/*
 * Xen event channels
 *
 * Xen models interrupts with abstract event channels.  Because each
 * domain gets 1024 event channels, but NR_IRQ is not that large, we
 * must dynamically map irqs<->event channels.  The event channels
 * interface with the rest of the kernel by defining a xen interrupt
 * chip.  When an event is received, it is mapped to an irq and sent
 * through the normal interrupt processing path.
 *
 * There are four kinds of events which can be mapped to an event
 * channel:
 *
 * 1. Inter-domain notifications.  This includes all the virtual
 *    device events, since they're driven by front-ends in another domain
 *    (typically dom0).
 * 2. VIRQs, typically used for timers.  These are per-cpu events.
 * 3. IPIs.
 * 4. PIRQs - Hardware interrupts.
 *
 * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
 */

#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt

#include <linux/linkage.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/moduleparam.h>
#include <linux/string.h>
#include <linux/bootmem.h>
#include <linux/slab.h>
#include <linux/irqnr.h>
#include <linux/pci.h>

#ifdef CONFIG_X86
#include <asm/desc.h>
#include <asm/ptrace.h>
#include <asm/irq.h>
#include <asm/io_apic.h>
#include <asm/i8259.h>
#include <asm/xen/pci.h>
#endif
#include <asm/sync_bitops.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>
#include <xen/page.h>

#include <xen/xen.h>
#include <xen/hvm.h>
#include <xen/xen-ops.h>
#include <xen/events.h>
#include <xen/interface/xen.h>
#include <xen/interface/event_channel.h>
#include <xen/interface/hvm/hvm_op.h>
#include <xen/interface/hvm/params.h>
#include <xen/interface/physdev.h>
#include <xen/interface/sched.h>
#include <xen/interface/vcpu.h>
#include <asm/hw_irq.h>

#include "events_internal.h"

const struct evtchn_ops *evtchn_ops;

/*
 * This lock protects updates to the following mapping and reference-count
 * arrays. The lock does not need to be acquired to read the mapping tables.
 */
static DEFINE_MUTEX(irq_mapping_update_lock);

static LIST_HEAD(xen_irq_list_head);

/* IRQ <-> VIRQ mapping. */
static DEFINE_PER_CPU(int [NR_VIRQS], virq_to_irq) = {[0 ... NR_VIRQS-1] = -1};

/* IRQ <-> IPI mapping */
static DEFINE_PER_CPU(int [XEN_NR_IPIS], ipi_to_irq) = {[0 ... XEN_NR_IPIS-1] = -1};

int **evtchn_to_irq;
#ifdef CONFIG_X86
static unsigned long *pirq_eoi_map;
#endif
static bool (*pirq_needs_eoi)(unsigned irq);

#define EVTCHN_ROW(e)  (e / (PAGE_SIZE/sizeof(**evtchn_to_irq)))
#define EVTCHN_COL(e)  (e % (PAGE_SIZE/sizeof(**evtchn_to_irq)))
#define EVTCHN_PER_ROW (PAGE_SIZE / sizeof(**evtchn_to_irq))

/* Xen will never allocate port zero for any purpose. */
#define VALID_EVTCHN(chn)       ((chn) != 0)

static struct irq_chip xen_dynamic_chip;
static struct irq_chip xen_percpu_chip;
static struct irq_chip xen_pirq_chip;
static void enable_dynirq(struct irq_data *data);
static void disable_dynirq(struct irq_data *data);

static void clear_evtchn_to_irq_row(unsigned row)
{
        unsigned col;

        for (col = 0; col < EVTCHN_PER_ROW; col++)
                evtchn_to_irq[row][col] = -1;
}

static void clear_evtchn_to_irq_all(void)
{
        unsigned row;

        for (row = 0; row < EVTCHN_ROW(xen_evtchn_max_channels()); row++) {
                if (evtchn_to_irq[row] == NULL)
                        continue;
                clear_evtchn_to_irq_row(row);
        }
}

static int set_evtchn_to_irq(unsigned evtchn, unsigned irq)
{
        unsigned row;
        unsigned col;

        if (evtchn >= xen_evtchn_max_channels())
                return -EINVAL;

        row = EVTCHN_ROW(evtchn);
        col = EVTCHN_COL(evtchn);

        if (evtchn_to_irq[row] == NULL) {
                /* Unallocated irq entries return -1 anyway */
                if (irq == -1)
                        return 0;

                evtchn_to_irq[row] = (int *)get_zeroed_page(GFP_KERNEL);
                if (evtchn_to_irq[row] == NULL)
                        return -ENOMEM;

                clear_evtchn_to_irq_row(row);
        }

        evtchn_to_irq[EVTCHN_ROW(evtchn)][EVTCHN_COL(evtchn)] = irq;
        return 0;
}

int get_evtchn_to_irq(unsigned evtchn)
{
        if (evtchn >= xen_evtchn_max_channels())
                return -1;
        if (evtchn_to_irq[EVTCHN_ROW(evtchn)] == NULL)
                return -1;
        return evtchn_to_irq[EVTCHN_ROW(evtchn)][EVTCHN_COL(evtchn)];
}

/* Get info for IRQ */
struct irq_info *info_for_irq(unsigned irq)
{
        return irq_get_handler_data(irq);
}

/* Constructors for packed IRQ information. */
static int xen_irq_info_common_setup(struct irq_info *info,
                                     unsigned irq,
                                     enum xen_irq_type type,
                                     unsigned evtchn,
                                     unsigned short cpu)
{
        int ret;

        BUG_ON(info->type != IRQT_UNBOUND && info->type != type);

        info->type = type;
        info->irq = irq;
        info->evtchn = evtchn;
        info->cpu = cpu;

        ret = set_evtchn_to_irq(evtchn, irq);
        if (ret < 0)
                return ret;

        irq_clear_status_flags(irq, IRQ_NOREQUEST|IRQ_NOAUTOEN);

        return xen_evtchn_port_setup(info);
}

static int xen_irq_info_evtchn_setup(unsigned irq,
                                     unsigned evtchn)
{
        struct irq_info *info = info_for_irq(irq);

        return xen_irq_info_common_setup(info, irq, IRQT_EVTCHN, evtchn, 0);
}

static int xen_irq_info_ipi_setup(unsigned cpu,
                                  unsigned irq,
                                  unsigned evtchn,
                                  enum ipi_vector ipi)
{
        struct irq_info *info = info_for_irq(irq);

        info->u.ipi = ipi;

        per_cpu(ipi_to_irq, cpu)[ipi] = irq;

        return xen_irq_info_common_setup(info, irq, IRQT_IPI, evtchn, 0);
}

static int xen_irq_info_virq_setup(unsigned cpu,
                                   unsigned irq,
                                   unsigned evtchn,
                                   unsigned virq)
{
        struct irq_info *info = info_for_irq(irq);

        info->u.virq = virq;

        per_cpu(virq_to_irq, cpu)[virq] = irq;

        return xen_irq_info_common_setup(info, irq, IRQT_VIRQ, evtchn, 0);
}

static int xen_irq_info_pirq_setup(unsigned irq,
                                   unsigned evtchn,
                                   unsigned pirq,
                                   unsigned gsi,
                                   uint16_t domid,
                                   unsigned char flags)
{
        struct irq_info *info = info_for_irq(irq);

        info->u.pirq.pirq = pirq;
        info->u.pirq.gsi = gsi;
        info->u.pirq.domid = domid;
        info->u.pirq.flags = flags;

        return xen_irq_info_common_setup(info, irq, IRQT_PIRQ, evtchn, 0);
}

static void xen_irq_info_cleanup(struct irq_info *info)
{
        set_evtchn_to_irq(info->evtchn, -1);
        info->evtchn = 0;
}

/*
 * Accessors for packed IRQ information.
 */
unsigned int evtchn_from_irq(unsigned irq)
{
        if (unlikely(WARN(irq >= nr_irqs, "Invalid irq %d!\n", irq)))
                return 0;

        return info_for_irq(irq)->evtchn;
}

unsigned irq_from_evtchn(unsigned int evtchn)
{
        return get_evtchn_to_irq(evtchn);
}
EXPORT_SYMBOL_GPL(irq_from_evtchn);

int irq_from_virq(unsigned int cpu, unsigned int virq)
{
        return per_cpu(virq_to_irq, cpu)[virq];
}

static enum ipi_vector ipi_from_irq(unsigned irq)
{
        struct irq_info *info = info_for_irq(irq);

        BUG_ON(info == NULL);
        BUG_ON(info->type != IRQT_IPI);

        return info->u.ipi;
}

static unsigned virq_from_irq(unsigned irq)
{
        struct irq_info *info = info_for_irq(irq);

        BUG_ON(info == NULL);
        BUG_ON(info->type != IRQT_VIRQ);

        return info->u.virq;
}

static unsigned pirq_from_irq(unsigned irq)
{
        struct irq_info *info = info_for_irq(irq);

        BUG_ON(info == NULL);
        BUG_ON(info->type != IRQT_PIRQ);

        return info->u.pirq.pirq;
}

static enum xen_irq_type type_from_irq(unsigned irq)
{
        return info_for_irq(irq)->type;
}

unsigned cpu_from_irq(unsigned irq)
{
        return info_for_irq(irq)->cpu;
}

unsigned int cpu_from_evtchn(unsigned int evtchn)
{
        int irq = get_evtchn_to_irq(evtchn);
        unsigned ret = 0;

        if (irq != -1)
                ret = cpu_from_irq(irq);

        return ret;
}

#ifdef CONFIG_X86
static bool pirq_check_eoi_map(unsigned irq)
{
        return test_bit(pirq_from_irq(irq), pirq_eoi_map);
}
#endif

static bool pirq_needs_eoi_flag(unsigned irq)
{
        struct irq_info *info = info_for_irq(irq);
        BUG_ON(info->type != IRQT_PIRQ);

        return info->u.pirq.flags & PIRQ_NEEDS_EOI;
}

static void bind_evtchn_to_cpu(unsigned int chn, unsigned int cpu)
{
        int irq = get_evtchn_to_irq(chn);
        struct irq_info *info = info_for_irq(irq);

        BUG_ON(irq == -1);
#ifdef CONFIG_SMP
        cpumask_copy(irq_get_affinity_mask(irq), cpumask_of(cpu));
#endif
        xen_evtchn_port_bind_to_cpu(info, cpu);

        info->cpu = cpu;
}

/**
 * notify_remote_via_irq - send event to remote end of event channel via irq
 * @irq: irq of event channel to send event to
 *
 * Unlike notify_remote_via_evtchn(), this is safe to use across
 * save/restore. Notifications on a broken connection are silently
 * dropped.
 */
void notify_remote_via_irq(int irq)
{
        int evtchn = evtchn_from_irq(irq);

        if (VALID_EVTCHN(evtchn))
                notify_remote_via_evtchn(evtchn);
}
EXPORT_SYMBOL_GPL(notify_remote_via_irq);

static void xen_irq_init(unsigned irq)
{
        struct irq_info *info;
#ifdef CONFIG_SMP
        /* By default all event channels notify CPU#0. */
        cpumask_copy(irq_get_affinity_mask(irq), cpumask_of(0));
#endif

        info = kzalloc(sizeof(*info), GFP_KERNEL);
        if (info == NULL)
                panic("Unable to allocate metadata for IRQ%d\n", irq);

        info->type = IRQT_UNBOUND;
        info->refcnt = -1;

        irq_set_handler_data(irq, info);

        list_add_tail(&info->list, &xen_irq_list_head);
}

static int __must_check xen_allocate_irqs_dynamic(int nvec)
{
        int i, irq = irq_alloc_descs(-1, 0, nvec, -1);

        if (irq >= 0) {
                for (i = 0; i < nvec; i++)
                        xen_irq_init(irq + i);
        }

        return irq;
}

static inline int __must_check xen_allocate_irq_dynamic(void)
{

        return xen_allocate_irqs_dynamic(1);
}

static int __must_check xen_allocate_irq_gsi(unsigned gsi)
{
        int irq;

        /*
         * A PV guest has no concept of a GSI (since it has no ACPI
         * nor access to/knowledge of the physical APICs). Therefore
         * all IRQs are dynamically allocated from the entire IRQ
         * space.
         */
        if (xen_pv_domain() && !xen_initial_domain())
                return xen_allocate_irq_dynamic();

        /* Legacy IRQ descriptors are already allocated by the arch. */
        if (gsi < nr_legacy_irqs())
                irq = gsi;
        else
                irq = irq_alloc_desc_at(gsi, -1);

        xen_irq_init(irq);

        return irq;
}

static void xen_free_irq(unsigned irq)
{
        struct irq_info *info = irq_get_handler_data(irq);

        if (WARN_ON(!info))
                return;

        list_del(&info->list);

        irq_set_handler_data(irq, NULL);

        WARN_ON(info->refcnt > 0);

        kfree(info);

        /* Legacy IRQ descriptors are managed by the arch. */
        if (irq < nr_legacy_irqs())
                return;

        irq_free_desc(irq);
}

static void xen_evtchn_close(unsigned int port)
{
        struct evtchn_close close;

        close.port = port;
        if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
                BUG();
}

static void pirq_query_unmask(int irq)
{
        struct physdev_irq_status_query irq_status;
        struct irq_info *info = info_for_irq(irq);

        BUG_ON(info->type != IRQT_PIRQ);

        irq_status.irq = pirq_from_irq(irq);
        if (HYPERVISOR_physdev_op(PHYSDEVOP_irq_status_query, &irq_status))
                irq_status.flags = 0;

        info->u.pirq.flags &= ~PIRQ_NEEDS_EOI;
        if (irq_status.flags & XENIRQSTAT_needs_eoi)
                info->u.pirq.flags |= PIRQ_NEEDS_EOI;
}

static void eoi_pirq(struct irq_data *data)
{
        int evtchn = evtchn_from_irq(data->irq);
        struct physdev_eoi eoi = { .irq = pirq_from_irq(data->irq) };
        int rc = 0;

        if (!VALID_EVTCHN(evtchn))
                return;

        if (unlikely(irqd_is_setaffinity_pending(data)) &&
            likely(!irqd_irq_disabled(data))) {
                int masked = test_and_set_mask(evtchn);

                clear_evtchn(evtchn);

                irq_move_masked_irq(data);

                if (!masked)
                        unmask_evtchn(evtchn);
        } else
                clear_evtchn(evtchn);

        if (pirq_needs_eoi(data->irq)) {
                rc = HYPERVISOR_physdev_op(PHYSDEVOP_eoi, &eoi);
                WARN_ON(rc);
        }
}

static void mask_ack_pirq(struct irq_data *data)
{
        disable_dynirq(data);
        eoi_pirq(data);
}

static unsigned int __startup_pirq(unsigned int irq)
{
        struct evtchn_bind_pirq bind_pirq;
        struct irq_info *info = info_for_irq(irq);
        int evtchn = evtchn_from_irq(irq);
        int rc;

        BUG_ON(info->type != IRQT_PIRQ);

        if (VALID_EVTCHN(evtchn))
                goto out;

        bind_pirq.pirq = pirq_from_irq(irq);
        /* NB. We are happy to share unless we are probing. */
        bind_pirq.flags = info->u.pirq.flags & PIRQ_SHAREABLE ?
                                        BIND_PIRQ__WILL_SHARE : 0;
        rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_pirq, &bind_pirq);
        if (rc != 0) {
                pr_warn("Failed to obtain physical IRQ %d\n", irq);
                return 0;
        }
        evtchn = bind_pirq.port;

        pirq_query_unmask(irq);

        rc = set_evtchn_to_irq(evtchn, irq);
        if (rc)
                goto err;

        info->evtchn = evtchn;
        bind_evtchn_to_cpu(evtchn, 0);

        rc = xen_evtchn_port_setup(info);
        if (rc)
                goto err;

out:
        unmask_evtchn(evtchn);
        eoi_pirq(irq_get_irq_data(irq));

        return 0;

err:
        pr_err("irq%d: Failed to set port to irq mapping (%d)\n", irq, rc);
        xen_evtchn_close(evtchn);
        return 0;
}

static unsigned int startup_pirq(struct irq_data *data)
{
        return __startup_pirq(data->irq);
}

static void shutdown_pirq(struct irq_data *data)
{
        unsigned int irq = data->irq;
        struct irq_info *info = info_for_irq(irq);
        unsigned evtchn = evtchn_from_irq(irq);

        BUG_ON(info->type != IRQT_PIRQ);

        if (!VALID_EVTCHN(evtchn))
                return;

        mask_evtchn(evtchn);
        xen_evtchn_close(evtchn);
        xen_irq_info_cleanup(info);
}

static void enable_pirq(struct irq_data *data)
{
        enable_dynirq(data);
}

static void disable_pirq(struct irq_data *data)
{
        disable_dynirq(data);
}

int xen_irq_from_gsi(unsigned gsi)
{
        struct irq_info *info;

        list_for_each_entry(info, &xen_irq_list_head, list) {
                if (info->type != IRQT_PIRQ)
                        continue;

                if (info->u.pirq.gsi == gsi)
                        return info->irq;
        }

        return -1;
}
EXPORT_SYMBOL_GPL(xen_irq_from_gsi);

static void __unbind_from_irq(unsigned int irq)
{
        int evtchn = evtchn_from_irq(irq);
        struct irq_info *info = irq_get_handler_data(irq);

        if (info->refcnt > 0) {
                info->refcnt--;
                if (info->refcnt != 0)
                        return;
        }

        if (VALID_EVTCHN(evtchn)) {
                unsigned int cpu = cpu_from_irq(irq);

                xen_evtchn_close(evtchn);

                switch (type_from_irq(irq)) {
                case IRQT_VIRQ:
                        per_cpu(virq_to_irq, cpu)[virq_from_irq(irq)] = -1;
                        break;
                case IRQT_IPI:
                        per_cpu(ipi_to_irq, cpu)[ipi_from_irq(irq)] = -1;
                        break;
                default:
                        break;
                }

                xen_irq_info_cleanup(info);
        }

        BUG_ON(info_for_irq(irq)->type == IRQT_UNBOUND);

        xen_free_irq(irq);
}

/*
 * Do not make any assumptions regarding the relationship between the
 * IRQ number returned here and the Xen pirq argument.
 *
 * Note: We don't assign an event channel until the irq actually started
 * up.  Return an existing irq if we've already got one for the gsi.
 *
 * Shareable implies level triggered, not shareable implies edge
 * triggered here.
 */
int xen_bind_pirq_gsi_to_irq(unsigned gsi,
                             unsigned pirq, int shareable, char *name)
{
        int irq = -1;
        struct physdev_irq irq_op;
        int ret;

        mutex_lock(&irq_mapping_update_lock);

        irq = xen_irq_from_gsi(gsi);
        if (irq != -1) {
                pr_info("%s: returning irq %d for gsi %u\n",
                        __func__, irq, gsi);
                goto out;
        }

        irq = xen_allocate_irq_gsi(gsi);
        if (irq < 0)
                goto out;

        irq_op.irq = irq;
        irq_op.vector = 0;

        /* Only the privileged domain can do this. For non-priv, the pcifront
         * driver provides a PCI bus that does the call to do exactly
         * this in the priv domain. */
        if (xen_initial_domain() &&
            HYPERVISOR_physdev_op(PHYSDEVOP_alloc_irq_vector, &irq_op)) {
                xen_free_irq(irq);
                irq = -ENOSPC;
                goto out;
        }

        ret = xen_irq_info_pirq_setup(irq, 0, pirq, gsi, DOMID_SELF,
                               shareable ? PIRQ_SHAREABLE : 0);
        if (ret < 0) {
                __unbind_from_irq(irq);
                irq = ret;
                goto out;
        }

        pirq_query_unmask(irq);
        /* We try to use the handler with the appropriate semantic for the
         * type of interrupt: if the interrupt is an edge triggered
         * interrupt we use handle_edge_irq.
         *
         * On the other hand if the interrupt is level triggered we use
         * handle_fasteoi_irq like the native code does for this kind of
         * interrupts.
         *
         * Depending on the Xen version, pirq_needs_eoi might return true
         * not only for level triggered interrupts but for edge triggered
         * interrupts too. In any case Xen always honors the eoi mechanism,
         * not injecting any more pirqs of the same kind if the first one
         * hasn't received an eoi yet. Therefore using the fasteoi handler
         * is the right choice either way.
         */
        if (shareable)
                irq_set_chip_and_handler_name(irq, &xen_pirq_chip,
                                handle_fasteoi_irq, name);
        else
                irq_set_chip_and_handler_name(irq, &xen_pirq_chip,
                                handle_edge_irq, name);

out:
        mutex_unlock(&irq_mapping_update_lock);

        return irq;
}

#ifdef CONFIG_PCI_MSI
int xen_allocate_pirq_msi(struct pci_dev *dev, struct msi_desc *msidesc)
{
        int rc;
        struct physdev_get_free_pirq op_get_free_pirq;

        op_get_free_pirq.type = MAP_PIRQ_TYPE_MSI;
        rc = HYPERVISOR_physdev_op(PHYSDEVOP_get_free_pirq, &op_get_free_pirq);

        WARN_ONCE(rc == -ENOSYS,
                  "hypervisor does not support the PHYSDEVOP_get_free_pirq interface\n");

        return rc ? -1 : op_get_free_pirq.pirq;
}

int xen_bind_pirq_msi_to_irq(struct pci_dev *dev, struct msi_desc *msidesc,
                             int pirq, int nvec, const char *name, domid_t domid)
{
        int i, irq, ret;

        mutex_lock(&irq_mapping_update_lock);

        irq = xen_allocate_irqs_dynamic(nvec);
        if (irq < 0)
                goto out;

        for (i = 0; i < nvec; i++) {
                irq_set_chip_and_handler_name(irq + i, &xen_pirq_chip, handle_edge_irq, name);

                ret = xen_irq_info_pirq_setup(irq + i, 0, pirq + i, 0, domid,
                                              i == 0 ? 0 : PIRQ_MSI_GROUP);
                if (ret < 0)
                        goto error_irq;
        }

        ret = irq_set_msi_desc(irq, msidesc);
        if (ret < 0)
                goto error_irq;
out:
        mutex_unlock(&irq_mapping_update_lock);
        return irq;
error_irq:
        for (; i >= 0; i--)
                __unbind_from_irq(irq + i);
        mutex_unlock(&irq_mapping_update_lock);
        return ret;
}
#endif

int xen_destroy_irq(int irq)
{
        struct physdev_unmap_pirq unmap_irq;
        struct irq_info *info = info_for_irq(irq);
        int rc = -ENOENT;

        mutex_lock(&irq_mapping_update_lock);

        /*
         * If trying to remove a vector in a MSI group different
         * than the first one skip the PIRQ unmap unless this vector
         * is the first one in the group.
         */
        if (xen_initial_domain() && !(info->u.pirq.flags & PIRQ_MSI_GROUP)) {
                unmap_irq.pirq = info->u.pirq.pirq;
                unmap_irq.domid = info->u.pirq.domid;
                rc = HYPERVISOR_physdev_op(PHYSDEVOP_unmap_pirq, &unmap_irq);
                /* If another domain quits without making the pci_disable_msix
                 * call, the Xen hypervisor takes care of freeing the PIRQs
                 * (free_domain_pirqs).
                 */
                if ((rc == -ESRCH && info->u.pirq.domid != DOMID_SELF))
                        pr_info("domain %d does not have %d anymore\n",
                                info->u.pirq.domid, info->u.pirq.pirq);
                else if (rc) {
                        pr_warn("unmap irq failed %d\n", rc);
                        goto out;
                }
        }

        xen_free_irq(irq);

out:
        mutex_unlock(&irq_mapping_update_lock);
        return rc;
}

int xen_irq_from_pirq(unsigned pirq)
{
        int irq;

        struct irq_info *info;

        mutex_lock(&irq_mapping_update_lock);

        list_for_each_entry(info, &xen_irq_list_head, list) {
                if (info->type != IRQT_PIRQ)
                        continue;
                irq = info->irq;
                if (info->u.pirq.pirq == pirq)
                        goto out;
        }
        irq = -1;
out:
        mutex_unlock(&irq_mapping_update_lock);

        return irq;
}


int xen_pirq_from_irq(unsigned irq)
{
        return pirq_from_irq(irq);
}
EXPORT_SYMBOL_GPL(xen_pirq_from_irq);

int bind_evtchn_to_irq(unsigned int evtchn)
{
        int irq;
        int ret;

        if (evtchn >= xen_evtchn_max_channels())
                return -ENOMEM;

        mutex_lock(&irq_mapping_update_lock);

        irq = get_evtchn_to_irq(evtchn);

        if (irq == -1) {
                irq = xen_allocate_irq_dynamic();
                if (irq < 0)
                        goto out;

                irq_set_chip_and_handler_name(irq, &xen_dynamic_chip,
                                              handle_edge_irq, "event");

                ret = xen_irq_info_evtchn_setup(irq, evtchn);
                if (ret < 0) {
                        __unbind_from_irq(irq);
                        irq = ret;
                        goto out;
                }
                /* New interdomain events are bound to VCPU 0. */
                bind_evtchn_to_cpu(evtchn, 0);
        } else {
                struct irq_info *info = info_for_irq(irq);
                WARN_ON(info == NULL || info->type != IRQT_EVTCHN);
        }

out:
        mutex_unlock(&irq_mapping_update_lock);

        return irq;
}
EXPORT_SYMBOL_GPL(bind_evtchn_to_irq);

static int bind_ipi_to_irq(unsigned int ipi, unsigned int cpu)
{
        struct evtchn_bind_ipi bind_ipi;
        int evtchn, irq;
        int ret;

        mutex_lock(&irq_mapping_update_lock);

        irq = per_cpu(ipi_to_irq, cpu)[ipi];

        if (irq == -1) {
                irq = xen_allocate_irq_dynamic();
                if (irq < 0)
                        goto out;

                irq_set_chip_and_handler_name(irq, &xen_percpu_chip,
                                              handle_percpu_irq, "ipi");

                bind_ipi.vcpu = xen_vcpu_nr(cpu);
                if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_ipi,
                                                &bind_ipi) != 0)
                        BUG();
                evtchn = bind_ipi.port;

                ret = xen_irq_info_ipi_setup(cpu, irq, evtchn, ipi);
                if (ret < 0) {
                        __unbind_from_irq(irq);
                        irq = ret;
                        goto out;
                }
                bind_evtchn_to_cpu(evtchn, cpu);
        } else {
                struct irq_info *info = info_for_irq(irq);
                WARN_ON(info == NULL || info->type != IRQT_IPI);
        }

 out:
        mutex_unlock(&irq_mapping_update_lock);
        return irq;
}

int bind_interdomain_evtchn_to_irq(unsigned int remote_domain,
                                   unsigned int remote_port)
{
        struct evtchn_bind_interdomain bind_interdomain;
        int err;

        bind_interdomain.remote_dom  = remote_domain;
        bind_interdomain.remote_port = remote_port;

        err = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
                                          &bind_interdomain);

        return err ? : bind_evtchn_to_irq(bind_interdomain.local_port);
}
EXPORT_SYMBOL_GPL(bind_interdomain_evtchn_to_irq);

static int find_virq(unsigned int virq, unsigned int cpu)
{
        struct evtchn_status status;
        int port, rc = -ENOENT;

        memset(&status, 0, sizeof(status));
        for (port = 0; port < xen_evtchn_max_channels(); port++) {
                status.dom = DOMID_SELF;
                status.port = port;
                rc = HYPERVISOR_event_channel_op(EVTCHNOP_status, &status);
                if (rc < 0)
                        continue;
                if (status.status != EVTCHNSTAT_virq)
                        continue;
                if (status.u.virq == virq && status.vcpu == xen_vcpu_nr(cpu)) {
                        rc = port;
                        break;
                }
        }
        return rc;
}

/**
 * xen_evtchn_nr_channels - number of usable event channel ports
 *
 * This may be less than the maximum supported by the current
 * hypervisor ABI. Use xen_evtchn_max_channels() for the maximum
 * supported.
 */
unsigned xen_evtchn_nr_channels(void)
{
        return evtchn_ops->nr_channels();
}
EXPORT_SYMBOL_GPL(xen_evtchn_nr_channels);

int bind_virq_to_irq(unsigned int virq, unsigned int cpu, bool percpu)
{
        struct evtchn_bind_virq bind_virq;
        int evtchn, irq, ret;

        mutex_lock(&irq_mapping_update_lock);

        irq = per_cpu(virq_to_irq, cpu)[virq];

        if (irq == -1) {
                irq = xen_allocate_irq_dynamic();
                if (irq < 0)
                        goto out;

                if (percpu)
                        irq_set_chip_and_handler_name(irq, &xen_percpu_chip,
                                                      handle_percpu_irq, "virq");
                else
                        irq_set_chip_and_handler_name(irq, &xen_dynamic_chip,
                                                      handle_edge_irq, "virq");

                bind_virq.virq = virq;
                bind_virq.vcpu = xen_vcpu_nr(cpu);
                ret = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
                                                &bind_virq);
                if (ret == 0)
                        evtchn = bind_virq.port;
                else {
                        if (ret == -EEXIST)
                                ret = find_virq(virq, cpu);
                        BUG_ON(ret < 0);
                        evtchn = ret;
                }

                ret = xen_irq_info_virq_setup(cpu, irq, evtchn, virq);
                if (ret < 0) {
                        __unbind_from_irq(irq);
                        irq = ret;

                        goto out;
                }

                bind_evtchn_to_cpu(evtchn, cpu);
        } else {
                struct irq_info *info = info_for_irq(irq);
                WARN_ON(info == NULL || info->type != IRQT_VIRQ);
        }

out:
        mutex_unlock(&irq_mapping_update_lock);

        return irq;
}

static void unbind_from_irq(unsigned int irq)
{
        mutex_lock(&irq_mapping_update_lock);
        __unbind_from_irq(irq);
        mutex_unlock(&irq_mapping_update_lock);
}

int bind_evtchn_to_irqhandler(unsigned int evtchn,
                              irq_handler_t handler,
                              unsigned long irqflags,
                              const char *devname, void *dev_id)
{
        int irq, retval;

        irq = bind_evtchn_to_irq(evtchn);
        if (irq < 0)
                return irq;
        retval = request_irq(irq, handler, irqflags, devname, dev_id);
        if (retval != 0) {
                unbind_from_irq(irq);
                return retval;
        }

        return irq;
}
EXPORT_SYMBOL_GPL(bind_evtchn_to_irqhandler);

int bind_interdomain_evtchn_to_irqhandler(unsigned int remote_domain,
                                          unsigned int remote_port,
                                          irq_handler_t handler,
                                          unsigned long irqflags,
                                          const char *devname,
                                          void *dev_id)
{
        int irq, retval;

        irq = bind_interdomain_evtchn_to_irq(remote_domain, remote_port);
        if (irq < 0)
                return irq;

        retval = request_irq(irq, handler, irqflags, devname, dev_id);
        if (retval != 0) {
                unbind_from_irq(irq);
                return retval;
        }

        return irq;
}
EXPORT_SYMBOL_GPL(bind_interdomain_evtchn_to_irqhandler);

int bind_virq_to_irqhandler(unsigned int virq, unsigned int cpu,
                            irq_handler_t handler,
                            unsigned long irqflags, const char *devname, void *dev_id)
{
        int irq, retval;

        irq = bind_virq_to_irq(virq, cpu, irqflags & IRQF_PERCPU);
        if (irq < 0)
                return irq;
        retval = request_irq(irq, handler, irqflags, devname, dev_id);
        if (retval != 0) {
                unbind_from_irq(irq);
                return retval;
        }

        return irq;
}
EXPORT_SYMBOL_GPL(bind_virq_to_irqhandler);

int bind_ipi_to_irqhandler(enum ipi_vector ipi,
                           unsigned int cpu,
                           irq_handler_t handler,
                           unsigned long irqflags,
                           const char *devname,
                           void *dev_id)
{
        int irq, retval;

        irq = bind_ipi_to_irq(ipi, cpu);
        if (irq < 0)
                return irq;

        irqflags |= IRQF_NO_SUSPEND | IRQF_FORCE_RESUME | IRQF_EARLY_RESUME;
        retval = request_irq(irq, handler, irqflags, devname, dev_id);
        if (retval != 0) {
                unbind_from_irq(irq);
                return retval;
        }

        return irq;
}

void unbind_from_irqhandler(unsigned int irq, void *dev_id)
{
        struct irq_info *info = irq_get_handler_data(irq);

        if (WARN_ON(!info))
                return;
        free_irq(irq, dev_id);
        unbind_from_irq(irq);
}
EXPORT_SYMBOL_GPL(unbind_from_irqhandler);

/**
 * xen_set_irq_priority() - set an event channel priority.
 * @irq:irq bound to an event channel.
 * @priority: priority between XEN_IRQ_PRIORITY_MAX and XEN_IRQ_PRIORITY_MIN.
 */
int xen_set_irq_priority(unsigned irq, unsigned priority)
{
        struct evtchn_set_priority set_priority;

        set_priority.port = evtchn_from_irq(irq);
        set_priority.priority = priority;

        return HYPERVISOR_event_channel_op(EVTCHNOP_set_priority,
                                           &set_priority);
}
EXPORT_SYMBOL_GPL(xen_set_irq_priority);

int evtchn_make_refcounted(unsigned int evtchn)
{
        int irq = get_evtchn_to_irq(evtchn);
        struct irq_info *info;

        if (irq == -1)
                return -ENOENT;

        info = irq_get_handler_data(irq);

        if (!info)
                return -ENOENT;

        WARN_ON(info->refcnt != -1);

        info->refcnt = 1;

        return 0;
}
EXPORT_SYMBOL_GPL(evtchn_make_refcounted);

int evtchn_get(unsigned int evtchn)
{
        int irq;
        struct irq_info *info;
        int err = -ENOENT;

        if (evtchn >= xen_evtchn_max_channels())
                return -EINVAL;

        mutex_lock(&irq_mapping_update_lock);

        irq = get_evtchn_to_irq(evtchn);
        if (irq == -1)
                goto done;

        info = irq_get_handler_data(irq);

        if (!info)
                goto done;

        err = -EINVAL;
        if (info->refcnt <= 0)
                goto done;

        info->refcnt++;
        err = 0;
 done:
        mutex_unlock(&irq_mapping_update_lock);

        return err;
}
EXPORT_SYMBOL_GPL(evtchn_get);

void evtchn_put(unsigned int evtchn)
{
        int irq = get_evtchn_to_irq(evtchn);
        if (WARN_ON(irq == -1))
                return;
        unbind_from_irq(irq);
}
EXPORT_SYMBOL_GPL(evtchn_put);

void xen_send_IPI_one(unsigned int cpu, enum ipi_vector vector)
{
        int irq;

#ifdef CONFIG_X86
        if (unlikely(vector == XEN_NMI_VECTOR)) {
                int rc =  HYPERVISOR_vcpu_op(VCPUOP_send_nmi, xen_vcpu_nr(cpu),
                                             NULL);
                if (rc < 0)
                        printk(KERN_WARNING "Sending nmi to CPU%d failed (rc:%d)\n", cpu, rc);
                return;
        }
#endif
        irq = per_cpu(ipi_to_irq, cpu)[vector];
        BUG_ON(irq < 0);
        notify_remote_via_irq(irq);
}

static DEFINE_PER_CPU(unsigned, xed_nesting_count);

static void __xen_evtchn_do_upcall(void)
{
        struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
        int cpu = get_cpu();
        unsigned count;

        do {
                vcpu_info->evtchn_upcall_pending = 0;

                if (__this_cpu_inc_return(xed_nesting_count) - 1)
                        goto out;

                xen_evtchn_handle_events(cpu);

                BUG_ON(!irqs_disabled());

                count = __this_cpu_read(xed_nesting_count);
                __this_cpu_write(xed_nesting_count, 0);
        } while (count != 1 || vcpu_info->evtchn_upcall_pending);

out:

        put_cpu();
}

void xen_evtchn_do_upcall(struct pt_regs *regs)
{
        struct pt_regs *old_regs = set_irq_regs(regs);

        irq_enter();
#ifdef CONFIG_X86
        inc_irq_stat(irq_hv_callback_count);
#endif

        __xen_evtchn_do_upcall();

        irq_exit();
        set_irq_regs(old_regs);
}

void xen_hvm_evtchn_do_upcall(void)
{
        __xen_evtchn_do_upcall();
}
EXPORT_SYMBOL_GPL(xen_hvm_evtchn_do_upcall);

/* Rebind a new event channel to an existing irq. */
void rebind_evtchn_irq(int evtchn, int irq)
{
        struct irq_info *info = info_for_irq(irq);

        if (WARN_ON(!info))
                return;

        /* Make sure the irq is masked, since the new event channel
           will also be masked. */
        disable_irq(irq);

        mutex_lock(&irq_mapping_update_lock);

        /* After resume the irq<->evtchn mappings are all cleared out */
        BUG_ON(get_evtchn_to_irq(evtchn) != -1);
        /* Expect irq to have been bound before,
           so there should be a proper type */
        BUG_ON(info->type == IRQT_UNBOUND);

        (void)xen_irq_info_evtchn_setup(irq, evtchn);

        mutex_unlock(&irq_mapping_update_lock);

        bind_evtchn_to_cpu(evtchn, info->cpu);
        /* This will be deferred until interrupt is processed */
        irq_set_affinity(irq, cpumask_of(info->cpu));

        /* Unmask the event channel. */
        enable_irq(irq);
}

/* Rebind an evtchn so that it gets delivered to a specific cpu */
int xen_rebind_evtchn_to_cpu(int evtchn, unsigned tcpu)
{
        struct evtchn_bind_vcpu bind_vcpu;
        int masked;

        if (!VALID_EVTCHN(evtchn))
                return -1;

        if (!xen_support_evtchn_rebind())
                return -1;

        /* Send future instances of this interrupt to other vcpu. */
        bind_vcpu.port = evtchn;
        bind_vcpu.vcpu = xen_vcpu_nr(tcpu);

        /*
         * Mask the event while changing the VCPU binding to prevent
         * it being delivered on an unexpected VCPU.
         */
        masked = test_and_set_mask(evtchn);

        /*
         * If this fails, it usually just indicates that we're dealing with a
         * virq or IPI channel, which don't actually need to be rebound. Ignore
         * it, but don't do the xenlinux-level rebind in that case.
         */
        if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_vcpu, &bind_vcpu) >= 0)
                bind_evtchn_to_cpu(evtchn, tcpu);

        if (!masked)
                unmask_evtchn(evtchn);

        return 0;
}
EXPORT_SYMBOL_GPL(xen_rebind_evtchn_to_cpu);

static int set_affinity_irq(struct irq_data *data, const struct cpumask *dest,
                            bool force)
{
        unsigned tcpu = cpumask_first_and(dest, cpu_online_mask);
        int ret = xen_rebind_evtchn_to_cpu(evtchn_from_irq(data->irq), tcpu);

        if (!ret)
                irq_data_update_effective_affinity(data, cpumask_of(tcpu));

        return ret;
}

static void enable_dynirq(struct irq_data *data)
{
        int evtchn = evtchn_from_irq(data->irq);

        if (VALID_EVTCHN(evtchn))
                unmask_evtchn(evtchn);
}

static void disable_dynirq(struct irq_data *data)
{
        int evtchn = evtchn_from_irq(data->irq);

        if (VALID_EVTCHN(evtchn))
                mask_evtchn(evtchn);
}

static void ack_dynirq(struct irq_data *data)
{
        int evtchn = evtchn_from_irq(data->irq);

        if (!VALID_EVTCHN(evtchn))
                return;

        if (unlikely(irqd_is_setaffinity_pending(data)) &&
            likely(!irqd_irq_disabled(data))) {
                int masked = test_and_set_mask(evtchn);

                clear_evtchn(evtchn);

                irq_move_masked_irq(data);

                if (!masked)
                        unmask_evtchn(evtchn);
        } else
                clear_evtchn(evtchn);
}

static void mask_ack_dynirq(struct irq_data *data)
{
        disable_dynirq(data);
        ack_dynirq(data);
}

static int retrigger_dynirq(struct irq_data *data)
{
        unsigned int evtchn = evtchn_from_irq(data->irq);
        int masked;

        if (!VALID_EVTCHN(evtchn))
                return 0;

        masked = test_and_set_mask(evtchn);
        set_evtchn(evtchn);
        if (!masked)
                unmask_evtchn(evtchn);

        return 1;
}

static void restore_pirqs(void)
{
        int pirq, rc, irq, gsi;
        struct physdev_map_pirq map_irq;
        struct irq_info *info;

        list_for_each_entry(info, &xen_irq_list_head, list) {
                if (info->type != IRQT_PIRQ)
                        continue;

                pirq = info->u.pirq.pirq;
                gsi = info->u.pirq.gsi;
                irq = info->irq;

                /* save/restore of PT devices doesn't work, so at this point the
                 * only devices present are GSI based emulated devices */
                if (!gsi)
                        continue;

                map_irq.domid = DOMID_SELF;
                map_irq.type = MAP_PIRQ_TYPE_GSI;
                map_irq.index = gsi;
                map_irq.pirq = pirq;

                rc = HYPERVISOR_physdev_op(PHYSDEVOP_map_pirq, &map_irq);
                if (rc) {
                        pr_warn("xen map irq failed gsi=%d irq=%d pirq=%d rc=%d\n",
                                gsi, irq, pirq, rc);
                        xen_free_irq(irq);
                        continue;
                }

                printk(KERN_DEBUG "xen: --> irq=%d, pirq=%d\n", irq, map_irq.pirq);

                __startup_pirq(irq);
        }
}

static void restore_cpu_virqs(unsigned int cpu)
{
        struct evtchn_bind_virq bind_virq;
        int virq, irq, evtchn;

        for (virq = 0; virq < NR_VIRQS; virq++) {
                if ((irq = per_cpu(virq_to_irq, cpu)[virq]) == -1)
                        continue;

                BUG_ON(virq_from_irq(irq) != virq);

                /* Get a new binding from Xen. */
                bind_virq.virq = virq;
                bind_virq.vcpu = xen_vcpu_nr(cpu);
                if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
                                                &bind_virq) != 0)
                        BUG();
                evtchn = bind_virq.port;

                /* Record the new mapping. */
                (void)xen_irq_info_virq_setup(cpu, irq, evtchn, virq);
                bind_evtchn_to_cpu(evtchn, cpu);
        }
}

static void restore_cpu_ipis(unsigned int cpu)
{
        struct evtchn_bind_ipi bind_ipi;
        int ipi, irq, evtchn;

        for (ipi = 0; ipi < XEN_NR_IPIS; ipi++) {
                if ((irq = per_cpu(ipi_to_irq, cpu)[ipi]) == -1)
                        continue;

                BUG_ON(ipi_from_irq(irq) != ipi);

                /* Get a new binding from Xen. */
                bind_ipi.vcpu = xen_vcpu_nr(cpu);
                if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_ipi,
                                                &bind_ipi) != 0)
                        BUG();
                evtchn = bind_ipi.port;

                /* Record the new mapping. */
                (void)xen_irq_info_ipi_setup(cpu, irq, evtchn, ipi);
                bind_evtchn_to_cpu(evtchn, cpu);
        }
}

/* Clear an irq's pending state, in preparation for polling on it */
void xen_clear_irq_pending(int irq)
{
        int evtchn = evtchn_from_irq(irq);

        if (VALID_EVTCHN(evtchn))
                clear_evtchn(evtchn);
}
EXPORT_SYMBOL(xen_clear_irq_pending);
void xen_set_irq_pending(int irq)
{
        int evtchn = evtchn_from_irq(irq);

        if (VALID_EVTCHN(evtchn))
                set_evtchn(evtchn);
}

bool xen_test_irq_pending(int irq)
{
        int evtchn = evtchn_from_irq(irq);
        bool ret = false;

        if (VALID_EVTCHN(evtchn))
                ret = test_evtchn(evtchn);

        return ret;
}

/* Poll waiting for an irq to become pending with timeout.  In the usual case,
 * the irq will be disabled so it won't deliver an interrupt. */
void xen_poll_irq_timeout(int irq, u64 timeout)
{
        evtchn_port_t evtchn = evtchn_from_irq(irq);

        if (VALID_EVTCHN(evtchn)) {
                struct sched_poll poll;

                poll.nr_ports = 1;
                poll.timeout = timeout;
                set_xen_guest_handle(poll.ports, &evtchn);

                if (HYPERVISOR_sched_op(SCHEDOP_poll, &poll) != 0)
                        BUG();
        }
}
EXPORT_SYMBOL(xen_poll_irq_timeout);
/* Poll waiting for an irq to become pending.  In the usual case, the
 * irq will be disabled so it won't deliver an interrupt. */
void xen_poll_irq(int irq)
{
        xen_poll_irq_timeout(irq, 0 /* no timeout */);
}

/* Check whether the IRQ line is shared with other guests. */
int xen_test_irq_shared(int irq)
{
        struct irq_info *info = info_for_irq(irq);
        struct physdev_irq_status_query irq_status;

        if (WARN_ON(!info))
                return -ENOENT;

        irq_status.irq = info->u.pirq.pirq;

        if (HYPERVISOR_physdev_op(PHYSDEVOP_irq_status_query, &irq_status))
                return 0;
        return !(irq_status.flags & XENIRQSTAT_shared);
}
EXPORT_SYMBOL_GPL(xen_test_irq_shared);

void xen_irq_resume(void)
{
        unsigned int cpu;
        struct irq_info *info;

        /* New event-channel space is not 'live' yet. */
        xen_evtchn_resume();

        /* No IRQ <-> event-channel mappings. */
        list_for_each_entry(info, &xen_irq_list_head, list)
                info->evtchn = 0; /* zap event-channel binding */

        clear_evtchn_to_irq_all();

        for_each_possible_cpu(cpu) {
                restore_cpu_virqs(cpu);
                restore_cpu_ipis(cpu);
        }

        restore_pirqs();
}

static struct irq_chip xen_dynamic_chip __read_mostly = {
        .name                   = "xen-dyn",

        .irq_disable            = disable_dynirq,
        .irq_mask               = disable_dynirq,
        .irq_unmask             = enable_dynirq,

        .irq_ack                = ack_dynirq,
        .irq_mask_ack           = mask_ack_dynirq,

        .irq_set_affinity       = set_affinity_irq,
        .irq_retrigger          = retrigger_dynirq,
};

static struct irq_chip xen_pirq_chip __read_mostly = {
        .name                   = "xen-pirq",

        .irq_startup            = startup_pirq,
        .irq_shutdown           = shutdown_pirq,
        .irq_enable             = enable_pirq,
        .irq_disable            = disable_pirq,

        .irq_mask               = disable_dynirq,
        .irq_unmask             = enable_dynirq,

        .irq_ack                = eoi_pirq,
        .irq_eoi                = eoi_pirq,
        .irq_mask_ack           = mask_ack_pirq,

        .irq_set_affinity       = set_affinity_irq,

        .irq_retrigger          = retrigger_dynirq,
};

static struct irq_chip xen_percpu_chip __read_mostly = {
        .name                   = "xen-percpu",

        .irq_disable            = disable_dynirq,
        .irq_mask               = disable_dynirq,
        .irq_unmask             = enable_dynirq,

        .irq_ack                = ack_dynirq,
};

int xen_set_callback_via(uint64_t via)
{
        struct xen_hvm_param a;
        a.domid = DOMID_SELF;
        a.index = HVM_PARAM_CALLBACK_IRQ;
        a.value = via;
        return HYPERVISOR_hvm_op(HVMOP_set_param, &a);
}
EXPORT_SYMBOL_GPL(xen_set_callback_via);

#ifdef CONFIG_XEN_PVHVM
/* Vector callbacks are better than PCI interrupts to receive event
 * channel notifications because we can receive vector callbacks on any
 * vcpu and we don't need PCI support or APIC interactions. */
void xen_callback_vector(void)
{
        int rc;
        uint64_t callback_via;

        if (xen_have_vector_callback) {
                callback_via = HVM_CALLBACK_VECTOR(HYPERVISOR_CALLBACK_VECTOR);
                rc = xen_set_callback_via(callback_via);
                if (rc) {
                        pr_err("Request for Xen HVM callback vector failed\n");
                        xen_have_vector_callback = 0;
                        return;
                }
                pr_info("Xen HVM callback vector for event delivery is enabled\n");
                alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR,
                                xen_hvm_callback_vector);
        }
}
#else
void xen_callback_vector(void) {}
#endif

#undef MODULE_PARAM_PREFIX
#define MODULE_PARAM_PREFIX "xen."

static bool fifo_events = true;
module_param(fifo_events, bool, 0);

void __init xen_init_IRQ(void)
{
        int ret = -EINVAL;
        unsigned int evtchn;

        if (fifo_events)
                ret = xen_evtchn_fifo_init();
        if (ret < 0)
                xen_evtchn_2l_init();

        evtchn_to_irq = kcalloc(EVTCHN_ROW(xen_evtchn_max_channels()),
                                sizeof(*evtchn_to_irq), GFP_KERNEL);
        BUG_ON(!evtchn_to_irq);

        /* No event channels are 'live' right now. */
        for (evtchn = 0; evtchn < xen_evtchn_nr_channels(); evtchn++)
                mask_evtchn(evtchn);

        pirq_needs_eoi = pirq_needs_eoi_flag;

#ifdef CONFIG_X86
        if (xen_pv_domain()) {
                irq_ctx_init(smp_processor_id());
                if (xen_initial_domain())
                        pci_xen_initial_domain();
        }
        if (xen_feature(XENFEAT_hvm_callback_vector))
                xen_callback_vector();

        if (xen_hvm_domain()) {
                native_init_IRQ();
                /* pci_xen_hvm_init must be called after native_init_IRQ so that
                 * __acpi_register_gsi can point at the right function */
                pci_xen_hvm_init();
        } else {
                int rc;
                struct physdev_pirq_eoi_gmfn eoi_gmfn;

                pirq_eoi_map = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
                eoi_gmfn.gmfn = virt_to_gfn(pirq_eoi_map);
                rc = HYPERVISOR_physdev_op(PHYSDEVOP_pirq_eoi_gmfn_v2, &eoi_gmfn);
                if (rc != 0) {
                        free_page((unsigned long) pirq_eoi_map);
                        pirq_eoi_map = NULL;
                } else
                        pirq_needs_eoi = pirq_check_eoi_map;
        }
#endif
}