text: /*
   * 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/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/i8259.h>
  #include <asm/xen/pci.h>
  #include <xen/page.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 <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_irq_data(irq)->affinity, cpumask_of(cpu));
  #endif
  	xen_evtchn_port_bind_to_cpu(info, cpu);
  
  	info->cpu = cpu;
  }
  
  static void xen_evtchn_mask_all(void)
  {
  	unsigned int evtchn;
  
  	for (evtchn = 0; evtchn < xen_evtchn_nr_channels(); evtchn++)
  		mask_evtchn(evtchn);
  }
  
  /**
   * 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_irq_data(irq)->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_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;
  
  	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) {
  		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)
  {
  	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);
  
  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 = 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 == 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 = 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, 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
  	exit_idle();
  	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 */
  static int rebind_irq_to_cpu(unsigned irq, unsigned tcpu)
  {
  	struct evtchn_bind_vcpu bind_vcpu;
  	int evtchn = evtchn_from_irq(irq);
  	int masked;
  
  	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;
  
  	/*
  	 * 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;
  }
  
  static int set_affinity_irq(struct irq_data *data, const struct cpumask *dest,
  			    bool force)
  {
  	unsigned tcpu = cpumask_first_and(dest, cpu_online_mask);
  
  	return rebind_irq_to_cpu(data->irq, tcpu);
  }
  
  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)
  {
  	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 = 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 = 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_mask_all();
  	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");
  		/* in the restore case the vector has already been allocated */
  		if (!test_bit(HYPERVISOR_CALLBACK_VECTOR, used_vectors))
  			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;
  
  	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. */
  	xen_evtchn_mask_all();
  
  	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_mfn(pirq_eoi_map);
  		rc = HYPERVISOR_physdev_op(PHYSDEVOP_pirq_eoi_gmfn_v2, &eoi_gmfn);
  		/* TODO: No PVH support for PIRQ EOI */
  		if (rc != 0) {
  			free_page((unsigned long) pirq_eoi_map);
  			pirq_eoi_map = NULL;
  		} else
  			pirq_needs_eoi = pirq_check_eoi_map;
  	}
  #endif
  }
  