void unbind_all_ports(void)
{
    int i;
    int cpu = 0;
    shared_info_t *s = HYPERVISOR_shared_info;
    vcpu_info_t   *vcpu_info = &s->vcpu_info[cpu];
    int rc;

    for ( i = 0; i < NR_EVS; i++ )
    {
        if ( i == start_info.console.domU.evtchn ||
             i == start_info.store_evtchn)
            continue;

        if ( test_and_clear_bit(i, bound_ports) )
        {
            struct evtchn_close close;
            printk("port %d still bound!\n", i);
            mask_evtchn(i);
            close.port = i;
            rc = HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);
            if ( rc )
                printk("WARN: close_port %s failed rc=%d. ignored\n", i, rc);
            clear_evtchn(i);
        }
    }
    vcpu_info->evtchn_upcall_pending = 0;
    vcpu_info->evtchn_pending_sel = 0;
}

/* Set up event channel for xenstored which is run as a local process
 * (this is normally used only in dom0)
 */
static int __init xenstored_local_init(void)
{
	int err = 0;
	unsigned long page = 0;
	struct evtchn_alloc_unbound alloc_unbound;

	/* Allocate Xenstore page */
	page = get_zeroed_page(GFP_KERNEL);
	if (!page)
		goto out_err;

	xen_store_gfn = xen_start_info->store_mfn = virt_to_gfn((void *)page);

	/* Next allocate a local port which xenstored can bind to */
	alloc_unbound.dom        = DOMID_SELF;
	alloc_unbound.remote_dom = DOMID_SELF;

	err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
					  &alloc_unbound);
	if (err == -ENOSYS)
		goto out_err;

	BUG_ON(err);
	xen_store_evtchn = xen_start_info->store_evtchn =
		alloc_unbound.port;

	return 0;

 out_err:
	if (page != 0)
		free_page(page);
	return err;
}

static int 
bind_virq_to_irq(unsigned int virq, unsigned int cpu)
{
	struct evtchn_bind_virq bind_virq;
	int evtchn = 0, irq;

	mtx_lock_spin(&irq_mapping_update_lock);

	if ((irq = pcpu_find(cpu)->pc_virq_to_irq[virq]) == -1) {
		if ((irq = find_unbound_irq()) < 0)
			goto out;

		bind_virq.virq = virq;
		bind_virq.vcpu = cpu;
		HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq, &bind_virq);

		evtchn = bind_virq.port;

		evtchn_to_irq[evtchn] = irq;
		irq_info[irq] = mk_irq_info(IRQT_VIRQ, virq, evtchn);

		pcpu_find(cpu)->pc_virq_to_irq[virq] = irq;

		bind_evtchn_to_cpu(evtchn, cpu);
	}

	irq_bindcount[irq]++;
	unmask_evtchn(evtchn);
out:
	mtx_unlock_spin(&irq_mapping_update_lock);

	return irq;
}

static int
bind_local_port_to_irq(unsigned int local_port)
{
        int irq;

        mtx_lock_spin(&irq_mapping_update_lock);

        KASSERT(evtchn_to_irq[local_port] == -1,
	    ("evtchn_to_irq inconsistent"));
	
        if ((irq = find_unbound_irq()) < 0) {
                struct evtchn_close close = { .port = local_port };
                HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);
		
                goto out;
        }

        evtchn_to_irq[local_port] = irq;
        irq_info[irq] = mk_irq_info(IRQT_LOCAL_PORT, 0, local_port);
        irq_bindcount[irq]++;
	unmask_evtchn(local_port);

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

int 
bind_ipi_to_irq(unsigned int ipi, unsigned int cpu)
{
	struct evtchn_bind_ipi bind_ipi;
	int irq;
	int evtchn = 0;

	mtx_lock_spin(&irq_mapping_update_lock);
	
	if ((irq = pcpu_find(cpu)->pc_ipi_to_irq[ipi]) == -1) {
		if ((irq = find_unbound_irq()) < 0)
			goto out;

		bind_ipi.vcpu = cpu;
		HYPERVISOR_event_channel_op(EVTCHNOP_bind_ipi, &bind_ipi);
		evtchn = bind_ipi.port;

		evtchn_to_irq[evtchn] = irq;
		irq_info[irq] = mk_irq_info(IRQT_IPI, ipi, evtchn);

		pcpu_find(cpu)->pc_ipi_to_irq[ipi] = irq;

		bind_evtchn_to_cpu(evtchn, cpu);
	}
	irq_bindcount[irq]++;
	unmask_evtchn(evtchn);
out:
	
	mtx_unlock_spin(&irq_mapping_update_lock);

	return irq;
}

static void 
unbind_from_irq(int irq)
{
	struct evtchn_close close;
	int evtchn = evtchn_from_irq(irq);
	int cpu;

	mtx_lock_spin(&irq_mapping_update_lock);

	if ((--irq_bindcount[irq] == 0) && VALID_EVTCHN(evtchn)) {
		close.port = evtchn;
		HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);

		switch (type_from_irq(irq)) {
		case IRQT_VIRQ:
			cpu = cpu_from_evtchn(evtchn);
			pcpu_find(cpu)->pc_virq_to_irq[index_from_irq(irq)] = -1;
			break;
		case IRQT_IPI:
			cpu = cpu_from_evtchn(evtchn);
			pcpu_find(cpu)->pc_ipi_to_irq[index_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;
		irq_info[irq] = IRQ_UNBOUND;
	}

	mtx_unlock_spin(&irq_mapping_update_lock);
}

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

	spin_lock(&irq_mapping_update_lock);

	if ((irq = per_cpu(ipi_to_irq, cpu)[ipi]) == -1) {
		if ((irq = find_unbound_irq()) < 0)
			goto out;

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

		evtchn_to_irq[evtchn] = irq;
		irq_info[irq] = mk_irq_info(IRQT_IPI, ipi, evtchn);

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

		bind_evtchn_to_cpu(evtchn, cpu);
	}

	irq_bindcount[irq]++;

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

static int evtchn_bind_to_user(struct per_user_data *u, int port)
{
	int rc = 0;

	/*
	 * Ports are never reused, so every caller should pass in a
	 * unique port.
	 *
	 * (Locking not necessary because we haven't registered the
	 * interrupt handler yet, and our caller has already
	 * serialized bind operations.)
	 */
	BUG_ON(get_port_user(port) != NULL);
	set_port_user(port, u);
	set_port_enabled(port, true); /* start enabled */

	rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED,
				       u->name, (void *)(unsigned long)port);
	if (rc >= 0)
		rc = evtchn_make_refcounted(port);
	else {
		/* bind failed, should close the port now */
		struct evtchn_close close;
		close.port = port;
		if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
			BUG();
		set_port_user(port, NULL);
	}

	return rc;
}

static int evtchn_release(struct inode *inode, struct file *filp)
{
	int i;
	struct per_user_data *u = filp->private_data;
	struct evtchn_close close;

	spin_lock_irq(&port_user_lock);

	free_page((unsigned long)u->ring);

	for (i = 0; i < NR_EVENT_CHANNELS; i++) {
		int ret;
		if (port_user[i] != u)
			continue;

		port_user[i] = NULL;
		mask_evtchn(i);
		rebind_evtchn_to_cpu(i, 0);

		close.port = i;
		ret = HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);
		BUG_ON(ret);
	}

	spin_unlock_irq(&port_user_lock);

	kfree(u);

	return 0;
}

void rebind_evtchn_to_cpu(int port, unsigned int cpu)
{
	struct evtchn_bind_vcpu ebv = { .port = port, .vcpu = cpu };
	int masked;

	masked = test_and_set_evtchn_mask(port);
	if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_vcpu, &ebv) == 0)
		bind_evtchn_to_cpu(port, cpu);
	if (!masked)
		unmask_evtchn(port);
}

static int bind_listening_port_to_irq(unsigned int remote_domain)
{
	struct evtchn_alloc_unbound alloc_unbound;
	int err;

	alloc_unbound.dom        = DOMID_SELF;
	alloc_unbound.remote_dom = remote_domain;

	err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
					  &alloc_unbound);

	return err ? : bind_local_port_to_irq(alloc_unbound.port);
}

void unbind_evtchn(evtchn_port_t port)
{
    struct evtchn_close close;
    int rc;

    mask_evtchn(port);
    clear_evtchn(port);

    close.port = port;
    rc = HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);
    if ( rc )
        printk("WARN: close_port %s failed rc=%d. ignored\n", port, rc);
}

/**
 * Free an existing event channel. Returns 0 on success or -errno on error.
 */
int xenbus_free_evtchn(struct xenbus_device *dev, int port)
{
	struct evtchn_close close;
	int err;

	close.port = port;

	err = HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);
	if (err)
		xenbus_dev_error(dev, err, "freeing event channel %d", port);

	return err;
}

int gnt_init(void)
{
	int mfn;
	int err;
	struct as_sring *sring;

	struct evtchn_alloc_unbound alloc_unbound;
	printk(KERN_INFO "gnt_init\n");

	page =  __get_free_pages(GFP_KERNEL, 0);
	if (page == 0) {
		printk(KERN_DEBUG "\nxen:DomU:could not get free page");
		return 0;
	}

	sring = (struct as_sring *)page;
	SHARED_RING_INIT(sring);
	FRONT_RING_INIT(&(info.ring), sring, PAGE_SIZE);
	mfn = virt_to_mfn(page);

	printk(KERN_INFO "grant foreign access\n");
	info.gref = gnttab_grant_foreign_access(DOM0_ID, mfn, 0);
	if (info.gref < 0) {
		printk(KERN_DEBUG "\nxen:could not grant foreign access");
		free_page((unsigned long)page);
		info.ring.sring = NULL;
		return 0;
	}
	printk(KERN_DEBUG "\n gref = %d", info.gref);
	alloc_unbound.dom = DOMID_SELF;
	alloc_unbound.remote_dom = DOM0_ID;
	err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound, &alloc_unbound);
	if (err) {
		printk(KERN_DEBUG "\nalloc unbound port failure");
		return err;
	}

	err = bind_evtchn_to_irqhandler(alloc_unbound.port, as_int, 0, "xen-eg", &info);
	if (err < 0) {
		printk(KERN_DEBUG "\nbind evtchn to irqhandler failure");
		return err;
	}

	info.irq = err;
	info.port = alloc_unbound.port;
	printk(KERN_DEBUG " interrupt = %d, local_port = %d", info.irq, info.port);
	printk("...\n...");
	create_procfs_entry();
	return 0;
}

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_local_port_to_irq(bind_interdomain.local_port);
}

int evtchn_alloc_unbound(uint32_t pal, void *handler, void *data,
		evtchn_port_t *port) {
	int rc;
	evtchn_alloc_unbound_t op;
	op.dom = DOMID_SELF;
	op.remote_dom = pal;

	rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound, &op);
	if (rc) {
		printk("ERROR: alloc_unbound failed with rc=%d", rc);
		return rc;
	}
	*port = bind_evtchn((uint32_t) op.port, handler, data);
	return rc;
}

int
xenbus_free_evtchn(device_t dev, evtchn_port_t port)
{
	struct evtchn_close close;
	int err;

	close.port = port;

	err = HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);
	if (err) {
		xenbus_dev_error(dev, -err, "freeing event channel %d", port);
		return (-err);
	}
	return (0);
}

int xenbus_conn(domid_t remote_dom, unsigned long *grant_ref, evtchn_port_t *local_port)
{
	struct evtchn_alloc_unbound alloc_unbound;
	int rc, rc2;

	BUG_ON(atomic_read(&xenbus_xsd_state) != XENBUS_XSD_FOREIGN_INIT);
	BUG_ON(!is_initial_xendomain());

#if defined(CONFIG_PROC_FS) && defined(CONFIG_XEN_PRIVILEGED_GUEST)
	remove_xen_proc_entry("xsd_kva");
	remove_xen_proc_entry("xsd_port");
#endif

	rc = xb_free_port(xen_store_evtchn);
	if (rc != 0)
		goto fail0;

	alloc_unbound.dom = DOMID_SELF;
	alloc_unbound.remote_dom = remote_dom;
	rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
	                                 &alloc_unbound);
	if (rc != 0)
		goto fail0;
	*local_port = xen_store_evtchn = alloc_unbound.port;

	/* keep the old page (xen_store_mfn, xen_store_interface) */
	rc = gnttab_grant_foreign_access(remote_dom, xen_store_mfn,
	                                 GTF_permit_access);
	if (rc < 0)
		goto fail1;
	*grant_ref = rc;

	rc = xb_init_comms();
	if (rc != 0)
		goto fail1;

	return 0;

fail1:
	rc2 = xb_free_port(xen_store_evtchn);
	if (rc2 != 0)
		printk(KERN_WARNING
		       "XENBUS: Error freeing xenstore event channel: %d\n",
		       rc2);
fail0:
	xen_store_evtchn = -1;
	return rc;
}

int evtchn_alloc_unbound(domid_t pal, evtchn_port_t *port)
{
    int rc;

    evtchn_alloc_unbound_t op;
    op.dom = DOMID_SELF;
    op.remote_dom = pal;
    rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound, &op);
    if ( rc )
    {
        printk("ERROR: alloc_unbound failed with rc=%d", rc);
	return rc;
    }
    *port = op.port;
    return rc;
}

int evtchn_bind_interdomain(domid_t pal, evtchn_port_t remote_port,
			    evtchn_port_t *local_port)
{
    int rc;
    evtchn_bind_interdomain_t op;
    op.remote_dom = pal;
    op.remote_port = remote_port;
    rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain, &op);
    if ( rc )
    {
        printk("ERROR: bind_interdomain failed with rc=%d", rc);
		return rc;
    }
    *local_port = op.local_port;
    return rc;
}