1 files changed, 578 insertions, 0 deletions

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
new file mode 100644
index 000000000000..bb4ebd89b9ff
--- /dev/null
+++ b/virt/kvm/eventfd.c
@@ -0,0 +1,578 @@
+/*
+ * 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/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 "iodev.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->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);
+}
+
+/*
+ * 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 (!IS_ERR(file))
+                fput(file);
+
+        kfree(irqfd);
+        return ret;
+}
+
+void
+kvm_eventfd_init(struct kvm *kvm)
+{
+        spin_lock_init(&kvm->irqfds.lock);
+        INIT_LIST_HEAD(&kvm->irqfds.items);
+        INIT_LIST_HEAD(&kvm->ioeventfds);
+}
+
+/*
+ * 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);
+
+/*
+ * --------------------------------------------------------------------
+ * 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;
+        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 && 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_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->addr == p->addr && _p->length == p->length &&
+                    (_p->wildcard || p->wildcard ||
+                     _p->datamatch == p->datamatch))
+                        return true;
+
+        return false;
+}
+
+static int
+kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
+{
+        int                       pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
+        struct kvm_io_bus        *bus = pio ? &kvm->pio_bus : &kvm->mmio_bus;
+        struct _ioeventfd        *p;
+        struct eventfd_ctx       *eventfd;
+        int                       ret;
+
+        /* must be natural-word sized */
+        switch (args->len) {
+        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;
+
+        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->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;
+
+        down_write(&kvm->slots_lock);
+
+        /* Verify that there isnt 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(bus, &p->dev);
+        if (ret < 0)
+                goto unlock_fail;
+
+        list_add_tail(&p->list, &kvm->ioeventfds);
+
+        up_write(&kvm->slots_lock);
+
+        return 0;
+
+unlock_fail:
+        up_write(&kvm->slots_lock);
+
+fail:
+        kfree(p);
+        eventfd_ctx_put(eventfd);
+
+        return ret;
+}
+
+static int
+kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
+{
+        int                       pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
+        struct kvm_io_bus        *bus = pio ? &kvm->pio_bus : &kvm->mmio_bus;
+        struct _ioeventfd        *p, *tmp;
+        struct eventfd_ctx       *eventfd;
+        int                       ret = -ENOENT;
+
+        eventfd = eventfd_ctx_fdget(args->fd);
+        if (IS_ERR(eventfd))
+                return PTR_ERR(eventfd);
+
+        down_write(&kvm->slots_lock);
+
+        list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
+                bool wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
+
+                if (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(bus, &p->dev);
+                ioeventfd_release(p);
+                ret = 0;
+                break;
+        }
+
+        up_write(&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);
+}