events.c

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/*
 * 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 <[email protected]>, XenSource Inc, 2007
 */

#include <linux/linkage.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/module.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/idle.h>
#include <asm/io_apic.h>
#include <asm/xen/page.h>
#include <asm/xen/pci.h>
#endif
#include <asm/sync_bitops.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.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 <asm/hw_irq.h>

/*
 * 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};

/* Interrupt types. */
enum xen_irq_type {
    IRQT_UNBOUND = 0,
    IRQT_PIRQ,
    IRQT_VIRQ,
    IRQT_IPI,
    IRQT_EVTCHN
};

/*
 * Packed IRQ information:
 * type - enum xen_irq_type
 * event channel - irq->event channel mapping
 * cpu - cpu this event channel is bound to
 * index - type-specific information:
 *    PIRQ - vector, with MSB being "needs EIO", or physical IRQ of the HVM
 *           guest, or GSI (real passthrough IRQ) of the device.
 *    VIRQ - virq number
 *    IPI - IPI vector
 *    EVTCHN -
 */
struct irq_info {
    struct list_head list;
    int refcnt;
    enum xen_irq_type type; /* type */
    unsigned irq;
    unsigned short evtchn;  /* event channel */
    unsigned short cpu; /* cpu bound */

    union {
        unsigned short virq;
        enum ipi_vector ipi;
        struct {
            unsigned short pirq;
            unsigned short gsi;
            unsigned char vector;
            unsigned char flags;
            uint16_t domid;
        } pirq;
    } u;
};
#define PIRQ_NEEDS_EOI  (1 << 0)
#define PIRQ_SHAREABLE  (1 << 1)

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

static DEFINE_PER_CPU(unsigned long [NR_EVENT_CHANNELS/BITS_PER_LONG],
              cpu_evtchn_mask);

/* 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);

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

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

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

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

    evtchn_to_irq[evtchn] = irq;
}

static void xen_irq_info_evtchn_init(unsigned irq,
                     unsigned short evtchn)
{
    struct irq_info *info = info_for_irq(irq);

    xen_irq_info_common_init(info, irq, IRQT_EVTCHN, evtchn, 0);
}

static void xen_irq_info_ipi_init(unsigned cpu,
                  unsigned irq,
                  unsigned short evtchn,
                  enum ipi_vector ipi)
{
    struct irq_info *info = info_for_irq(irq);

    xen_irq_info_common_init(info, irq, IRQT_IPI, evtchn, 0);

    info->u.ipi = ipi;

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

static void xen_irq_info_virq_init(unsigned cpu,
                   unsigned irq,
                   unsigned short evtchn,
                   unsigned short virq)
{
    struct irq_info *info = info_for_irq(irq);

    xen_irq_info_common_init(info, irq, IRQT_VIRQ, evtchn, 0);

    info->u.virq = virq;

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

static void xen_irq_info_pirq_init(unsigned irq,
                   unsigned short evtchn,
                   unsigned short pirq,
                   unsigned short gsi,
                   unsigned short vector,
                   uint16_t domid,
                   unsigned char flags)
{
    struct irq_info *info = info_for_irq(irq);

    xen_irq_info_common_init(info, irq, IRQT_PIRQ, evtchn, 0);

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

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

    return info_for_irq(irq)->evtchn;
}

unsigned irq_from_evtchn(unsigned int evtchn)
{
    return evtchn_to_irq[evtchn];
}
EXPORT_SYMBOL_GPL(irq_from_evtchn);

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;
}

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

static unsigned int cpu_from_evtchn(unsigned int evtchn)
{
    int irq = 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 inline unsigned long active_evtchns(unsigned int cpu,
                       struct shared_info *sh,
                       unsigned int idx)
{
    return sh->evtchn_pending[idx] &
        per_cpu(cpu_evtchn_mask, cpu)[idx] &
        ~sh->evtchn_mask[idx];
}

static void bind_evtchn_to_cpu(unsigned int chn, unsigned int cpu)
{
    int irq = evtchn_to_irq[chn];

    BUG_ON(irq == -1);
#ifdef CONFIG_SMP
    cpumask_copy(irq_to_desc(irq)->irq_data.affinity, cpumask_of(cpu));
#endif

    clear_bit(chn, per_cpu(cpu_evtchn_mask, cpu_from_irq(irq)));
    set_bit(chn, per_cpu(cpu_evtchn_mask, cpu));

    info_for_irq(irq)->cpu = cpu;
}

static void init_evtchn_cpu_bindings(void)
{
    int i;
#ifdef CONFIG_SMP
    struct irq_info *info;

    /* By default all event channels notify CPU#0. */
    list_for_each_entry(info, &xen_irq_list_head, list) {
        struct irq_desc *desc = irq_to_desc(info->irq);
        cpumask_copy(desc->irq_data.affinity, cpumask_of(0));
    }
#endif

    for_each_possible_cpu(i)
        memset(per_cpu(cpu_evtchn_mask, i),
               (i == 0) ? ~0 : 0, sizeof(*per_cpu(cpu_evtchn_mask, i)));
}

static inline void clear_evtchn(int port)
{
    struct shared_info *s = HYPERVISOR_shared_info;
    sync_clear_bit(port, &s->evtchn_pending[0]);
}

static inline void set_evtchn(int port)
{
    struct shared_info *s = HYPERVISOR_shared_info;
    sync_set_bit(port, &s->evtchn_pending[0]);
}

static inline int test_evtchn(int port)
{
    struct shared_info *s = HYPERVISOR_shared_info;
    return sync_test_bit(port, &s->evtchn_pending[0]);
}


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 mask_evtchn(int port)
{
    struct shared_info *s = HYPERVISOR_shared_info;
    sync_set_bit(port, &s->evtchn_mask[0]);
}

static void unmask_evtchn(int port)
{
    struct shared_info *s = HYPERVISOR_shared_info;
    unsigned int cpu = get_cpu();
    int do_hypercall = 0, evtchn_pending = 0;

    BUG_ON(!irqs_disabled());

    if (unlikely((cpu != cpu_from_evtchn(port))))
        do_hypercall = 1;
    else
        evtchn_pending = sync_test_bit(port, &s->evtchn_pending[0]);

    if (unlikely(evtchn_pending && xen_hvm_domain()))
        do_hypercall = 1;

    /* Slow path (hypercall) if this is a non-local port or if this is
     * an hvm domain and an event is pending (hvm domains don't have
     * their own implementation of irq_enable). */
    if (do_hypercall) {
        struct evtchn_unmask unmask = { .port = port };
        (void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask);
    } else {
        struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);

        sync_clear_bit(port, &s->evtchn_mask[0]);

        /*
         * The following is basically the equivalent of
         * 'hw_resend_irq'. Just like a real IO-APIC we 'lose
         * the interrupt edge' if the channel is masked.
         */
        if (evtchn_pending &&
            !sync_test_and_set_bit(port / BITS_PER_LONG,
                       &vcpu_info->evtchn_pending_sel))
            vcpu_info->evtchn_upcall_pending = 1;
    }

    put_cpu();
}

static void xen_irq_init(unsigned irq)
{
    struct irq_info *info;
#ifdef CONFIG_SMP
    struct irq_desc *desc = irq_to_desc(irq);

    /* By default all event channels notify CPU#0. */
    cpumask_copy(desc->irq_data.affinity, 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_irq_dynamic(void)
{
    int first = 0;
    int irq;

#ifdef CONFIG_X86_IO_APIC
    /*
     * For an HVM guest or domain 0 which see "real" (emulated or
     * actual respectively) GSIs we allocate dynamic IRQs
     * e.g. those corresponding to event channels or MSIs
     * etc. from the range above those "real" GSIs to avoid
     * collisions.
     */
    if (xen_initial_domain() || xen_hvm_domain())
        first = get_nr_irqs_gsi();
#endif

    irq = irq_alloc_desc_from(first, -1);

    if (irq >= 0)
        xen_irq_init(irq);

    return irq;
}

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_IRQS_LEGACY)
        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);

    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_IRQS_LEGACY)
        return;

    irq_free_desc(irq);
}

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 bool probing_irq(int irq)
{
    struct irq_desc *desc = irq_to_desc(irq);

    return desc && desc->action == NULL;
}

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;

    irq_move_irq(data);

    if (VALID_EVTCHN(evtchn))
        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) {
        if (!probing_irq(irq))
            printk(KERN_INFO "Failed to obtain physical IRQ %d\n",
                   irq);
        return 0;
    }
    evtchn = bind_pirq.port;

    pirq_query_unmask(irq);

    evtchn_to_irq[evtchn] = irq;
    bind_evtchn_to_cpu(evtchn, 0);
    info->evtchn = evtchn;

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

    return 0;
}

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

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

    BUG_ON(info->type != IRQT_PIRQ);

    if (!VALID_EVTCHN(evtchn))
        return;

    mask_evtchn(evtchn);

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

    bind_evtchn_to_cpu(evtchn, 0);
    evtchn_to_irq[evtchn] = -1;
    info->evtchn = 0;
}

static void enable_pirq(struct irq_data *data)
{
    startup_pirq(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);

/*
 * 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;

    mutex_lock(&irq_mapping_update_lock);

    irq = xen_irq_from_gsi(gsi);
    if (irq != -1) {
        printk(KERN_INFO "xen_map_pirq_gsi: returning irq %d for gsi %u\n",
               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;
    }

    xen_irq_info_pirq_init(irq, 0, pirq, gsi, irq_op.vector, DOMID_SELF,
                   shareable ? PIRQ_SHAREABLE : 0);

    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 vector, const char *name,
                 domid_t domid)
{
    int irq, ret;

    mutex_lock(&irq_mapping_update_lock);

    irq = xen_allocate_irq_dynamic();
    if (irq < 0)
        goto out;

    irq_set_chip_and_handler_name(irq, &xen_pirq_chip, handle_edge_irq,
            name);

    xen_irq_info_pirq_init(irq, 0, pirq, 0, vector, domid, 0);
    ret = irq_set_msi_desc(irq, msidesc);
    if (ret < 0)
        goto error_irq;
out:
    mutex_unlock(&irq_mapping_update_lock);
    return irq;
error_irq:
    mutex_unlock(&irq_mapping_update_lock);
    xen_free_irq(irq);
    return ret;
}
#endif

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

    mutex_lock(&irq_mapping_update_lock);

    desc = irq_to_desc(irq);
    if (!desc)
        goto out;

    if (xen_initial_domain()) {
        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))
            printk(KERN_INFO "domain %d does not have %d anymore\n",
                info->u.pirq.domid, info->u.pirq.pirq);
        else if (rc) {
            printk(KERN_WARNING "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;

    mutex_lock(&irq_mapping_update_lock);

    irq = evtchn_to_irq[evtchn];

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

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

        xen_irq_info_evtchn_init(irq, evtchn);
    } else {
        struct irq_info *info = info_for_irq(irq);
        WARN_ON(info == NULL || info->type != IRQT_EVTCHN);
    }
    irq_clear_status_flags(irq, IRQ_NOREQUEST|IRQ_NOAUTOEN);

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;

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

        xen_irq_info_ipi_init(cpu, irq, evtchn, ipi);

        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;
}

static 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);
}

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 <= NR_EVENT_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 == cpu) {
            rc = port;
            break;
        }
    }
    return rc;
}

int bind_virq_to_irq(unsigned int virq, unsigned int cpu)
{
    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 == -1)
            goto out;

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

        bind_virq.virq = virq;
        bind_virq.vcpu = 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;
        }

        xen_irq_info_virq_init(cpu, irq, evtchn, virq);

        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)
{
    struct evtchn_close close;
    int evtchn = evtchn_from_irq(irq);
    struct irq_info *info = irq_get_handler_data(irq);

    mutex_lock(&irq_mapping_update_lock);

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

    if (VALID_EVTCHN(evtchn)) {
        close.port = evtchn;
        if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
            BUG();

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

        /* Closed ports are implicitly re-bound to VCPU0. */
        bind_evtchn_to_cpu(evtchn, 0);

        evtchn_to_irq[evtchn] = -1;
    }

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

    xen_free_irq(irq);

 done:
    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);
    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)
{
    free_irq(irq, dev_id);
    unbind_from_irq(irq);
}
EXPORT_SYMBOL_GPL(unbind_from_irqhandler);

int evtchn_make_refcounted(unsigned int evtchn)
{
    int irq = 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 >= NR_EVENT_CHANNELS)
        return -EINVAL;

    mutex_lock(&irq_mapping_update_lock);

    irq = 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 = 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 = per_cpu(ipi_to_irq, cpu)[vector];
    BUG_ON(irq < 0);
    notify_remote_via_irq(irq);
}

irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
{
    struct shared_info *sh = HYPERVISOR_shared_info;
    int cpu = smp_processor_id();
    unsigned long *cpu_evtchn = per_cpu(cpu_evtchn_mask, cpu);
    int i;
    unsigned long flags;
    static DEFINE_SPINLOCK(debug_lock);
    struct vcpu_info *v;

    spin_lock_irqsave(&debug_lock, flags);

    printk("\nvcpu %d\n  ", cpu);

    for_each_online_cpu(i) {
        int pending;
        v = per_cpu(xen_vcpu, i);
        pending = (get_irq_regs() && i == cpu)
            ? xen_irqs_disabled(get_irq_regs())
            : v->evtchn_upcall_mask;
        printk("%d: masked=%d pending=%d event_sel %0*lx\n  ", i,
               pending, v->evtchn_upcall_pending,
               (int)(sizeof(v->evtchn_pending_sel)*2),
               v->evtchn_pending_sel);
    }
    v = per_cpu(xen_vcpu, cpu);

    printk("\npending:\n   ");
    for (i = ARRAY_SIZE(sh->evtchn_pending)-1; i >= 0; i--)
        printk("%0*lx%s", (int)sizeof(sh->evtchn_pending[0])*2,
               sh->evtchn_pending[i],
               i % 8 == 0 ? "\n   " : " ");
    printk("\nglobal mask:\n   ");
    for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)
        printk("%0*lx%s",
               (int)(sizeof(sh->evtchn_mask[0])*2),
               sh->evtchn_mask[i],
               i % 8 == 0 ? "\n   " : " ");

    printk("\nglobally unmasked:\n   ");
    for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)
        printk("%0*lx%s", (int)(sizeof(sh->evtchn_mask[0])*2),
               sh->evtchn_pending[i] & ~sh->evtchn_mask[i],
               i % 8 == 0 ? "\n   " : " ");

    printk("\nlocal cpu%d mask:\n   ", cpu);
    for (i = (NR_EVENT_CHANNELS/BITS_PER_LONG)-1; i >= 0; i--)
        printk("%0*lx%s", (int)(sizeof(cpu_evtchn[0])*2),
               cpu_evtchn[i],
               i % 8 == 0 ? "\n   " : " ");

    printk("\nlocally unmasked:\n   ");
    for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--) {
        unsigned long pending = sh->evtchn_pending[i]
            & ~sh->evtchn_mask[i]
            & cpu_evtchn[i];
        printk("%0*lx%s", (int)(sizeof(sh->evtchn_mask[0])*2),
               pending, i % 8 == 0 ? "\n   " : " ");
    }

    printk("\npending list:\n");
    for (i = 0; i < NR_EVENT_CHANNELS; i++) {
        if (sync_test_bit(i, sh->evtchn_pending)) {
            int word_idx = i / BITS_PER_LONG;
            printk("  %d: event %d -> irq %d%s%s%s\n",
                   cpu_from_evtchn(i), i,
                   evtchn_to_irq[i],
                   sync_test_bit(word_idx, &v->evtchn_pending_sel)
                         ? "" : " l2-clear",
                   !sync_test_bit(i, sh->evtchn_mask)
                         ? "" : " globally-masked",
                   sync_test_bit(i, cpu_evtchn)
                         ? "" : " locally-masked");
        }
    }

    spin_unlock_irqrestore(&debug_lock, flags);

    return IRQ_HANDLED;
}

static DEFINE_PER_CPU(unsigned, xed_nesting_count);
static DEFINE_PER_CPU(unsigned int, current_word_idx);
static DEFINE_PER_CPU(unsigned int, current_bit_idx);

/*
 * Mask out the i least significant bits of w
 */
#define MASK_LSBS(w, i) (w & ((~0UL) << i))

/*
 * Search the CPUs pending events bitmasks.  For each one found, map
 * the event number to an irq, and feed it into do_IRQ() for
 * handling.
 *
 * Xen uses a two-level bitmap to speed searching.  The first level is
 * a bitset of words which contain pending event bits.  The second
 * level is a bitset of pending events themselves.
 */
static void __xen_evtchn_do_upcall(void)
{
    int start_word_idx, start_bit_idx;
    int word_idx, bit_idx;
    int i;
    int cpu = get_cpu();
    struct shared_info *s = HYPERVISOR_shared_info;
    struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
    unsigned count;

    do {
        unsigned long pending_words;

        vcpu_info->evtchn_upcall_pending = 0;

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

#ifndef CONFIG_X86 /* No need for a barrier -- XCHG is a barrier on x86. */
        /* Clear master flag /before/ clearing selector flag. */
        wmb();
#endif
        pending_words = xchg(&vcpu_info->evtchn_pending_sel, 0);

        start_word_idx = __this_cpu_read(current_word_idx);
        start_bit_idx = __this_cpu_read(current_bit_idx);

        word_idx = start_word_idx;

        for (i = 0; pending_words != 0; i++) {
            unsigned long pending_bits;
            unsigned long words;

            words = MASK_LSBS(pending_words, word_idx);

            /*
             * If we masked out all events, wrap to beginning.
             */
            if (words == 0) {
                word_idx = 0;
                bit_idx = 0;
                continue;
            }
            word_idx = __ffs(words);

            pending_bits = active_evtchns(cpu, s, word_idx);
            bit_idx = 0; /* usually scan entire word from start */
            if (word_idx == start_word_idx) {
                /* We scan the starting word in two parts */
                if (i == 0)
                    /* 1st time: start in the middle */
                    bit_idx = start_bit_idx;
                else
                    /* 2nd time: mask bits done already */
                    bit_idx &= (1UL << start_bit_idx) - 1;
            }

            do {
                unsigned long bits;
                int port, irq;
                struct irq_desc *desc;

                bits = MASK_LSBS(pending_bits, bit_idx);

                /* If we masked out all events, move on. */
                if (bits == 0)
                    break;

                bit_idx = __ffs(bits);

                /* Process port. */
                port = (word_idx * BITS_PER_LONG) + bit_idx;
                irq = evtchn_to_irq[port];

                if (irq != -1) {
                    desc = irq_to_desc(irq);
                    if (desc)
                        generic_handle_irq_desc(irq, desc);
                }

                bit_idx = (bit_idx + 1) % BITS_PER_LONG;

                /* Next caller starts at last processed + 1 */
                __this_cpu_write(current_word_idx,
                         bit_idx ? word_idx :
                         (word_idx+1) % BITS_PER_LONG);
                __this_cpu_write(current_bit_idx, bit_idx);
            } while (bit_idx != 0);

            /* Scan start_l1i twice; all others once. */
            if ((word_idx != start_word_idx) || (i != 0))
                pending_words &= ~(1UL << word_idx);

            word_idx = (word_idx + 1) % BITS_PER_LONG;
        }

        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
    exit_idle();
#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);

    /* 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(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);

    xen_irq_info_evtchn_init(irq, evtchn);

    mutex_unlock(&irq_mapping_update_lock);

    /* new event channels are always bound to cpu 0 */
    irq_set_affinity(irq, cpumask_of(0));

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

/* Rebind an evtchn so that it gets delivered to a specific cpu */
static int rebind_irq_to_cpu(unsigned irq, unsigned tcpu)
{
    struct evtchn_bind_vcpu bind_vcpu;
    int evtchn = evtchn_from_irq(irq);

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

    /*
     * Events delivered via platform PCI interrupts are always
     * routed to vcpu 0 and hence cannot be rebound.
     */
    if (xen_hvm_domain() && !xen_have_vector_callback)
        return -1;

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

    /*
     * 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);

    return 0;
}

static int set_affinity_irq(struct irq_data *data, const struct cpumask *dest,
                bool force)
{
    unsigned tcpu = cpumask_first(dest);

    return rebind_irq_to_cpu(data->irq, tcpu);
}

int resend_irq_on_evtchn(unsigned int irq)
{
    int masked, evtchn = evtchn_from_irq(irq);
    struct shared_info *s = HYPERVISOR_shared_info;

    if (!VALID_EVTCHN(evtchn))
        return 1;

    masked = sync_test_and_set_bit(evtchn, s->evtchn_mask);
    sync_set_bit(evtchn, s->evtchn_pending);
    if (!masked)
        unmask_evtchn(evtchn);

    return 1;
}

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);

    irq_move_irq(data);

    if (VALID_EVTCHN(evtchn))
        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)
{
    int evtchn = evtchn_from_irq(data->irq);
    struct shared_info *sh = HYPERVISOR_shared_info;
    int ret = 0;

    if (VALID_EVTCHN(evtchn)) {
        int masked;

        masked = sync_test_and_set_bit(evtchn, sh->evtchn_mask);
        sync_set_bit(evtchn, sh->evtchn_pending);
        if (!masked)
            unmask_evtchn(evtchn);
        ret = 1;
    }

    return ret;
}

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) {
            printk(KERN_WARNING "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 = cpu;
        if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
                        &bind_virq) != 0)
            BUG();
        evtchn = bind_virq.port;

        /* Record the new mapping. */
        xen_irq_info_virq_init(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 = cpu;
        if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_ipi,
                        &bind_ipi) != 0)
            BUG();
        evtchn = bind_ipi.port;

        /* Record the new mapping. */
        xen_irq_info_ipi_init(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 = { .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, evtchn;
    struct irq_info *info;

    init_evtchn_cpu_bindings();

    /* New event-channel space is not 'live' yet. */
    for (evtchn = 0; evtchn < NR_EVENT_CHANNELS; evtchn++)
        mask_evtchn(evtchn);

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

    for (evtchn = 0; evtchn < NR_EVENT_CHANNELS; evtchn++)
        evtchn_to_irq[evtchn] = -1;

    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(XEN_HVM_EVTCHN_CALLBACK);
        rc = xen_set_callback_via(callback_via);
        if (rc) {
            printk(KERN_ERR "Request for Xen HVM callback vector"
                    " failed.\n");
            xen_have_vector_callback = 0;
            return;
        }
        printk(KERN_INFO "Xen HVM callback vector for event delivery is "
                "enabled\n");
        /* in the restore case the vector has already been allocated */
        if (!test_bit(XEN_HVM_EVTCHN_CALLBACK, used_vectors))
            alloc_intr_gate(XEN_HVM_EVTCHN_CALLBACK, xen_hvm_callback_vector);
    }
}
#else
void xen_callback_vector(void) {}
#endif

void __init xen_init_IRQ(void)
{
    int i;

    evtchn_to_irq = kcalloc(NR_EVENT_CHANNELS, sizeof(*evtchn_to_irq),
                    GFP_KERNEL);
    BUG_ON(!evtchn_to_irq);
    for (i = 0; i < NR_EVENT_CHANNELS; i++)
        evtchn_to_irq[i] = -1;

    init_evtchn_cpu_bindings();

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

    pirq_needs_eoi = pirq_needs_eoi_flag;

#ifdef CONFIG_X86
    if (xen_hvm_domain()) {
        xen_callback_vector();
        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;

        irq_ctx_init(smp_processor_id());
        if (xen_initial_domain())
            pci_xen_initial_domain();

        pirq_eoi_map = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
        eoi_gmfn.gmfn = virt_to_mfn(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
}