/*
 * VFIO PCI interrupt handling
 *
 * Copyright (C) 2012 Red Hat, Inc.  All rights reserved.
 *     Author: Alex Williamson <alex.williamson@redhat.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Derived from original vfio:
 * Copyright 2010 Cisco Systems, Inc.  All rights reserved.
 * Author: Tom Lyon, pugs@cisco.com
 */

#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/eventfd.h>
#include <linux/pci.h>
#include <linux/file.h>
#include <linux/poll.h>
#include <linux/vfio.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
#include <linux/slab.h>

#include "vfio_pci_private.h"

/*
 * IRQfd - generic
 */
struct virqfd {
        struct vfio_pci_device  *vdev;
        struct eventfd_ctx      *eventfd;
        int                     (*handler)(struct vfio_pci_device *, void *);
        void                    (*thread)(struct vfio_pci_device *, void *);
        void                    *data;
        struct work_struct      inject;
        wait_queue_t            wait;
        poll_table              pt;
        struct work_struct      shutdown;
        struct virqfd           **pvirqfd;
};

static struct workqueue_struct *vfio_irqfd_cleanup_wq;

int __init vfio_pci_virqfd_init(void)
{
        vfio_irqfd_cleanup_wq =
                create_singlethread_workqueue("vfio-irqfd-cleanup");
        if (!vfio_irqfd_cleanup_wq)
                return -ENOMEM;

        return 0;
}

void vfio_pci_virqfd_exit(void)
{
        destroy_workqueue(vfio_irqfd_cleanup_wq);
}

static void virqfd_deactivate(struct virqfd *virqfd)
{
        queue_work(vfio_irqfd_cleanup_wq, &virqfd->shutdown);
}

static int virqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key)
{
        struct virqfd *virqfd = container_of(wait, struct virqfd, wait);
        unsigned long flags = (unsigned long)key;

        if (flags & POLLIN) {
                /* An event has been signaled, call function */
                if ((!virqfd->handler ||
                     virqfd->handler(virqfd->vdev, virqfd->data)) &&
                    virqfd->thread)
                        schedule_work(&virqfd->inject);
        }

        if (flags & POLLHUP) {
                unsigned long flags;
                spin_lock_irqsave(&virqfd->vdev->irqlock, flags);

                /*
                 * The eventfd is closing, if the virqfd has not yet been
                 * queued for release, as determined by testing whether the
                 * vdev pointer to it is still valid, queue it now.  As
                 * with kvm irqfds, we know we won't race against the virqfd
                 * going away because we hold wqh->lock to get here.
                 */
                if (*(virqfd->pvirqfd) == virqfd) {
                        *(virqfd->pvirqfd) = NULL;
                        virqfd_deactivate(virqfd);
                }

                spin_unlock_irqrestore(&virqfd->vdev->irqlock, flags);
        }

        return 0;
}

static void virqfd_ptable_queue_proc(struct file *file,
                                     wait_queue_head_t *wqh, poll_table *pt)
{
        struct virqfd *virqfd = container_of(pt, struct virqfd, pt);
        add_wait_queue(wqh, &virqfd->wait);
}

static void virqfd_shutdown(struct work_struct *work)
{
        struct virqfd *virqfd = container_of(work, struct virqfd, shutdown);
        u64 cnt;

        eventfd_ctx_remove_wait_queue(virqfd->eventfd, &virqfd->wait, &cnt);
        flush_work(&virqfd->inject);
        eventfd_ctx_put(virqfd->eventfd);

        kfree(virqfd);
}

static void virqfd_inject(struct work_struct *work)
{
        struct virqfd *virqfd = container_of(work, struct virqfd, inject);
        if (virqfd->thread)
                virqfd->thread(virqfd->vdev, virqfd->data);
}

static int virqfd_enable(struct vfio_pci_device *vdev,
                         int (*handler)(struct vfio_pci_device *, void *),
                         void (*thread)(struct vfio_pci_device *, void *),
                         void *data, struct virqfd **pvirqfd, int fd)
{
        struct fd irqfd;
        struct eventfd_ctx *ctx;
        struct virqfd *virqfd;
        int ret = 0;
        unsigned int events;

        virqfd = kzalloc(sizeof(*virqfd), GFP_KERNEL);
        if (!virqfd)
                return -ENOMEM;

        virqfd->pvirqfd = pvirqfd;
        virqfd->vdev = vdev;
        virqfd->handler = handler;
        virqfd->thread = thread;
        virqfd->data = data;

        INIT_WORK(&virqfd->shutdown, virqfd_shutdown);
        INIT_WORK(&virqfd->inject, virqfd_inject);

        irqfd = fdget(fd);
        if (!irqfd.file) {
                ret = -EBADF;
                goto err_fd;
        }

        ctx = eventfd_ctx_fileget(irqfd.file);
        if (IS_ERR(ctx)) {
                ret = PTR_ERR(ctx);
                goto err_ctx;
        }

        virqfd->eventfd = ctx;

        /*
         * virqfds can be released by closing the eventfd or directly
         * through ioctl.  These are both done through a workqueue, so
         * we update the pointer to the virqfd under lock to avoid
         * pushing multiple jobs to release the same virqfd.
         */
        spin_lock_irq(&vdev->irqlock);

        if (*pvirqfd) {
                spin_unlock_irq(&vdev->irqlock);
                ret = -EBUSY;
                goto err_busy;
        }
        *pvirqfd = virqfd;

        spin_unlock_irq(&vdev->irqlock);

        /*
         * Install our own custom wake-up handling so we are notified via
         * a callback whenever someone signals the underlying eventfd.
         */
        init_waitqueue_func_entry(&virqfd->wait, virqfd_wakeup);
        init_poll_funcptr(&virqfd->pt, virqfd_ptable_queue_proc);

        events = irqfd.file->f_op->poll(irqfd.file, &virqfd->pt);

        /*
         * 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) {
                if ((!handler || handler(vdev, data)) && thread)
                        schedule_work(&virqfd->inject);
        }

        /*
         * Do not drop the file until the irqfd is fully initialized,
         * otherwise we might race against the POLLHUP.
         */
        fdput(irqfd);

        return 0;
err_busy:
        eventfd_ctx_put(ctx);
err_ctx:
        fdput(irqfd);
err_fd:
        kfree(virqfd);

        return ret;
}

static void virqfd_disable(struct vfio_pci_device *vdev,
                           struct virqfd **pvirqfd)
{
        unsigned long flags;

        spin_lock_irqsave(&vdev->irqlock, flags);

        if (*pvirqfd) {
                virqfd_deactivate(*pvirqfd);
                *pvirqfd = NULL;
        }

        spin_unlock_irqrestore(&vdev->irqlock, flags);

        /*
         * Block until we know all outstanding shutdown jobs have completed.
         * Even if we don't queue the job, flush the wq to be sure it's
         * been released.
         */
        flush_workqueue(vfio_irqfd_cleanup_wq);
}

/*
 * INTx
 */
static void vfio_send_intx_eventfd(struct vfio_pci_device *vdev, void *unused)
{
        if (likely(is_intx(vdev) && !vdev->virq_disabled))
                eventfd_signal(vdev->ctx[0].trigger, 1);
}

void vfio_pci_intx_mask(struct vfio_pci_device *vdev)
{
        struct pci_dev *pdev = vdev->pdev;
        unsigned long flags;

        spin_lock_irqsave(&vdev->irqlock, flags);

        /*
         * Masking can come from interrupt, ioctl, or config space
         * via INTx disable.  The latter means this can get called
         * even when not using intx delivery.  In this case, just
         * try to have the physical bit follow the virtual bit.
         */
        if (unlikely(!is_intx(vdev))) {
                if (vdev->pci_2_3)
                        pci_intx(pdev, 0);
        } else if (!vdev->ctx[0].masked) {
                /*
                 * Can't use check_and_mask here because we always want to
                 * mask, not just when something is pending.
                 */
                if (vdev->pci_2_3)
                        pci_intx(pdev, 0);
                else
                        disable_irq_nosync(pdev->irq);

                vdev->ctx[0].masked = true;
        }

        spin_unlock_irqrestore(&vdev->irqlock, flags);
}

/*
 * If this is triggered by an eventfd, we can't call eventfd_signal
 * or else we'll deadlock on the eventfd wait queue.  Return >0 when
 * a signal is necessary, which can then be handled via a work queue
 * or directly depending on the caller.
 */
static int vfio_pci_intx_unmask_handler(struct vfio_pci_device *vdev,
                                        void *unused)
{
        struct pci_dev *pdev = vdev->pdev;
        unsigned long flags;
        int ret = 0;

        spin_lock_irqsave(&vdev->irqlock, flags);

        /*
         * Unmasking comes from ioctl or config, so again, have the
         * physical bit follow the virtual even when not using INTx.
         */
        if (unlikely(!is_intx(vdev))) {
                if (vdev->pci_2_3)
                        pci_intx(pdev, 1);
        } else if (vdev->ctx[0].masked && !vdev->virq_disabled) {
                /*
                 * A pending interrupt here would immediately trigger,
                 * but we can avoid that overhead by just re-sending
                 * the interrupt to the user.
                 */
                if (vdev->pci_2_3) {
                        if (!pci_check_and_unmask_intx(pdev))
                                ret = 1;
                } else
                        enable_irq(pdev->irq);

                vdev->ctx[0].masked = (ret > 0);
        }

        spin_unlock_irqrestore(&vdev->irqlock, flags);

        return ret;
}

void vfio_pci_intx_unmask(struct vfio_pci_device *vdev)
{
        if (vfio_pci_intx_unmask_handler(vdev, NULL) > 0)
                vfio_send_intx_eventfd(vdev, NULL);
}

static irqreturn_t vfio_intx_handler(int irq, void *dev_id)
{
        struct vfio_pci_device *vdev = dev_id;
        unsigned long flags;
        int ret = IRQ_NONE;

        spin_lock_irqsave(&vdev->irqlock, flags);

        if (!vdev->pci_2_3) {
                disable_irq_nosync(vdev->pdev->irq);
                vdev->ctx[0].masked = true;
                ret = IRQ_HANDLED;
        } else if (!vdev->ctx[0].masked &&  /* may be shared */
                   pci_check_and_mask_intx(vdev->pdev)) {
                vdev->ctx[0].masked = true;
                ret = IRQ_HANDLED;
        }

        spin_unlock_irqrestore(&vdev->irqlock, flags);

        if (ret == IRQ_HANDLED)
                vfio_send_intx_eventfd(vdev, NULL);

        return ret;
}

static int vfio_intx_enable(struct vfio_pci_device *vdev)
{
        if (!is_irq_none(vdev))
                return -EINVAL;

        if (!vdev->pdev->irq)
                return -ENODEV;

        vdev->ctx = kzalloc(sizeof(struct vfio_pci_irq_ctx), GFP_KERNEL);
        if (!vdev->ctx)
                return -ENOMEM;

        vdev->num_ctx = 1;

        /*
         * If the virtual interrupt is masked, restore it.  Devices
         * supporting DisINTx can be masked at the hardware level
         * here, non-PCI-2.3 devices will have to wait until the
         * interrupt is enabled.
         */
        vdev->ctx[0].masked = vdev->virq_disabled;
        if (vdev->pci_2_3)
                pci_intx(vdev->pdev, !vdev->ctx[0].masked);

        vdev->irq_type = VFIO_PCI_INTX_IRQ_INDEX;

        return 0;
}

static int vfio_intx_set_signal(struct vfio_pci_device *vdev, int fd)
{
        struct pci_dev *pdev = vdev->pdev;
        unsigned long irqflags = IRQF_SHARED;
        struct eventfd_ctx *trigger;
        unsigned long flags;
        int ret;

        if (vdev->ctx[0].trigger) {
                free_irq(pdev->irq, vdev);
                kfree(vdev->ctx[0].name);
                eventfd_ctx_put(vdev->ctx[0].trigger);
                vdev->ctx[0].trigger = NULL;
        }

        if (fd < 0) /* Disable only */
                return 0;

        vdev->ctx[0].name = kasprintf(GFP_KERNEL, "vfio-intx(%s)",
                                      pci_name(pdev));
        if (!vdev->ctx[0].name)
                return -ENOMEM;

        trigger = eventfd_ctx_fdget(fd);
        if (IS_ERR(trigger)) {
                kfree(vdev->ctx[0].name);
                return PTR_ERR(trigger);
        }

        vdev->ctx[0].trigger = trigger;

        if (!vdev->pci_2_3)
                irqflags = 0;

        ret = request_irq(pdev->irq, vfio_intx_handler,
                          irqflags, vdev->ctx[0].name, vdev);
        if (ret) {
                vdev->ctx[0].trigger = NULL;
                kfree(vdev->ctx[0].name);
                eventfd_ctx_put(trigger);
                return ret;
        }

        /*
         * INTx disable will stick across the new irq setup,
         * disable_irq won't.
         */
        spin_lock_irqsave(&vdev->irqlock, flags);
        if (!vdev->pci_2_3 && vdev->ctx[0].masked)
                disable_irq_nosync(pdev->irq);
        spin_unlock_irqrestore(&vdev->irqlock, flags);

        return 0;
}

static void vfio_intx_disable(struct vfio_pci_device *vdev)
{
        vfio_intx_set_signal(vdev, -1);
        virqfd_disable(vdev, &vdev->ctx[0].unmask);
        virqfd_disable(vdev, &vdev->ctx[0].mask);
        vdev->irq_type = VFIO_PCI_NUM_IRQS;
        vdev->num_ctx = 0;
        kfree(vdev->ctx);
}

/*
 * MSI/MSI-X
 */
static irqreturn_t vfio_msihandler(int irq, void *arg)
{
        struct eventfd_ctx *trigger = arg;

        eventfd_signal(trigger, 1);
        return IRQ_HANDLED;
}

static int vfio_msi_enable(struct vfio_pci_device *vdev, int nvec, bool msix)
{
        struct pci_dev *pdev = vdev->pdev;
        int ret;

        if (!is_irq_none(vdev))
                return -EINVAL;

        vdev->ctx = kzalloc(nvec * sizeof(struct vfio_pci_irq_ctx), GFP_KERNEL);
        if (!vdev->ctx)
                return -ENOMEM;

        if (msix) {
                int i;

                vdev->msix = kzalloc(nvec * sizeof(struct msix_entry),
                                     GFP_KERNEL);
                if (!vdev->msix) {
                        kfree(vdev->ctx);
                        return -ENOMEM;
                }

                for (i = 0; i < nvec; i++)
                        vdev->msix[i].entry = i;

                ret = pci_enable_msix(pdev, vdev->msix, nvec);
                if (ret) {
                        kfree(vdev->msix);
                        kfree(vdev->ctx);
                        return ret;
                }
        } else {
                ret = pci_enable_msi_block(pdev, nvec);
                if (ret) {
                        kfree(vdev->ctx);
                        return ret;
                }
        }

        vdev->num_ctx = nvec;
        vdev->irq_type = msix ? VFIO_PCI_MSIX_IRQ_INDEX :
                                VFIO_PCI_MSI_IRQ_INDEX;

        if (!msix) {
                /*
                 * Compute the virtual hardware field for max msi vectors -
                 * it is the log base 2 of the number of vectors.
                 */
                vdev->msi_qmax = fls(nvec * 2 - 1) - 1;
        }

        return 0;
}

static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
                                      int vector, int fd, bool msix)
{
        struct pci_dev *pdev = vdev->pdev;
        int irq = msix ? vdev->msix[vector].vector : pdev->irq + vector;
        char *name = msix ? "vfio-msix" : "vfio-msi";
        struct eventfd_ctx *trigger;
        int ret;

        if (vector >= vdev->num_ctx)
                return -EINVAL;

        if (vdev->ctx[vector].trigger) {
                free_irq(irq, vdev->ctx[vector].trigger);
                kfree(vdev->ctx[vector].name);
                eventfd_ctx_put(vdev->ctx[vector].trigger);
                vdev->ctx[vector].trigger = NULL;
        }

        if (fd < 0)
                return 0;

        vdev->ctx[vector].name = kasprintf(GFP_KERNEL, "%s[%d](%s)",
                                           name, vector, pci_name(pdev));
        if (!vdev->ctx[vector].name)
                return -ENOMEM;

        trigger = eventfd_ctx_fdget(fd);
        if (IS_ERR(trigger)) {
                kfree(vdev->ctx[vector].name);
                return PTR_ERR(trigger);
        }

        ret = request_irq(irq, vfio_msihandler, 0,
                          vdev->ctx[vector].name, trigger);
        if (ret) {
                kfree(vdev->ctx[vector].name);
                eventfd_ctx_put(trigger);
                return ret;
        }

        vdev->ctx[vector].trigger = trigger;

        return 0;
}

static int vfio_msi_set_block(struct vfio_pci_device *vdev, unsigned start,
                              unsigned count, int32_t *fds, bool msix)
{
        int i, j, ret = 0;

        if (start + count > vdev->num_ctx)
                return -EINVAL;

        for (i = 0, j = start; i < count && !ret; i++, j++) {
                int fd = fds ? fds[i] : -1;
                ret = vfio_msi_set_vector_signal(vdev, j, fd, msix);
        }

        if (ret) {
                for (--j; j >= start; j--)
                        vfio_msi_set_vector_signal(vdev, j, -1, msix);
        }

        return ret;
}

static void vfio_msi_disable(struct vfio_pci_device *vdev, bool msix)
{
        struct pci_dev *pdev = vdev->pdev;
        int i;

        vfio_msi_set_block(vdev, 0, vdev->num_ctx, NULL, msix);

        for (i = 0; i < vdev->num_ctx; i++) {
                virqfd_disable(vdev, &vdev->ctx[i].unmask);
                virqfd_disable(vdev, &vdev->ctx[i].mask);
        }

        if (msix) {
                pci_disable_msix(vdev->pdev);
                kfree(vdev->msix);
        } else
                pci_disable_msi(pdev);

        vdev->irq_type = VFIO_PCI_NUM_IRQS;
        vdev->num_ctx = 0;
        kfree(vdev->ctx);
}

/*
 * IOCTL support
 */
static int vfio_pci_set_intx_unmask(struct vfio_pci_device *vdev,
                                    unsigned index, unsigned start,
                                    unsigned count, uint32_t flags, void *data)
{
        if (!is_intx(vdev) || start != 0 || count != 1)
                return -EINVAL;

        if (flags & VFIO_IRQ_SET_DATA_NONE) {
                vfio_pci_intx_unmask(vdev);
        } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
                uint8_t unmask = *(uint8_t *)data;
                if (unmask)
                        vfio_pci_intx_unmask(vdev);
        } else if (flags & VFIO_IRQ_SET_DATA_EVENTFD) {
                int32_t fd = *(int32_t *)data;
                if (fd >= 0)
                        return virqfd_enable(vdev, vfio_pci_intx_unmask_handler,
                                             vfio_send_intx_eventfd, NULL,
                                             &vdev->ctx[0].unmask, fd);

                virqfd_disable(vdev, &vdev->ctx[0].unmask);
        }

        return 0;
}

static int vfio_pci_set_intx_mask(struct vfio_pci_device *vdev,
                                  unsigned index, unsigned start,
                                  unsigned count, uint32_t flags, void *data)
{
        if (!is_intx(vdev) || start != 0 || count != 1)
                return -EINVAL;

        if (flags & VFIO_IRQ_SET_DATA_NONE) {
                vfio_pci_intx_mask(vdev);
        } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
                uint8_t mask = *(uint8_t *)data;
                if (mask)
                        vfio_pci_intx_mask(vdev);
        } else if (flags & VFIO_IRQ_SET_DATA_EVENTFD) {
                return -ENOTTY; /* XXX implement me */
        }

        return 0;
}

static int vfio_pci_set_intx_trigger(struct vfio_pci_device *vdev,
                                     unsigned index, unsigned start,
                                     unsigned count, uint32_t flags, void *data)
{
        if (is_intx(vdev) && !count && (flags & VFIO_IRQ_SET_DATA_NONE)) {
                vfio_intx_disable(vdev);
                return 0;
        }

        if (!(is_intx(vdev) || is_irq_none(vdev)) || start != 0 || count != 1)
                return -EINVAL;

        if (flags & VFIO_IRQ_SET_DATA_EVENTFD) {
                int32_t fd = *(int32_t *)data;
                int ret;

                if (is_intx(vdev))
                        return vfio_intx_set_signal(vdev, fd);

                ret = vfio_intx_enable(vdev);
                if (ret)
                        return ret;

                ret = vfio_intx_set_signal(vdev, fd);
                if (ret)
                        vfio_intx_disable(vdev);

                return ret;
        }

        if (!is_intx(vdev))
                return -EINVAL;

        if (flags & VFIO_IRQ_SET_DATA_NONE) {
                vfio_send_intx_eventfd(vdev, NULL);
        } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
                uint8_t trigger = *(uint8_t *)data;
                if (trigger)
                        vfio_send_intx_eventfd(vdev, NULL);
        }
        return 0;
}

static int vfio_pci_set_msi_trigger(struct vfio_pci_device *vdev,
                                    unsigned index, unsigned start,
                                    unsigned count, uint32_t flags, void *data)
{
        int i;
        bool msix = (index == VFIO_PCI_MSIX_IRQ_INDEX) ? true : false;

        if (irq_is(vdev, index) && !count && (flags & VFIO_IRQ_SET_DATA_NONE)) {
                vfio_msi_disable(vdev, msix);
                return 0;
        }

        if (!(irq_is(vdev, index) || is_irq_none(vdev)))
                return -EINVAL;

        if (flags & VFIO_IRQ_SET_DATA_EVENTFD) {
                int32_t *fds = data;
                int ret;

                if (vdev->irq_type == index)
                        return vfio_msi_set_block(vdev, start, count,
                                                  fds, msix);

                ret = vfio_msi_enable(vdev, start + count, msix);
                if (ret)
                        return ret;

                ret = vfio_msi_set_block(vdev, start, count, fds, msix);
                if (ret)
                        vfio_msi_disable(vdev, msix);

                return ret;
        }

        if (!irq_is(vdev, index) || start + count > vdev->num_ctx)
                return -EINVAL;

        for (i = start; i < start + count; i++) {
                if (!vdev->ctx[i].trigger)
                        continue;
                if (flags & VFIO_IRQ_SET_DATA_NONE) {
                        eventfd_signal(vdev->ctx[i].trigger, 1);
                } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
                        uint8_t *bools = data;
                        if (bools[i - start])
                                eventfd_signal(vdev->ctx[i].trigger, 1);
                }
        }
        return 0;
}

static int vfio_pci_set_err_trigger(struct vfio_pci_device *vdev,
                                    unsigned index, unsigned start,
                                    unsigned count, uint32_t flags, void *data)
{
        int32_t fd = *(int32_t *)data;
        struct pci_dev *pdev = vdev->pdev;

        if ((index != VFIO_PCI_ERR_IRQ_INDEX) ||
            !(flags & VFIO_IRQ_SET_DATA_TYPE_MASK))
                return -EINVAL;

        /*
         * device_lock synchronizes setting and checking of
         * err_trigger. The vfio_pci_aer_err_detected() is also
         * called with device_lock held.
         */

        /* DATA_NONE/DATA_BOOL enables loopback testing */

        if (flags & VFIO_IRQ_SET_DATA_NONE) {
                device_lock(&pdev->dev);
                if (vdev->err_trigger)
                        eventfd_signal(vdev->err_trigger, 1);
                device_unlock(&pdev->dev);
                return 0;
        } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
                uint8_t trigger = *(uint8_t *)data;
                device_lock(&pdev->dev);
                if (trigger && vdev->err_trigger)
                        eventfd_signal(vdev->err_trigger, 1);
                device_unlock(&pdev->dev);
                return 0;
        }

        /* Handle SET_DATA_EVENTFD */

        if (fd == -1) {
                device_lock(&pdev->dev);
                if (vdev->err_trigger)
                        eventfd_ctx_put(vdev->err_trigger);
                vdev->err_trigger = NULL;
                device_unlock(&pdev->dev);
                return 0;
        } else if (fd >= 0) {
                struct eventfd_ctx *efdctx;
                efdctx = eventfd_ctx_fdget(fd);
                if (IS_ERR(efdctx))
                        return PTR_ERR(efdctx);
                device_lock(&pdev->dev);
                if (vdev->err_trigger)
                        eventfd_ctx_put(vdev->err_trigger);
                vdev->err_trigger = efdctx;
                device_unlock(&pdev->dev);
                return 0;
        } else
                return -EINVAL;
}
int vfio_pci_set_irqs_ioctl(struct vfio_pci_device *vdev, uint32_t flags,
                            unsigned index, unsigned start, unsigned count,
                            void *data)
{
        int (*func)(struct vfio_pci_device *vdev, unsigned index,
                    unsigned start, unsigned count, uint32_t flags,
                    void *data) = NULL;

        switch (index) {
        case VFIO_PCI_INTX_IRQ_INDEX:
                switch (flags & VFIO_IRQ_SET_ACTION_TYPE_MASK) {
                case VFIO_IRQ_SET_ACTION_MASK:
                        func = vfio_pci_set_intx_mask;
                        break;
                case VFIO_IRQ_SET_ACTION_UNMASK:
                        func = vfio_pci_set_intx_unmask;
                        break;
                case VFIO_IRQ_SET_ACTION_TRIGGER:
                        func = vfio_pci_set_intx_trigger;
                        break;
                }
                break;
        case VFIO_PCI_MSI_IRQ_INDEX:
        case VFIO_PCI_MSIX_IRQ_INDEX:
                switch (flags & VFIO_IRQ_SET_ACTION_TYPE_MASK) {
                case VFIO_IRQ_SET_ACTION_MASK:
                case VFIO_IRQ_SET_ACTION_UNMASK:
                        /* XXX Need masking support exported */
                        break;
                case VFIO_IRQ_SET_ACTION_TRIGGER:
                        func = vfio_pci_set_msi_trigger;
                        break;
                }
                break;
        case VFIO_PCI_ERR_IRQ_INDEX:
                switch (flags & VFIO_IRQ_SET_ACTION_TYPE_MASK) {
                case VFIO_IRQ_SET_ACTION_TRIGGER:
                        if (pci_is_pcie(vdev->pdev))
                                func = vfio_pci_set_err_trigger;
                        break;
                }
        }

        if (!func)
                return -ENOTTY;

        return func(vdev, index, start, count, flags, data);
}