diff options
Diffstat (limited to 'kernel/virt/kvm/eventfd.c')
| -rw-r--r-- | kernel/virt/kvm/eventfd.c | 928 |
1 files changed, 928 insertions, 0 deletions
diff --git a/kernel/virt/kvm/eventfd.c b/kernel/virt/kvm/eventfd.c new file mode 100644 index 000000000..9ff4193df --- /dev/null +++ b/kernel/virt/kvm/eventfd.c @@ -0,0 +1,928 @@ +/* + * kvm eventfd support - use eventfd objects to signal various KVM events + * + * Copyright 2009 Novell. All Rights Reserved. + * Copyright 2010 Red Hat, Inc. and/or its affiliates. + * + * Author: + * Gregory Haskins <ghaskins@novell.com> + * + * This file is free software; you can redistribute it and/or modify + * it under the terms of version 2 of the GNU General Public License + * as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. + */ + +#include <linux/kvm_host.h> +#include <linux/kvm.h> +#include <linux/workqueue.h> +#include <linux/syscalls.h> +#include <linux/wait.h> +#include <linux/poll.h> +#include <linux/file.h> +#include <linux/list.h> +#include <linux/eventfd.h> +#include <linux/kernel.h> +#include <linux/srcu.h> +#include <linux/slab.h> +#include <linux/seqlock.h> +#include <trace/events/kvm.h> + +#include <kvm/iodev.h> + +#ifdef CONFIG_HAVE_KVM_IRQFD +/* + * -------------------------------------------------------------------- + * irqfd: Allows an fd to be used to inject an interrupt to the guest + * + * Credit goes to Avi Kivity for the original idea. + * -------------------------------------------------------------------- + */ + +/* + * Resampling irqfds are a special variety of irqfds used to emulate + * level triggered interrupts. The interrupt is asserted on eventfd + * trigger. On acknowledgement through the irq ack notifier, the + * interrupt is de-asserted and userspace is notified through the + * resamplefd. All resamplers on the same gsi are de-asserted + * together, so we don't need to track the state of each individual + * user. We can also therefore share the same irq source ID. + */ +struct _irqfd_resampler { + struct kvm *kvm; + /* + * List of resampling struct _irqfd objects sharing this gsi. + * RCU list modified under kvm->irqfds.resampler_lock + */ + struct list_head list; + struct kvm_irq_ack_notifier notifier; + /* + * Entry in list of kvm->irqfd.resampler_list. Use for sharing + * resamplers among irqfds on the same gsi. + * Accessed and modified under kvm->irqfds.resampler_lock + */ + struct list_head link; +}; + +struct _irqfd { + /* Used for MSI fast-path */ + struct kvm *kvm; + wait_queue_t wait; + /* Update side is protected by irqfds.lock */ + struct kvm_kernel_irq_routing_entry irq_entry; + seqcount_t irq_entry_sc; + /* Used for level IRQ fast-path */ + int gsi; + struct work_struct inject; + /* The resampler used by this irqfd (resampler-only) */ + struct _irqfd_resampler *resampler; + /* Eventfd notified on resample (resampler-only) */ + struct eventfd_ctx *resamplefd; + /* Entry in list of irqfds for a resampler (resampler-only) */ + struct list_head resampler_link; + /* Used for setup/shutdown */ + struct eventfd_ctx *eventfd; + struct list_head list; + poll_table pt; + struct work_struct shutdown; +}; + +static struct workqueue_struct *irqfd_cleanup_wq; + +static void +irqfd_inject(struct work_struct *work) +{ + struct _irqfd *irqfd = container_of(work, struct _irqfd, inject); + struct kvm *kvm = irqfd->kvm; + + if (!irqfd->resampler) { + kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1, + false); + kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0, + false); + } else + kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID, + irqfd->gsi, 1, false); +} + +/* + * Since resampler irqfds share an IRQ source ID, we de-assert once + * then notify all of the resampler irqfds using this GSI. We can't + * do multiple de-asserts or we risk racing with incoming re-asserts. + */ +static void +irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian) +{ + struct _irqfd_resampler *resampler; + struct kvm *kvm; + struct _irqfd *irqfd; + int idx; + + resampler = container_of(kian, struct _irqfd_resampler, notifier); + kvm = resampler->kvm; + + kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID, + resampler->notifier.gsi, 0, false); + + idx = srcu_read_lock(&kvm->irq_srcu); + + list_for_each_entry_rcu(irqfd, &resampler->list, resampler_link) + eventfd_signal(irqfd->resamplefd, 1); + + srcu_read_unlock(&kvm->irq_srcu, idx); +} + +static void +irqfd_resampler_shutdown(struct _irqfd *irqfd) +{ + struct _irqfd_resampler *resampler = irqfd->resampler; + struct kvm *kvm = resampler->kvm; + + mutex_lock(&kvm->irqfds.resampler_lock); + + list_del_rcu(&irqfd->resampler_link); + synchronize_srcu(&kvm->irq_srcu); + + if (list_empty(&resampler->list)) { + list_del(&resampler->link); + kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier); + kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID, + resampler->notifier.gsi, 0, false); + kfree(resampler); + } + + mutex_unlock(&kvm->irqfds.resampler_lock); +} + +/* + * Race-free decouple logic (ordering is critical) + */ +static void +irqfd_shutdown(struct work_struct *work) +{ + struct _irqfd *irqfd = container_of(work, struct _irqfd, shutdown); + u64 cnt; + + /* + * Synchronize with the wait-queue and unhook ourselves to prevent + * further events. + */ + eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt); + + /* + * We know no new events will be scheduled at this point, so block + * until all previously outstanding events have completed + */ + flush_work(&irqfd->inject); + + if (irqfd->resampler) { + irqfd_resampler_shutdown(irqfd); + eventfd_ctx_put(irqfd->resamplefd); + } + + /* + * It is now safe to release the object's resources + */ + eventfd_ctx_put(irqfd->eventfd); + kfree(irqfd); +} + + +/* assumes kvm->irqfds.lock is held */ +static bool +irqfd_is_active(struct _irqfd *irqfd) +{ + return list_empty(&irqfd->list) ? false : true; +} + +/* + * Mark the irqfd as inactive and schedule it for removal + * + * assumes kvm->irqfds.lock is held + */ +static void +irqfd_deactivate(struct _irqfd *irqfd) +{ + BUG_ON(!irqfd_is_active(irqfd)); + + list_del_init(&irqfd->list); + + queue_work(irqfd_cleanup_wq, &irqfd->shutdown); +} + +/* + * Called with wqh->lock held and interrupts disabled + */ +static int +irqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key) +{ + struct _irqfd *irqfd = container_of(wait, struct _irqfd, wait); + unsigned long flags = (unsigned long)key; + struct kvm_kernel_irq_routing_entry irq; + struct kvm *kvm = irqfd->kvm; + unsigned seq; + int idx; + + if (flags & POLLIN) { + idx = srcu_read_lock(&kvm->irq_srcu); + do { + seq = read_seqcount_begin(&irqfd->irq_entry_sc); + irq = irqfd->irq_entry; + } while (read_seqcount_retry(&irqfd->irq_entry_sc, seq)); + /* An event has been signaled, inject an interrupt */ + if (irq.type == KVM_IRQ_ROUTING_MSI) + kvm_set_msi(&irq, kvm, KVM_USERSPACE_IRQ_SOURCE_ID, 1, + false); + else + schedule_work(&irqfd->inject); + srcu_read_unlock(&kvm->irq_srcu, idx); + } + + if (flags & POLLHUP) { + /* The eventfd is closing, detach from KVM */ + unsigned long flags; + + spin_lock_irqsave(&kvm->irqfds.lock, flags); + + /* + * We must check if someone deactivated the irqfd before + * we could acquire the irqfds.lock since the item is + * deactivated from the KVM side before it is unhooked from + * the wait-queue. If it is already deactivated, we can + * simply return knowing the other side will cleanup for us. + * We cannot race against the irqfd going away since the + * other side is required to acquire wqh->lock, which we hold + */ + if (irqfd_is_active(irqfd)) + irqfd_deactivate(irqfd); + + spin_unlock_irqrestore(&kvm->irqfds.lock, flags); + } + + return 0; +} + +static void +irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh, + poll_table *pt) +{ + struct _irqfd *irqfd = container_of(pt, struct _irqfd, pt); + add_wait_queue(wqh, &irqfd->wait); +} + +/* Must be called under irqfds.lock */ +static void irqfd_update(struct kvm *kvm, struct _irqfd *irqfd) +{ + struct kvm_kernel_irq_routing_entry *e; + struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS]; + int i, n_entries; + + n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi); + + write_seqcount_begin(&irqfd->irq_entry_sc); + + irqfd->irq_entry.type = 0; + + e = entries; + for (i = 0; i < n_entries; ++i, ++e) { + /* Only fast-path MSI. */ + if (e->type == KVM_IRQ_ROUTING_MSI) + irqfd->irq_entry = *e; + } + + write_seqcount_end(&irqfd->irq_entry_sc); +} + +static int +kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args) +{ + struct _irqfd *irqfd, *tmp; + struct fd f; + struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL; + int ret; + unsigned int events; + int idx; + + if (!kvm_arch_intc_initialized(kvm)) + return -EAGAIN; + + irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL); + if (!irqfd) + return -ENOMEM; + + irqfd->kvm = kvm; + irqfd->gsi = args->gsi; + INIT_LIST_HEAD(&irqfd->list); + INIT_WORK(&irqfd->inject, irqfd_inject); + INIT_WORK(&irqfd->shutdown, irqfd_shutdown); + seqcount_init(&irqfd->irq_entry_sc); + + f = fdget(args->fd); + if (!f.file) { + ret = -EBADF; + goto out; + } + + eventfd = eventfd_ctx_fileget(f.file); + if (IS_ERR(eventfd)) { + ret = PTR_ERR(eventfd); + goto fail; + } + + irqfd->eventfd = eventfd; + + if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) { + struct _irqfd_resampler *resampler; + + resamplefd = eventfd_ctx_fdget(args->resamplefd); + if (IS_ERR(resamplefd)) { + ret = PTR_ERR(resamplefd); + goto fail; + } + + irqfd->resamplefd = resamplefd; + INIT_LIST_HEAD(&irqfd->resampler_link); + + mutex_lock(&kvm->irqfds.resampler_lock); + + list_for_each_entry(resampler, + &kvm->irqfds.resampler_list, link) { + if (resampler->notifier.gsi == irqfd->gsi) { + irqfd->resampler = resampler; + break; + } + } + + if (!irqfd->resampler) { + resampler = kzalloc(sizeof(*resampler), GFP_KERNEL); + if (!resampler) { + ret = -ENOMEM; + mutex_unlock(&kvm->irqfds.resampler_lock); + goto fail; + } + + resampler->kvm = kvm; + INIT_LIST_HEAD(&resampler->list); + resampler->notifier.gsi = irqfd->gsi; + resampler->notifier.irq_acked = irqfd_resampler_ack; + INIT_LIST_HEAD(&resampler->link); + + list_add(&resampler->link, &kvm->irqfds.resampler_list); + kvm_register_irq_ack_notifier(kvm, + &resampler->notifier); + irqfd->resampler = resampler; + } + + list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list); + synchronize_srcu(&kvm->irq_srcu); + + mutex_unlock(&kvm->irqfds.resampler_lock); + } + + /* + * Install our own custom wake-up handling so we are notified via + * a callback whenever someone signals the underlying eventfd + */ + init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup); + init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc); + + spin_lock_irq(&kvm->irqfds.lock); + + ret = 0; + list_for_each_entry(tmp, &kvm->irqfds.items, list) { + if (irqfd->eventfd != tmp->eventfd) + continue; + /* This fd is used for another irq already. */ + ret = -EBUSY; + spin_unlock_irq(&kvm->irqfds.lock); + goto fail; + } + + idx = srcu_read_lock(&kvm->irq_srcu); + irqfd_update(kvm, irqfd); + srcu_read_unlock(&kvm->irq_srcu, idx); + + list_add_tail(&irqfd->list, &kvm->irqfds.items); + + spin_unlock_irq(&kvm->irqfds.lock); + + /* + * Check if there was an event already pending on the eventfd + * before we registered, and trigger it as if we didn't miss it. + */ + events = f.file->f_op->poll(f.file, &irqfd->pt); + + if (events & POLLIN) + schedule_work(&irqfd->inject); + + /* + * do not drop the file until the irqfd is fully initialized, otherwise + * we might race against the POLLHUP + */ + fdput(f); + + return 0; + +fail: + if (irqfd->resampler) + irqfd_resampler_shutdown(irqfd); + + if (resamplefd && !IS_ERR(resamplefd)) + eventfd_ctx_put(resamplefd); + + if (eventfd && !IS_ERR(eventfd)) + eventfd_ctx_put(eventfd); + + fdput(f); + +out: + kfree(irqfd); + return ret; +} + +bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin) +{ + struct kvm_irq_ack_notifier *kian; + int gsi, idx; + + idx = srcu_read_lock(&kvm->irq_srcu); + gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin); + if (gsi != -1) + hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list, + link) + if (kian->gsi == gsi) { + srcu_read_unlock(&kvm->irq_srcu, idx); + return true; + } + + srcu_read_unlock(&kvm->irq_srcu, idx); + + return false; +} +EXPORT_SYMBOL_GPL(kvm_irq_has_notifier); + +void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin) +{ + struct kvm_irq_ack_notifier *kian; + int gsi, idx; + + trace_kvm_ack_irq(irqchip, pin); + + idx = srcu_read_lock(&kvm->irq_srcu); + gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin); + if (gsi != -1) + hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list, + link) + if (kian->gsi == gsi) + kian->irq_acked(kian); + srcu_read_unlock(&kvm->irq_srcu, idx); +} + +void kvm_register_irq_ack_notifier(struct kvm *kvm, + struct kvm_irq_ack_notifier *kian) +{ + mutex_lock(&kvm->irq_lock); + hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list); + mutex_unlock(&kvm->irq_lock); + kvm_vcpu_request_scan_ioapic(kvm); +} + +void kvm_unregister_irq_ack_notifier(struct kvm *kvm, + struct kvm_irq_ack_notifier *kian) +{ + mutex_lock(&kvm->irq_lock); + hlist_del_init_rcu(&kian->link); + mutex_unlock(&kvm->irq_lock); + synchronize_srcu(&kvm->irq_srcu); + kvm_vcpu_request_scan_ioapic(kvm); +} +#endif + +void +kvm_eventfd_init(struct kvm *kvm) +{ +#ifdef CONFIG_HAVE_KVM_IRQFD + spin_lock_init(&kvm->irqfds.lock); + INIT_LIST_HEAD(&kvm->irqfds.items); + INIT_LIST_HEAD(&kvm->irqfds.resampler_list); + mutex_init(&kvm->irqfds.resampler_lock); +#endif + INIT_LIST_HEAD(&kvm->ioeventfds); +} + +#ifdef CONFIG_HAVE_KVM_IRQFD +/* + * shutdown any irqfd's that match fd+gsi + */ +static int +kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args) +{ + struct _irqfd *irqfd, *tmp; + struct eventfd_ctx *eventfd; + + eventfd = eventfd_ctx_fdget(args->fd); + if (IS_ERR(eventfd)) + return PTR_ERR(eventfd); + + spin_lock_irq(&kvm->irqfds.lock); + + list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) { + if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) { + /* + * This clearing of irq_entry.type is needed for when + * another thread calls kvm_irq_routing_update before + * we flush workqueue below (we synchronize with + * kvm_irq_routing_update using irqfds.lock). + */ + write_seqcount_begin(&irqfd->irq_entry_sc); + irqfd->irq_entry.type = 0; + write_seqcount_end(&irqfd->irq_entry_sc); + irqfd_deactivate(irqfd); + } + } + + spin_unlock_irq(&kvm->irqfds.lock); + eventfd_ctx_put(eventfd); + + /* + * Block until we know all outstanding shutdown jobs have completed + * so that we guarantee there will not be any more interrupts on this + * gsi once this deassign function returns. + */ + flush_workqueue(irqfd_cleanup_wq); + + return 0; +} + +int +kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args) +{ + if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE)) + return -EINVAL; + + if (args->flags & KVM_IRQFD_FLAG_DEASSIGN) + return kvm_irqfd_deassign(kvm, args); + + return kvm_irqfd_assign(kvm, args); +} + +/* + * This function is called as the kvm VM fd is being released. Shutdown all + * irqfds that still remain open + */ +void +kvm_irqfd_release(struct kvm *kvm) +{ + struct _irqfd *irqfd, *tmp; + + spin_lock_irq(&kvm->irqfds.lock); + + list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) + irqfd_deactivate(irqfd); + + spin_unlock_irq(&kvm->irqfds.lock); + + /* + * Block until we know all outstanding shutdown jobs have completed + * since we do not take a kvm* reference. + */ + flush_workqueue(irqfd_cleanup_wq); + +} + +/* + * Take note of a change in irq routing. + * Caller must invoke synchronize_srcu(&kvm->irq_srcu) afterwards. + */ +void kvm_irq_routing_update(struct kvm *kvm) +{ + struct _irqfd *irqfd; + + spin_lock_irq(&kvm->irqfds.lock); + + list_for_each_entry(irqfd, &kvm->irqfds.items, list) + irqfd_update(kvm, irqfd); + + spin_unlock_irq(&kvm->irqfds.lock); +} + +/* + * create a host-wide workqueue for issuing deferred shutdown requests + * aggregated from all vm* instances. We need our own isolated single-thread + * queue to prevent deadlock against flushing the normal work-queue. + */ +int kvm_irqfd_init(void) +{ + irqfd_cleanup_wq = create_singlethread_workqueue("kvm-irqfd-cleanup"); + if (!irqfd_cleanup_wq) + return -ENOMEM; + + return 0; +} + +void kvm_irqfd_exit(void) +{ + destroy_workqueue(irqfd_cleanup_wq); +} +#endif + +/* + * -------------------------------------------------------------------- + * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal. + * + * userspace can register a PIO/MMIO address with an eventfd for receiving + * notification when the memory has been touched. + * -------------------------------------------------------------------- + */ + +struct _ioeventfd { + struct list_head list; + u64 addr; + int length; + struct eventfd_ctx *eventfd; + u64 datamatch; + struct kvm_io_device dev; + u8 bus_idx; + bool wildcard; +}; + +static inline struct _ioeventfd * +to_ioeventfd(struct kvm_io_device *dev) +{ + return container_of(dev, struct _ioeventfd, dev); +} + +static void +ioeventfd_release(struct _ioeventfd *p) +{ + eventfd_ctx_put(p->eventfd); + list_del(&p->list); + kfree(p); +} + +static bool +ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val) +{ + u64 _val; + + if (addr != p->addr) + /* address must be precise for a hit */ + return false; + + if (!p->length) + /* length = 0 means only look at the address, so always a hit */ + return true; + + if (len != p->length) + /* address-range must be precise for a hit */ + return false; + + if (p->wildcard) + /* all else equal, wildcard is always a hit */ + return true; + + /* otherwise, we have to actually compare the data */ + + BUG_ON(!IS_ALIGNED((unsigned long)val, len)); + + switch (len) { + case 1: + _val = *(u8 *)val; + break; + case 2: + _val = *(u16 *)val; + break; + case 4: + _val = *(u32 *)val; + break; + case 8: + _val = *(u64 *)val; + break; + default: + return false; + } + + return _val == p->datamatch ? true : false; +} + +/* MMIO/PIO writes trigger an event if the addr/val match */ +static int +ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr, + int len, const void *val) +{ + struct _ioeventfd *p = to_ioeventfd(this); + + if (!ioeventfd_in_range(p, addr, len, val)) + return -EOPNOTSUPP; + + eventfd_signal(p->eventfd, 1); + return 0; +} + +/* + * This function is called as KVM is completely shutting down. We do not + * need to worry about locking just nuke anything we have as quickly as possible + */ +static void +ioeventfd_destructor(struct kvm_io_device *this) +{ + struct _ioeventfd *p = to_ioeventfd(this); + + ioeventfd_release(p); +} + +static const struct kvm_io_device_ops ioeventfd_ops = { + .write = ioeventfd_write, + .destructor = ioeventfd_destructor, +}; + +/* assumes kvm->slots_lock held */ +static bool +ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p) +{ + struct _ioeventfd *_p; + + list_for_each_entry(_p, &kvm->ioeventfds, list) + if (_p->bus_idx == p->bus_idx && + _p->addr == p->addr && + (!_p->length || !p->length || + (_p->length == p->length && + (_p->wildcard || p->wildcard || + _p->datamatch == p->datamatch)))) + return true; + + return false; +} + +static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags) +{ + if (flags & KVM_IOEVENTFD_FLAG_PIO) + return KVM_PIO_BUS; + if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY) + return KVM_VIRTIO_CCW_NOTIFY_BUS; + return KVM_MMIO_BUS; +} + +static int +kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args) +{ + enum kvm_bus bus_idx; + struct _ioeventfd *p; + struct eventfd_ctx *eventfd; + int ret; + + bus_idx = ioeventfd_bus_from_flags(args->flags); + /* must be natural-word sized, or 0 to ignore length */ + switch (args->len) { + case 0: + case 1: + case 2: + case 4: + case 8: + break; + default: + return -EINVAL; + } + + /* check for range overflow */ + if (args->addr + args->len < args->addr) + return -EINVAL; + + /* check for extra flags that we don't understand */ + if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK) + return -EINVAL; + + /* ioeventfd with no length can't be combined with DATAMATCH */ + if (!args->len && + args->flags & (KVM_IOEVENTFD_FLAG_PIO | + KVM_IOEVENTFD_FLAG_DATAMATCH)) + return -EINVAL; + + eventfd = eventfd_ctx_fdget(args->fd); + if (IS_ERR(eventfd)) + return PTR_ERR(eventfd); + + p = kzalloc(sizeof(*p), GFP_KERNEL); + if (!p) { + ret = -ENOMEM; + goto fail; + } + + INIT_LIST_HEAD(&p->list); + p->addr = args->addr; + p->bus_idx = bus_idx; + p->length = args->len; + p->eventfd = eventfd; + + /* The datamatch feature is optional, otherwise this is a wildcard */ + if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH) + p->datamatch = args->datamatch; + else + p->wildcard = true; + + mutex_lock(&kvm->slots_lock); + + /* Verify that there isn't a match already */ + if (ioeventfd_check_collision(kvm, p)) { + ret = -EEXIST; + goto unlock_fail; + } + + kvm_iodevice_init(&p->dev, &ioeventfd_ops); + + ret = kvm_io_bus_register_dev(kvm, bus_idx, p->addr, p->length, + &p->dev); + if (ret < 0) + goto unlock_fail; + + /* When length is ignored, MMIO is also put on a separate bus, for + * faster lookups. + */ + if (!args->len && !(args->flags & KVM_IOEVENTFD_FLAG_PIO)) { + ret = kvm_io_bus_register_dev(kvm, KVM_FAST_MMIO_BUS, + p->addr, 0, &p->dev); + if (ret < 0) + goto register_fail; + } + + kvm->buses[bus_idx]->ioeventfd_count++; + list_add_tail(&p->list, &kvm->ioeventfds); + + mutex_unlock(&kvm->slots_lock); + + return 0; + +register_fail: + kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev); +unlock_fail: + mutex_unlock(&kvm->slots_lock); + +fail: + kfree(p); + eventfd_ctx_put(eventfd); + + return ret; +} + +static int +kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args) +{ + enum kvm_bus bus_idx; + struct _ioeventfd *p, *tmp; + struct eventfd_ctx *eventfd; + int ret = -ENOENT; + + bus_idx = ioeventfd_bus_from_flags(args->flags); + eventfd = eventfd_ctx_fdget(args->fd); + if (IS_ERR(eventfd)) + return PTR_ERR(eventfd); + + mutex_lock(&kvm->slots_lock); + + list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) { + bool wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH); + + if (p->bus_idx != bus_idx || + p->eventfd != eventfd || + p->addr != args->addr || + p->length != args->len || + p->wildcard != wildcard) + continue; + + if (!p->wildcard && p->datamatch != args->datamatch) + continue; + + kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev); + if (!p->length) { + kvm_io_bus_unregister_dev(kvm, KVM_FAST_MMIO_BUS, + &p->dev); + } + kvm->buses[bus_idx]->ioeventfd_count--; + ioeventfd_release(p); + ret = 0; + break; + } + + mutex_unlock(&kvm->slots_lock); + + eventfd_ctx_put(eventfd); + + return ret; +} + +int +kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args) +{ + if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN) + return kvm_deassign_ioeventfd(kvm, args); + + return kvm_assign_ioeventfd(kvm, args); +} |