| /* |
| * kvm eventfd support - use eventfd objects to signal various KVM events |
| * |
| * Copyright 2009 Novell. All Rights Reserved. |
| * |
| * 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/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/srcu.h> |
| |
| /* |
| * -------------------------------------------------------------------- |
| * irqfd: Allows an fd to be used to inject an interrupt to the guest |
| * |
| * Credit goes to Avi Kivity for the original idea. |
| * -------------------------------------------------------------------- |
| */ |
| struct _irqfd { |
| struct mutex lock; |
| struct srcu_struct srcu; |
| struct kvm *kvm; |
| int gsi; |
| struct list_head list; |
| poll_table pt; |
| wait_queue_head_t *wqh; |
| wait_queue_t wait; |
| struct work_struct inject; |
| }; |
| |
| static void |
| irqfd_inject(struct work_struct *work) |
| { |
| struct _irqfd *irqfd = container_of(work, struct _irqfd, inject); |
| struct kvm *kvm; |
| int idx; |
| |
| idx = srcu_read_lock(&irqfd->srcu); |
| |
| kvm = rcu_dereference(irqfd->kvm); |
| if (kvm) { |
| mutex_lock(&kvm->irq_lock); |
| kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1); |
| kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0); |
| mutex_unlock(&kvm->irq_lock); |
| } |
| |
| srcu_read_unlock(&irqfd->srcu, idx); |
| } |
| |
| static void |
| irqfd_disconnect(struct _irqfd *irqfd) |
| { |
| struct kvm *kvm; |
| |
| mutex_lock(&irqfd->lock); |
| |
| kvm = rcu_dereference(irqfd->kvm); |
| rcu_assign_pointer(irqfd->kvm, NULL); |
| |
| mutex_unlock(&irqfd->lock); |
| |
| if (!kvm) |
| return; |
| |
| mutex_lock(&kvm->lock); |
| list_del(&irqfd->list); |
| mutex_unlock(&kvm->lock); |
| |
| /* |
| * It is important to not drop the kvm reference until the next grace |
| * period because there might be lockless references in flight up |
| * until then |
| */ |
| synchronize_srcu(&irqfd->srcu); |
| kvm_put_kvm(kvm); |
| } |
| |
| 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; |
| |
| if (flags & POLLIN) |
| /* |
| * The POLLIN wake_up is called with interrupts disabled. |
| * Therefore we need to defer the IRQ injection until later |
| * since we need to acquire the kvm->lock to do so. |
| */ |
| schedule_work(&irqfd->inject); |
| |
| if (flags & POLLHUP) { |
| /* |
| * The POLLHUP is called unlocked, so it theoretically should |
| * be safe to remove ourselves from the wqh using the locked |
| * variant of remove_wait_queue() |
| */ |
| remove_wait_queue(irqfd->wqh, &irqfd->wait); |
| flush_work(&irqfd->inject); |
| irqfd_disconnect(irqfd); |
| |
| cleanup_srcu_struct(&irqfd->srcu); |
| kfree(irqfd); |
| } |
| |
| 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); |
| |
| irqfd->wqh = wqh; |
| add_wait_queue(wqh, &irqfd->wait); |
| } |
| |
| int |
| kvm_irqfd(struct kvm *kvm, int fd, int gsi, int flags) |
| { |
| struct _irqfd *irqfd; |
| struct file *file = NULL; |
| int ret; |
| unsigned int events; |
| |
| irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL); |
| if (!irqfd) |
| return -ENOMEM; |
| |
| mutex_init(&irqfd->lock); |
| init_srcu_struct(&irqfd->srcu); |
| irqfd->kvm = kvm; |
| irqfd->gsi = gsi; |
| INIT_LIST_HEAD(&irqfd->list); |
| INIT_WORK(&irqfd->inject, irqfd_inject); |
| |
| file = eventfd_fget(fd); |
| if (IS_ERR(file)) { |
| ret = PTR_ERR(file); |
| goto fail; |
| } |
| |
| /* |
| * 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); |
| |
| events = file->f_op->poll(file, &irqfd->pt); |
| |
| kvm_get_kvm(kvm); |
| |
| mutex_lock(&kvm->lock); |
| list_add_tail(&irqfd->list, &kvm->irqfds); |
| mutex_unlock(&kvm->lock); |
| |
| /* |
| * Check if there was an event already queued |
| */ |
| 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 |
| */ |
| fput(file); |
| |
| return 0; |
| |
| fail: |
| if (file && !IS_ERR(file)) |
| fput(file); |
| |
| kfree(irqfd); |
| return ret; |
| } |
| |
| void |
| kvm_irqfd_init(struct kvm *kvm) |
| { |
| INIT_LIST_HEAD(&kvm->irqfds); |
| } |
| |
| void |
| kvm_irqfd_release(struct kvm *kvm) |
| { |
| struct _irqfd *irqfd, *tmp; |
| |
| list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds, list) |
| irqfd_disconnect(irqfd); |
| } |