diff options
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/Kconfig | 4 | ||||
| -rw-r--r-- | virt/kvm/eventfd.c | 329 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 12 |
3 files changed, 345 insertions, 0 deletions
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig index 79e83fc00dc..56c6848d2df 100644 --- a/virt/kvm/Kconfig +++ b/virt/kvm/Kconfig @@ -5,3 +5,7 @@ config HAVE_KVM config HAVE_KVM_IRQCHIP bool + +config HAVE_KVM_EVENTFD + bool + select EVENTFD diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c new file mode 100644 index 00000000000..314012323af --- /dev/null +++ b/virt/kvm/eventfd.c @@ -0,0 +1,329 @@ +/* + * 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> + +/* + * -------------------------------------------------------------------- + * 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 kvm *kvm; + struct eventfd_ctx *eventfd; + int gsi; + struct list_head list; + poll_table pt; + wait_queue_head_t *wqh; + wait_queue_t wait; + struct work_struct inject; + 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; + + mutex_lock(&kvm->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->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); + + /* + * Synchronize with the wait-queue and unhook ourselves to prevent + * further events. + */ + remove_wait_queue(irqfd->wqh, &irqfd->wait); + + /* + * We know no new events will be scheduled at this point, so block + * until all previously outstanding events have completed + */ + flush_work(&irqfd->inject); + + /* + * 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; + + if (flags & POLLIN) + /* An event has been signaled, inject an interrupt */ + schedule_work(&irqfd->inject); + + if (flags & POLLHUP) { + /* The eventfd is closing, detach from KVM */ + struct kvm *kvm = irqfd->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); + + irqfd->wqh = wqh; + add_wait_queue(wqh, &irqfd->wait); +} + +static int +kvm_irqfd_assign(struct kvm *kvm, int fd, int gsi) +{ + struct _irqfd *irqfd; + struct file *file = NULL; + struct eventfd_ctx *eventfd = NULL; + int ret; + unsigned int events; + + irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL); + if (!irqfd) + return -ENOMEM; + + irqfd->kvm = kvm; + irqfd->gsi = gsi; + INIT_LIST_HEAD(&irqfd->list); + INIT_WORK(&irqfd->inject, irqfd_inject); + INIT_WORK(&irqfd->shutdown, irqfd_shutdown); + + file = eventfd_fget(fd); + if (IS_ERR(file)) { + ret = PTR_ERR(file); + goto fail; + } + + eventfd = eventfd_ctx_fileget(file); + if (IS_ERR(eventfd)) { + ret = PTR_ERR(eventfd); + goto fail; + } + + irqfd->eventfd = eventfd; + + /* + * 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); + + spin_lock_irq(&kvm->irqfds.lock); + 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. + */ + 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 (eventfd && !IS_ERR(eventfd)) + eventfd_ctx_put(eventfd); + + if (file && !IS_ERR(file)) + fput(file); + + kfree(irqfd); + return ret; +} + +void +kvm_irqfd_init(struct kvm *kvm) +{ + spin_lock_init(&kvm->irqfds.lock); + INIT_LIST_HEAD(&kvm->irqfds.items); +} + +/* + * shutdown any irqfd's that match fd+gsi + */ +static int +kvm_irqfd_deassign(struct kvm *kvm, int fd, int gsi) +{ + struct _irqfd *irqfd, *tmp; + struct eventfd_ctx *eventfd; + + eventfd = eventfd_ctx_fdget(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 == gsi) + 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, int fd, int gsi, int flags) +{ + if (flags & KVM_IRQFD_FLAG_DEASSIGN) + return kvm_irqfd_deassign(kvm, fd, gsi); + + return kvm_irqfd_assign(kvm, fd, gsi); +} + +/* + * 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); + +} + +/* + * 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. + */ +static int __init irqfd_module_init(void) +{ + irqfd_cleanup_wq = create_singlethread_workqueue("kvm-irqfd-cleanup"); + if (!irqfd_cleanup_wq) + return -ENOMEM; + + return 0; +} + +static void __exit irqfd_module_exit(void) +{ + destroy_workqueue(irqfd_cleanup_wq); +} + +module_init(irqfd_module_init); +module_exit(irqfd_module_exit); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 2884baf1d5f..dee321e5889 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -986,6 +986,7 @@ static struct kvm *kvm_create_vm(void) spin_lock_init(&kvm->mmu_lock); spin_lock_init(&kvm->requests_lock); kvm_io_bus_init(&kvm->pio_bus); + kvm_irqfd_init(kvm); mutex_init(&kvm->lock); kvm_io_bus_init(&kvm->mmio_bus); init_rwsem(&kvm->slots_lock); @@ -1071,6 +1072,8 @@ static int kvm_vm_release(struct inode *inode, struct file *filp) { struct kvm *kvm = filp->private_data; + kvm_irqfd_release(kvm); + kvm_put_kvm(kvm); return 0; } @@ -2222,6 +2225,15 @@ static long kvm_vm_ioctl(struct file *filp, } #endif #endif /* KVM_CAP_IRQ_ROUTING */ + case KVM_IRQFD: { + struct kvm_irqfd data; + + r = -EFAULT; + if (copy_from_user(&data, argp, sizeof data)) + goto out; + r = kvm_irqfd(kvm, data.fd, data.gsi, data.flags); + break; + } default: r = kvm_arch_vm_ioctl(filp, ioctl, arg); } |