kvm_irq_routing_update before551 * we flush workqueue below (we synchronize with552 * 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 completed566 * so that we guarantee there will not be any more interrupts on this567 * gsi once this deassign function returns.568 */569 flush_workqueue(irqfd_cleanup_wq);570 571 return 0;572}573 574int575kvm_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 all588 * irqfds that still remain open589 */590void591kvm_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 completed604 * 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 */614void 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_BYPASS622 /* Under irqfds.lock, so can read irq_entry safely */623 struct kvm_kernel_irq_routing_entry old = irqfd->irq_entry;624#endif625 626 irqfd_update(kvm, irqfd);627 628#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS629 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#endif637 }638 639 spin_unlock_irq(&kvm->irqfds.lock);640}641 642bool 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 requests669 * aggregated from all vm* instances. We need our own isolated670 * queue to ease flushing work items when a VM exits.671 */672int 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 681void kvm_irqfd_exit(void)682{683 destroy_workqueue(irqfd_cleanup_wq);684}685#endif686 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 receiving692 * notification when the memory has been touched.693 * --------------------------------------------------------------------694 */695 696struct _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 707static inline struct _ioeventfd *708to_ioeventfd(struct kvm_io_device *dev)709{710 return container_of(dev, struct _ioeventfd, dev);711}712 713static void714ioeventfd_release(struct _ioeventfd *p)715{716 eventfd_ctx_put(p->eventfd);717 list_del(&p->list);718 kfree(p);719}720 721static bool722ioeventfd_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 */767static int768ioeventfd_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 not782 * need to worry about locking just nuke anything we have as quickly as possible783 */784static void785ioeventfd_destructor(struct kvm_io_device *this)786{787 struct _ioeventfd *p = to_ioeventfd(this);788 789 ioeventfd_release(p);790}791 792static const struct kvm_io_device_ops ioeventfd_ops = {793 .write = ioeventfd_write,794 .destructor = ioeventfd_destructor,795};796 797/* assumes kvm->slots_lock held */798static bool799ioeventfd_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 815static 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 824static 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 else853 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 877unlock_fail:878 mutex_unlock(&kvm->slots_lock);879 kfree(p);880 881fail:882 eventfd_ctx_put(eventfd);883 884 return ret;885}886 887static int888kvm_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 931static 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 942static int943kvm_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, for978 * 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 988fast_fail:989 kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);990fail:991 return ret;992}993 994int995kvm_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 1003void1004kvm_eventfd_init(struct kvm *kvm)1005{1006#ifdef CONFIG_HAVE_KVM_IRQCHIP1007 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#endif1012 INIT_LIST_HEAD(&kvm->ioeventfds);1013}1014