1/*
2 * kvm eventfd support - use eventfd objects to signal various KVM events
3 *
4 * Copyright 2009 Novell.  All Rights Reserved.
5 * Copyright 2010 Red Hat, Inc. and/or its affiliates.
6 *
7 * Author:
8 *	Gregory Haskins <ghaskins@novell.com>
9 *
10 * This file is free software; you can redistribute it and/or modify
11 * it under the terms of version 2 of the GNU General Public License
12 * as published by the Free Software Foundation.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software Foundation,
21 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
22 */
23
24#include <linux/kvm_host.h>
25#include <linux/kvm.h>
26#include <linux/kvm_irqfd.h>
27#include <linux/workqueue.h>
28#include <linux/syscalls.h>
29#include <linux/wait.h>
30#include <linux/poll.h>
31#include <linux/file.h>
32#include <linux/list.h>
33#include <linux/eventfd.h>
34#include <linux/kernel.h>
35#include <linux/srcu.h>
36#include <linux/slab.h>
37#include <linux/seqlock.h>
38#include <linux/irqbypass.h>
39#include <trace/events/kvm.h>
40
41#include <kvm/iodev.h>
42
43#ifdef CONFIG_HAVE_KVM_IRQFD
44
45static struct workqueue_struct *irqfd_cleanup_wq;
46
47static void
48irqfd_inject(struct work_struct *work)
49{
50	struct kvm_kernel_irqfd *irqfd =
51		container_of(work, struct kvm_kernel_irqfd, inject);
52	struct kvm *kvm = irqfd->kvm;
53
54	if (!irqfd->resampler) {
55		kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1,
56				false);
57		kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0,
58				false);
59	} else
60		kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
61			    irqfd->gsi, 1, false);
62}
63
64/*
65 * Since resampler irqfds share an IRQ source ID, we de-assert once
66 * then notify all of the resampler irqfds using this GSI.  We can't
67 * do multiple de-asserts or we risk racing with incoming re-asserts.
68 */
69static void
70irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian)
71{
72	struct kvm_kernel_irqfd_resampler *resampler;
73	struct kvm *kvm;
74	struct kvm_kernel_irqfd *irqfd;
75	int idx;
76
77	resampler = container_of(kian,
78			struct kvm_kernel_irqfd_resampler, notifier);
79	kvm = resampler->kvm;
80
81	kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
82		    resampler->notifier.gsi, 0, false);
83
84	idx = srcu_read_lock(&kvm->irq_srcu);
85
86	list_for_each_entry_rcu(irqfd, &resampler->list, resampler_link)
87		eventfd_signal(irqfd->resamplefd, 1);
88
89	srcu_read_unlock(&kvm->irq_srcu, idx);
90}
91
92static void
93irqfd_resampler_shutdown(struct kvm_kernel_irqfd *irqfd)
94{
95	struct kvm_kernel_irqfd_resampler *resampler = irqfd->resampler;
96	struct kvm *kvm = resampler->kvm;
97
98	mutex_lock(&kvm->irqfds.resampler_lock);
99
100	list_del_rcu(&irqfd->resampler_link);
101	synchronize_srcu(&kvm->irq_srcu);
102
103	if (list_empty(&resampler->list)) {
104		list_del(&resampler->link);
105		kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier);
106		kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
107			    resampler->notifier.gsi, 0, false);
108		kfree(resampler);
109	}
110
111	mutex_unlock(&kvm->irqfds.resampler_lock);
112}
113
114/*
115 * Race-free decouple logic (ordering is critical)
116 */
117static void
118irqfd_shutdown(struct work_struct *work)
119{
120	struct kvm_kernel_irqfd *irqfd =
121		container_of(work, struct kvm_kernel_irqfd, shutdown);
122	u64 cnt;
123
124	/*
125	 * Synchronize with the wait-queue and unhook ourselves to prevent
126	 * further events.
127	 */
128	eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
129
130	/*
131	 * We know no new events will be scheduled at this point, so block
132	 * until all previously outstanding events have completed
133	 */
134	flush_work(&irqfd->inject);
135
136	if (irqfd->resampler) {
137		irqfd_resampler_shutdown(irqfd);
138		eventfd_ctx_put(irqfd->resamplefd);
139	}
140
141	/*
142	 * It is now safe to release the object's resources
143	 */
144#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
145	irq_bypass_unregister_consumer(&irqfd->consumer);
146#endif
147	eventfd_ctx_put(irqfd->eventfd);
148	kfree(irqfd);
149}
150
151
152/* assumes kvm->irqfds.lock is held */
153static bool
154irqfd_is_active(struct kvm_kernel_irqfd *irqfd)
155{
156	return list_empty(&irqfd->list) ? false : true;
157}
158
159/*
160 * Mark the irqfd as inactive and schedule it for removal
161 *
162 * assumes kvm->irqfds.lock is held
163 */
164static void
165irqfd_deactivate(struct kvm_kernel_irqfd *irqfd)
166{
167	BUG_ON(!irqfd_is_active(irqfd));
168
169	list_del_init(&irqfd->list);
170
171	queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
172}
173
174int __attribute__((weak)) kvm_arch_set_irq_inatomic(
175				struct kvm_kernel_irq_routing_entry *irq,
176				struct kvm *kvm, int irq_source_id,
177				int level,
178				bool line_status)
179{
180	return -EWOULDBLOCK;
181}
182
183/*
184 * Called with wqh->lock held and interrupts disabled
185 */
186static int
187irqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key)
188{
189	struct kvm_kernel_irqfd *irqfd =
190		container_of(wait, struct kvm_kernel_irqfd, wait);
191	unsigned long flags = (unsigned long)key;
192	struct kvm_kernel_irq_routing_entry irq;
193	struct kvm *kvm = irqfd->kvm;
194	unsigned seq;
195	int idx;
196
197	if (flags & POLLIN) {
198		idx = srcu_read_lock(&kvm->irq_srcu);
199		do {
200			seq = read_seqcount_begin(&irqfd->irq_entry_sc);
201			irq = irqfd->irq_entry;
202		} while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
203		/* An event has been signaled, inject an interrupt */
204		if (kvm_arch_set_irq_inatomic(&irq, kvm,
205					      KVM_USERSPACE_IRQ_SOURCE_ID, 1,
206					      false) == -EWOULDBLOCK)
207			schedule_work(&irqfd->inject);
208		srcu_read_unlock(&kvm->irq_srcu, idx);
209	}
210
211	if (flags & POLLHUP) {
212		/* The eventfd is closing, detach from KVM */
213		unsigned long flags;
214
215		spin_lock_irqsave(&kvm->irqfds.lock, flags);
216
217		/*
218		 * We must check if someone deactivated the irqfd before
219		 * we could acquire the irqfds.lock since the item is
220		 * deactivated from the KVM side before it is unhooked from
221		 * the wait-queue.  If it is already deactivated, we can
222		 * simply return knowing the other side will cleanup for us.
223		 * We cannot race against the irqfd going away since the
224		 * other side is required to acquire wqh->lock, which we hold
225		 */
226		if (irqfd_is_active(irqfd))
227			irqfd_deactivate(irqfd);
228
229		spin_unlock_irqrestore(&kvm->irqfds.lock, flags);
230	}
231
232	return 0;
233}
234
235static void
236irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
237			poll_table *pt)
238{
239	struct kvm_kernel_irqfd *irqfd =
240		container_of(pt, struct kvm_kernel_irqfd, pt);
241	add_wait_queue(wqh, &irqfd->wait);
242}
243
244/* Must be called under irqfds.lock */
245static void irqfd_update(struct kvm *kvm, struct kvm_kernel_irqfd *irqfd)
246{
247	struct kvm_kernel_irq_routing_entry *e;
248	struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
249	int n_entries;
250
251	n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);
252
253	write_seqcount_begin(&irqfd->irq_entry_sc);
254
255	e = entries;
256	if (n_entries == 1)
257		irqfd->irq_entry = *e;
258	else
259		irqfd->irq_entry.type = 0;
260
261	write_seqcount_end(&irqfd->irq_entry_sc);
262}
263
264#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
265void __attribute__((weak)) kvm_arch_irq_bypass_stop(
266				struct irq_bypass_consumer *cons)
267{
268}
269
270void __attribute__((weak)) kvm_arch_irq_bypass_start(
271				struct irq_bypass_consumer *cons)
272{
273}
274
275int  __attribute__((weak)) kvm_arch_update_irqfd_routing(
276				struct kvm *kvm, unsigned int host_irq,
277				uint32_t guest_irq, bool set)
278{
279	return 0;
280}
281#endif
282
283static int
284kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
285{
286	struct kvm_kernel_irqfd *irqfd, *tmp;
287	struct fd f;
288	struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
289	int ret;
290	unsigned int events;
291	int idx;
292
293	if (!kvm_arch_intc_initialized(kvm))
294		return -EAGAIN;
295
296	irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
297	if (!irqfd)
298		return -ENOMEM;
299
300	irqfd->kvm = kvm;
301	irqfd->gsi = args->gsi;
302	INIT_LIST_HEAD(&irqfd->list);
303	INIT_WORK(&irqfd->inject, irqfd_inject);
304	INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
305	seqcount_init(&irqfd->irq_entry_sc);
306
307	f = fdget(args->fd);
308	if (!f.file) {
309		ret = -EBADF;
310		goto out;
311	}
312
313	eventfd = eventfd_ctx_fileget(f.file);
314	if (IS_ERR(eventfd)) {
315		ret = PTR_ERR(eventfd);
316		goto fail;
317	}
318
319	irqfd->eventfd = eventfd;
320
321	if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) {
322		struct kvm_kernel_irqfd_resampler *resampler;
323
324		resamplefd = eventfd_ctx_fdget(args->resamplefd);
325		if (IS_ERR(resamplefd)) {
326			ret = PTR_ERR(resamplefd);
327			goto fail;
328		}
329
330		irqfd->resamplefd = resamplefd;
331		INIT_LIST_HEAD(&irqfd->resampler_link);
332
333		mutex_lock(&kvm->irqfds.resampler_lock);
334
335		list_for_each_entry(resampler,
336				    &kvm->irqfds.resampler_list, link) {
337			if (resampler->notifier.gsi == irqfd->gsi) {
338				irqfd->resampler = resampler;
339				break;
340			}
341		}
342
343		if (!irqfd->resampler) {
344			resampler = kzalloc(sizeof(*resampler), GFP_KERNEL);
345			if (!resampler) {
346				ret = -ENOMEM;
347				mutex_unlock(&kvm->irqfds.resampler_lock);
348				goto fail;
349			}
350
351			resampler->kvm = kvm;
352			INIT_LIST_HEAD(&resampler->list);
353			resampler->notifier.gsi = irqfd->gsi;
354			resampler->notifier.irq_acked = irqfd_resampler_ack;
355			INIT_LIST_HEAD(&resampler->link);
356
357			list_add(&resampler->link, &kvm->irqfds.resampler_list);
358			kvm_register_irq_ack_notifier(kvm,
359						      &resampler->notifier);
360			irqfd->resampler = resampler;
361		}
362
363		list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list);
364		synchronize_srcu(&kvm->irq_srcu);
365
366		mutex_unlock(&kvm->irqfds.resampler_lock);
367	}
368
369	/*
370	 * Install our own custom wake-up handling so we are notified via
371	 * a callback whenever someone signals the underlying eventfd
372	 */
373	init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
374	init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
375
376	spin_lock_irq(&kvm->irqfds.lock);
377
378	ret = 0;
379	list_for_each_entry(tmp, &kvm->irqfds.items, list) {
380		if (irqfd->eventfd != tmp->eventfd)
381			continue;
382		/* This fd is used for another irq already. */
383		ret = -EBUSY;
384		spin_unlock_irq(&kvm->irqfds.lock);
385		goto fail;
386	}
387
388	idx = srcu_read_lock(&kvm->irq_srcu);
389	irqfd_update(kvm, irqfd);
390	srcu_read_unlock(&kvm->irq_srcu, idx);
391
392	list_add_tail(&irqfd->list, &kvm->irqfds.items);
393
394	spin_unlock_irq(&kvm->irqfds.lock);
395
396	/*
397	 * Check if there was an event already pending on the eventfd
398	 * before we registered, and trigger it as if we didn't miss it.
399	 */
400	events = f.file->f_op->poll(f.file, &irqfd->pt);
401
402	if (events & POLLIN)
403		schedule_work(&irqfd->inject);
404
405	/*
406	 * do not drop the file until the irqfd is fully initialized, otherwise
407	 * we might race against the POLLHUP
408	 */
409	fdput(f);
410#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
411	irqfd->consumer.token = (void *)irqfd->eventfd;
412	irqfd->consumer.add_producer = kvm_arch_irq_bypass_add_producer;
413	irqfd->consumer.del_producer = kvm_arch_irq_bypass_del_producer;
414	irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
415	irqfd->consumer.start = kvm_arch_irq_bypass_start;
416	ret = irq_bypass_register_consumer(&irqfd->consumer);
417	if (ret)
418		pr_info("irq bypass consumer (token %p) registration fails: %d\n",
419				irqfd->consumer.token, ret);
420#endif
421
422	return 0;
423
424fail:
425	if (irqfd->resampler)
426		irqfd_resampler_shutdown(irqfd);
427
428	if (resamplefd && !IS_ERR(resamplefd))
429		eventfd_ctx_put(resamplefd);
430
431	if (eventfd && !IS_ERR(eventfd))
432		eventfd_ctx_put(eventfd);
433
434	fdput(f);
435
436out:
437	kfree(irqfd);
438	return ret;
439}
440
441bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin)
442{
443	struct kvm_irq_ack_notifier *kian;
444	int gsi, idx;
445
446	idx = srcu_read_lock(&kvm->irq_srcu);
447	gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
448	if (gsi != -1)
449		hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list,
450					 link)
451			if (kian->gsi == gsi) {
452				srcu_read_unlock(&kvm->irq_srcu, idx);
453				return true;
454			}
455
456	srcu_read_unlock(&kvm->irq_srcu, idx);
457
458	return false;
459}
460EXPORT_SYMBOL_GPL(kvm_irq_has_notifier);
461
462void kvm_notify_acked_gsi(struct kvm *kvm, int gsi)
463{
464	struct kvm_irq_ack_notifier *kian;
465
466	hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list,
467				 link)
468		if (kian->gsi == gsi)
469			kian->irq_acked(kian);
470}
471
472void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
473{
474	int gsi, idx;
475
476	trace_kvm_ack_irq(irqchip, pin);
477
478	idx = srcu_read_lock(&kvm->irq_srcu);
479	gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
480	if (gsi != -1)
481		kvm_notify_acked_gsi(kvm, gsi);
482	srcu_read_unlock(&kvm->irq_srcu, idx);
483}
484
485void kvm_register_irq_ack_notifier(struct kvm *kvm,
486				   struct kvm_irq_ack_notifier *kian)
487{
488	mutex_lock(&kvm->irq_lock);
489	hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list);
490	mutex_unlock(&kvm->irq_lock);
491	kvm_vcpu_request_scan_ioapic(kvm);
492}
493
494void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
495				    struct kvm_irq_ack_notifier *kian)
496{
497	mutex_lock(&kvm->irq_lock);
498	hlist_del_init_rcu(&kian->link);
499	mutex_unlock(&kvm->irq_lock);
500	synchronize_srcu(&kvm->irq_srcu);
501	kvm_vcpu_request_scan_ioapic(kvm);
502}
503#endif
504
505void
506kvm_eventfd_init(struct kvm *kvm)
507{
508#ifdef CONFIG_HAVE_KVM_IRQFD
509	spin_lock_init(&kvm->irqfds.lock);
510	INIT_LIST_HEAD(&kvm->irqfds.items);
511	INIT_LIST_HEAD(&kvm->irqfds.resampler_list);
512	mutex_init(&kvm->irqfds.resampler_lock);
513#endif
514	INIT_LIST_HEAD(&kvm->ioeventfds);
515}
516
517#ifdef CONFIG_HAVE_KVM_IRQFD
518/*
519 * shutdown any irqfd's that match fd+gsi
520 */
521static int
522kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
523{
524	struct kvm_kernel_irqfd *irqfd, *tmp;
525	struct eventfd_ctx *eventfd;
526
527	eventfd = eventfd_ctx_fdget(args->fd);
528	if (IS_ERR(eventfd))
529		return PTR_ERR(eventfd);
530
531	spin_lock_irq(&kvm->irqfds.lock);
532
533	list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
534		if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) {
535			/*
536			 * This clearing of irq_entry.type is needed for when
537			 * another thread calls kvm_irq_routing_update before
538			 * we flush workqueue below (we synchronize with
539			 * kvm_irq_routing_update using irqfds.lock).
540			 */
541			write_seqcount_begin(&irqfd->irq_entry_sc);
542			irqfd->irq_entry.type = 0;
543			write_seqcount_end(&irqfd->irq_entry_sc);
544			irqfd_deactivate(irqfd);
545		}
546	}
547
548	spin_unlock_irq(&kvm->irqfds.lock);
549	eventfd_ctx_put(eventfd);
550
551	/*
552	 * Block until we know all outstanding shutdown jobs have completed
553	 * so that we guarantee there will not be any more interrupts on this
554	 * gsi once this deassign function returns.
555	 */
556	flush_workqueue(irqfd_cleanup_wq);
557
558	return 0;
559}
560
561int
562kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
563{
564	if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE))
565		return -EINVAL;
566
567	if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
568		return kvm_irqfd_deassign(kvm, args);
569
570	return kvm_irqfd_assign(kvm, args);
571}
572
573/*
574 * This function is called as the kvm VM fd is being released. Shutdown all
575 * irqfds that still remain open
576 */
577void
578kvm_irqfd_release(struct kvm *kvm)
579{
580	struct kvm_kernel_irqfd *irqfd, *tmp;
581
582	spin_lock_irq(&kvm->irqfds.lock);
583
584	list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
585		irqfd_deactivate(irqfd);
586
587	spin_unlock_irq(&kvm->irqfds.lock);
588
589	/*
590	 * Block until we know all outstanding shutdown jobs have completed
591	 * since we do not take a kvm* reference.
592	 */
593	flush_workqueue(irqfd_cleanup_wq);
594
595}
596
597/*
598 * Take note of a change in irq routing.
599 * Caller must invoke synchronize_srcu(&kvm->irq_srcu) afterwards.
600 */
601void kvm_irq_routing_update(struct kvm *kvm)
602{
603	struct kvm_kernel_irqfd *irqfd;
604
605	spin_lock_irq(&kvm->irqfds.lock);
606
607	list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
608		irqfd_update(kvm, irqfd);
609
610#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
611		if (irqfd->producer) {
612			int ret = kvm_arch_update_irqfd_routing(
613					irqfd->kvm, irqfd->producer->irq,
614					irqfd->gsi, 1);
615			WARN_ON(ret);
616		}
617#endif
618	}
619
620	spin_unlock_irq(&kvm->irqfds.lock);
621}
622
623/*
624 * create a host-wide workqueue for issuing deferred shutdown requests
625 * aggregated from all vm* instances. We need our own isolated single-thread
626 * queue to prevent deadlock against flushing the normal work-queue.
627 */
628int kvm_irqfd_init(void)
629{
630	irqfd_cleanup_wq = create_singlethread_workqueue("kvm-irqfd-cleanup");
631	if (!irqfd_cleanup_wq)
632		return -ENOMEM;
633
634	return 0;
635}
636
637void kvm_irqfd_exit(void)
638{
639	destroy_workqueue(irqfd_cleanup_wq);
640}
641#endif
642
643/*
644 * --------------------------------------------------------------------
645 * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
646 *
647 * userspace can register a PIO/MMIO address with an eventfd for receiving
648 * notification when the memory has been touched.
649 * --------------------------------------------------------------------
650 */
651
652struct _ioeventfd {
653	struct list_head     list;
654	u64                  addr;
655	int                  length;
656	struct eventfd_ctx  *eventfd;
657	u64                  datamatch;
658	struct kvm_io_device dev;
659	u8                   bus_idx;
660	bool                 wildcard;
661};
662
663static inline struct _ioeventfd *
664to_ioeventfd(struct kvm_io_device *dev)
665{
666	return container_of(dev, struct _ioeventfd, dev);
667}
668
669static void
670ioeventfd_release(struct _ioeventfd *p)
671{
672	eventfd_ctx_put(p->eventfd);
673	list_del(&p->list);
674	kfree(p);
675}
676
677static bool
678ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
679{
680	u64 _val;
681
682	if (addr != p->addr)
683		/* address must be precise for a hit */
684		return false;
685
686	if (!p->length)
687		/* length = 0 means only look at the address, so always a hit */
688		return true;
689
690	if (len != p->length)
691		/* address-range must be precise for a hit */
692		return false;
693
694	if (p->wildcard)
695		/* all else equal, wildcard is always a hit */
696		return true;
697
698	/* otherwise, we have to actually compare the data */
699
700	BUG_ON(!IS_ALIGNED((unsigned long)val, len));
701
702	switch (len) {
703	case 1:
704		_val = *(u8 *)val;
705		break;
706	case 2:
707		_val = *(u16 *)val;
708		break;
709	case 4:
710		_val = *(u32 *)val;
711		break;
712	case 8:
713		_val = *(u64 *)val;
714		break;
715	default:
716		return false;
717	}
718
719	return _val == p->datamatch ? true : false;
720}
721
722/* MMIO/PIO writes trigger an event if the addr/val match */
723static int
724ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr,
725		int len, const void *val)
726{
727	struct _ioeventfd *p = to_ioeventfd(this);
728
729	if (!ioeventfd_in_range(p, addr, len, val))
730		return -EOPNOTSUPP;
731
732	eventfd_signal(p->eventfd, 1);
733	return 0;
734}
735
736/*
737 * This function is called as KVM is completely shutting down.  We do not
738 * need to worry about locking just nuke anything we have as quickly as possible
739 */
740static void
741ioeventfd_destructor(struct kvm_io_device *this)
742{
743	struct _ioeventfd *p = to_ioeventfd(this);
744
745	ioeventfd_release(p);
746}
747
748static const struct kvm_io_device_ops ioeventfd_ops = {
749	.write      = ioeventfd_write,
750	.destructor = ioeventfd_destructor,
751};
752
753/* assumes kvm->slots_lock held */
754static bool
755ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
756{
757	struct _ioeventfd *_p;
758
759	list_for_each_entry(_p, &kvm->ioeventfds, list)
760		if (_p->bus_idx == p->bus_idx &&
761		    _p->addr == p->addr &&
762		    (!_p->length || !p->length ||
763		     (_p->length == p->length &&
764		      (_p->wildcard || p->wildcard ||
765		       _p->datamatch == p->datamatch))))
766			return true;
767
768	return false;
769}
770
771static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags)
772{
773	if (flags & KVM_IOEVENTFD_FLAG_PIO)
774		return KVM_PIO_BUS;
775	if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY)
776		return KVM_VIRTIO_CCW_NOTIFY_BUS;
777	return KVM_MMIO_BUS;
778}
779
780static int kvm_assign_ioeventfd_idx(struct kvm *kvm,
781				enum kvm_bus bus_idx,
782				struct kvm_ioeventfd *args)
783{
784
785	struct eventfd_ctx *eventfd;
786	struct _ioeventfd *p;
787	int ret;
788
789	eventfd = eventfd_ctx_fdget(args->fd);
790	if (IS_ERR(eventfd))
791		return PTR_ERR(eventfd);
792
793	p = kzalloc(sizeof(*p), GFP_KERNEL);
794	if (!p) {
795		ret = -ENOMEM;
796		goto fail;
797	}
798
799	INIT_LIST_HEAD(&p->list);
800	p->addr    = args->addr;
801	p->bus_idx = bus_idx;
802	p->length  = args->len;
803	p->eventfd = eventfd;
804
805	/* The datamatch feature is optional, otherwise this is a wildcard */
806	if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
807		p->datamatch = args->datamatch;
808	else
809		p->wildcard = true;
810
811	mutex_lock(&kvm->slots_lock);
812
813	/* Verify that there isn't a match already */
814	if (ioeventfd_check_collision(kvm, p)) {
815		ret = -EEXIST;
816		goto unlock_fail;
817	}
818
819	kvm_iodevice_init(&p->dev, &ioeventfd_ops);
820
821	ret = kvm_io_bus_register_dev(kvm, bus_idx, p->addr, p->length,
822				      &p->dev);
823	if (ret < 0)
824		goto unlock_fail;
825
826	kvm->buses[bus_idx]->ioeventfd_count++;
827	list_add_tail(&p->list, &kvm->ioeventfds);
828
829	mutex_unlock(&kvm->slots_lock);
830
831	return 0;
832
833unlock_fail:
834	mutex_unlock(&kvm->slots_lock);
835
836fail:
837	kfree(p);
838	eventfd_ctx_put(eventfd);
839
840	return ret;
841}
842
843static int
844kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
845			   struct kvm_ioeventfd *args)
846{
847	struct _ioeventfd        *p, *tmp;
848	struct eventfd_ctx       *eventfd;
849	int                       ret = -ENOENT;
850
851	eventfd = eventfd_ctx_fdget(args->fd);
852	if (IS_ERR(eventfd))
853		return PTR_ERR(eventfd);
854
855	mutex_lock(&kvm->slots_lock);
856
857	list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
858		bool wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
859
860		if (p->bus_idx != bus_idx ||
861		    p->eventfd != eventfd  ||
862		    p->addr != args->addr  ||
863		    p->length != args->len ||
864		    p->wildcard != wildcard)
865			continue;
866
867		if (!p->wildcard && p->datamatch != args->datamatch)
868			continue;
869
870		kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
871		kvm->buses[bus_idx]->ioeventfd_count--;
872		ioeventfd_release(p);
873		ret = 0;
874		break;
875	}
876
877	mutex_unlock(&kvm->slots_lock);
878
879	eventfd_ctx_put(eventfd);
880
881	return ret;
882}
883
884static int kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
885{
886	enum kvm_bus bus_idx = ioeventfd_bus_from_flags(args->flags);
887	int ret = kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
888
889	if (!args->len && bus_idx == KVM_MMIO_BUS)
890		kvm_deassign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
891
892	return ret;
893}
894
895static int
896kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
897{
898	enum kvm_bus              bus_idx;
899	int ret;
900
901	bus_idx = ioeventfd_bus_from_flags(args->flags);
902	/* must be natural-word sized, or 0 to ignore length */
903	switch (args->len) {
904	case 0:
905	case 1:
906	case 2:
907	case 4:
908	case 8:
909		break;
910	default:
911		return -EINVAL;
912	}
913
914	/* check for range overflow */
915	if (args->addr + args->len < args->addr)
916		return -EINVAL;
917
918	/* check for extra flags that we don't understand */
919	if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
920		return -EINVAL;
921
922	/* ioeventfd with no length can't be combined with DATAMATCH */
923	if (!args->len && (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH))
924		return -EINVAL;
925
926	ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args);
927	if (ret)
928		goto fail;
929
930	/* When length is ignored, MMIO is also put on a separate bus, for
931	 * faster lookups.
932	 */
933	if (!args->len && bus_idx == KVM_MMIO_BUS) {
934		ret = kvm_assign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
935		if (ret < 0)
936			goto fast_fail;
937	}
938
939	return 0;
940
941fast_fail:
942	kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
943fail:
944	return ret;
945}
946
947int
948kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
949{
950	if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
951		return kvm_deassign_ioeventfd(kvm, args);
952
953	return kvm_assign_ioeventfd(kvm, args);
954}
955