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-rw-r--r--virt/kvm/eventfd.c964
1 files changed, 964 insertions, 0 deletions
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
new file mode 100644
index 000000000..518cd8dc3
--- /dev/null
+++ b/virt/kvm/eventfd.c
@@ -0,0 +1,964 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * 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>
+ */
+
+#include <linux/kvm_host.h>
+#include <linux/kvm.h>
+#include <linux/kvm_irqfd.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 <linux/irqbypass.h>
+#include <trace/events/kvm.h>
+
+#include <kvm/iodev.h>
+
+#ifdef CONFIG_HAVE_KVM_IRQFD
+
+static struct workqueue_struct *irqfd_cleanup_wq;
+
+bool __attribute__((weak))
+kvm_arch_irqfd_allowed(struct kvm *kvm, struct kvm_irqfd *args)
+{
+ return true;
+}
+
+static void
+irqfd_inject(struct work_struct *work)
+{
+ struct kvm_kernel_irqfd *irqfd =
+ container_of(work, struct kvm_kernel_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 kvm_kernel_irqfd_resampler *resampler;
+ struct kvm *kvm;
+ struct kvm_kernel_irqfd *irqfd;
+ int idx;
+
+ resampler = container_of(kian,
+ struct kvm_kernel_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 kvm_kernel_irqfd *irqfd)
+{
+ struct kvm_kernel_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 kvm_kernel_irqfd *irqfd =
+ container_of(work, struct kvm_kernel_irqfd, shutdown);
+ struct kvm *kvm = irqfd->kvm;
+ u64 cnt;
+
+ /* Make sure irqfd has been initialized in assign path. */
+ synchronize_srcu(&kvm->irq_srcu);
+
+ /*
+ * 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
+ */
+#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
+ irq_bypass_unregister_consumer(&irqfd->consumer);
+#endif
+ eventfd_ctx_put(irqfd->eventfd);
+ kfree(irqfd);
+}
+
+
+/* assumes kvm->irqfds.lock is held */
+static bool
+irqfd_is_active(struct kvm_kernel_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 kvm_kernel_irqfd *irqfd)
+{
+ BUG_ON(!irqfd_is_active(irqfd));
+
+ list_del_init(&irqfd->list);
+
+ queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
+}
+
+int __attribute__((weak)) kvm_arch_set_irq_inatomic(
+ struct kvm_kernel_irq_routing_entry *irq,
+ struct kvm *kvm, int irq_source_id,
+ int level,
+ bool line_status)
+{
+ return -EWOULDBLOCK;
+}
+
+/*
+ * Called with wqh->lock held and interrupts disabled
+ */
+static int
+irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
+{
+ struct kvm_kernel_irqfd *irqfd =
+ container_of(wait, struct kvm_kernel_irqfd, wait);
+ __poll_t flags = key_to_poll(key);
+ struct kvm_kernel_irq_routing_entry irq;
+ struct kvm *kvm = irqfd->kvm;
+ unsigned seq;
+ int idx;
+
+ if (flags & EPOLLIN) {
+ 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 (kvm_arch_set_irq_inatomic(&irq, kvm,
+ KVM_USERSPACE_IRQ_SOURCE_ID, 1,
+ false) == -EWOULDBLOCK)
+ schedule_work(&irqfd->inject);
+ srcu_read_unlock(&kvm->irq_srcu, idx);
+ }
+
+ if (flags & EPOLLHUP) {
+ /* The eventfd is closing, detach from KVM */
+ unsigned long iflags;
+
+ spin_lock_irqsave(&kvm->irqfds.lock, iflags);
+
+ /*
+ * 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, iflags);
+ }
+
+ return 0;
+}
+
+static void
+irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
+ poll_table *pt)
+{
+ struct kvm_kernel_irqfd *irqfd =
+ container_of(pt, struct kvm_kernel_irqfd, pt);
+ add_wait_queue(wqh, &irqfd->wait);
+}
+
+/* Must be called under irqfds.lock */
+static void irqfd_update(struct kvm *kvm, struct kvm_kernel_irqfd *irqfd)
+{
+ struct kvm_kernel_irq_routing_entry *e;
+ struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
+ int n_entries;
+
+ n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);
+
+ write_seqcount_begin(&irqfd->irq_entry_sc);
+
+ e = entries;
+ if (n_entries == 1)
+ irqfd->irq_entry = *e;
+ else
+ irqfd->irq_entry.type = 0;
+
+ write_seqcount_end(&irqfd->irq_entry_sc);
+}
+
+#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
+void __attribute__((weak)) kvm_arch_irq_bypass_stop(
+ struct irq_bypass_consumer *cons)
+{
+}
+
+void __attribute__((weak)) kvm_arch_irq_bypass_start(
+ struct irq_bypass_consumer *cons)
+{
+}
+
+int __attribute__((weak)) kvm_arch_update_irqfd_routing(
+ struct kvm *kvm, unsigned int host_irq,
+ uint32_t guest_irq, bool set)
+{
+ return 0;
+}
+#endif
+
+static int
+kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
+{
+ struct kvm_kernel_irqfd *irqfd, *tmp;
+ struct fd f;
+ struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
+ int ret;
+ __poll_t events;
+ int idx;
+
+ if (!kvm_arch_intc_initialized(kvm))
+ return -EAGAIN;
+
+ if (!kvm_arch_irqfd_allowed(kvm, args))
+ return -EINVAL;
+
+ irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL_ACCOUNT);
+ 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_spinlock_init(&irqfd->irq_entry_sc, &kvm->irqfds.lock);
+
+ 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 kvm_kernel_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_ACCOUNT);
+ 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);
+
+ 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 = vfs_poll(f.file, &irqfd->pt);
+
+ if (events & EPOLLIN)
+ schedule_work(&irqfd->inject);
+
+#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
+ if (kvm_arch_has_irq_bypass()) {
+ irqfd->consumer.token = (void *)irqfd->eventfd;
+ irqfd->consumer.add_producer = kvm_arch_irq_bypass_add_producer;
+ irqfd->consumer.del_producer = kvm_arch_irq_bypass_del_producer;
+ irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
+ irqfd->consumer.start = kvm_arch_irq_bypass_start;
+ ret = irq_bypass_register_consumer(&irqfd->consumer);
+ if (ret)
+ pr_info("irq bypass consumer (token %p) registration fails: %d\n",
+ irqfd->consumer.token, ret);
+ }
+#endif
+
+ srcu_read_unlock(&kvm->irq_srcu, idx);
+
+ /*
+ * do not drop the file until the irqfd is fully initialized, otherwise
+ * we might race against the EPOLLHUP
+ */
+ 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_srcu(kian, &kvm->irq_ack_notifier_list,
+ link, srcu_read_lock_held(&kvm->irq_srcu))
+ 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_gsi(struct kvm *kvm, int gsi)
+{
+ struct kvm_irq_ack_notifier *kian;
+
+ hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list,
+ link, srcu_read_lock_held(&kvm->irq_srcu))
+ if (kian->gsi == gsi)
+ kian->irq_acked(kian);
+}
+
+void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
+{
+ 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)
+ kvm_notify_acked_gsi(kvm, gsi);
+ 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_arch_post_irq_ack_notifier_list_update(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_arch_post_irq_ack_notifier_list_update(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 kvm_kernel_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 kvm_kernel_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 kvm_kernel_irqfd *irqfd;
+
+ spin_lock_irq(&kvm->irqfds.lock);
+
+ list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
+ irqfd_update(kvm, irqfd);
+
+#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
+ if (irqfd->producer) {
+ int ret = kvm_arch_update_irqfd_routing(
+ irqfd->kvm, irqfd->producer->irq,
+ irqfd->gsi, 1);
+ WARN_ON(ret);
+ }
+#endif
+ }
+
+ 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
+ * queue to ease flushing work items when a VM exits.
+ */
+int kvm_irqfd_init(void)
+{
+ irqfd_cleanup_wq = alloc_workqueue("kvm-irqfd-cleanup", 0, 0);
+ 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;
+}
+
+/* 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_idx(struct kvm *kvm,
+ enum kvm_bus bus_idx,
+ struct kvm_ioeventfd *args)
+{
+
+ struct eventfd_ctx *eventfd;
+ struct _ioeventfd *p;
+ int ret;
+
+ eventfd = eventfd_ctx_fdget(args->fd);
+ if (IS_ERR(eventfd))
+ return PTR_ERR(eventfd);
+
+ p = kzalloc(sizeof(*p), GFP_KERNEL_ACCOUNT);
+ 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;
+
+ kvm_get_bus(kvm, bus_idx)->ioeventfd_count++;
+ list_add_tail(&p->list, &kvm->ioeventfds);
+
+ mutex_unlock(&kvm->slots_lock);
+
+ return 0;
+
+unlock_fail:
+ mutex_unlock(&kvm->slots_lock);
+
+fail:
+ kfree(p);
+ eventfd_ctx_put(eventfd);
+
+ return ret;
+}
+
+static int
+kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
+ struct kvm_ioeventfd *args)
+{
+ struct _ioeventfd *p, *tmp;
+ struct eventfd_ctx *eventfd;
+ struct kvm_io_bus *bus;
+ int ret = -ENOENT;
+ bool wildcard;
+
+ eventfd = eventfd_ctx_fdget(args->fd);
+ if (IS_ERR(eventfd))
+ return PTR_ERR(eventfd);
+
+ wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
+
+ mutex_lock(&kvm->slots_lock);
+
+ list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
+
+ 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);
+ bus = kvm_get_bus(kvm, bus_idx);
+ if (bus)
+ bus->ioeventfd_count--;
+ ioeventfd_release(p);
+ ret = 0;
+ break;
+ }
+
+ mutex_unlock(&kvm->slots_lock);
+
+ eventfd_ctx_put(eventfd);
+
+ return ret;
+}
+
+static int kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
+{
+ enum kvm_bus bus_idx = ioeventfd_bus_from_flags(args->flags);
+ int ret = kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
+
+ if (!args->len && bus_idx == KVM_MMIO_BUS)
+ kvm_deassign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
+
+ return ret;
+}
+
+static int
+kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
+{
+ enum kvm_bus bus_idx;
+ 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_DATAMATCH))
+ return -EINVAL;
+
+ ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args);
+ if (ret)
+ goto fail;
+
+ /* When length is ignored, MMIO is also put on a separate bus, for
+ * faster lookups.
+ */
+ if (!args->len && bus_idx == KVM_MMIO_BUS) {
+ ret = kvm_assign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
+ if (ret < 0)
+ goto fast_fail;
+ }
+
+ return 0;
+
+fast_fail:
+ kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
+fail:
+ 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);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-10 20:52:27 +0000