Function xen_hvm_set_callback

freebsd/x86/xen/hvm.c:249–303

* Tell the hypervisor how to contact us for event channel callbacks. */

 * Tell the hypervisor how to contact us for event channel callbacks.
 */
void
xen_hvm_set_callback(device_t dev)
{
	struct xen_hvm_param xhp;
	int irq;

	if (xen_vector_callback_enabled)
		return;

	xhp.domid = DOMID_SELF;
	xhp.index = HVM_PARAM_CALLBACK_IRQ;
	if (xen_feature(XENFEAT_hvm_callback_vector) != 0) {
		int error;

		error = set_percpu_callback(0);
		if (error == 0) {
			xen_evtchn_needs_ack = true;
			/* Trick toolstack to think we are enlightened */
			xhp.value = 1;
		} else
			xhp.value = HVM_CALLBACK_VECTOR(IDT_EVTCHN);
		error = HYPERVISOR_hvm_op(HVMOP_set_param, &xhp);
		if (error == 0) {
			xen_vector_callback_enabled = 1;
			return;
		} else if (xen_evtchn_needs_ack)
			panic("Unable to setup fake HVM param: %d", error);

		printf("Xen HVM callback vector registration failed (%d). "
		    "Falling back to emulated device interrupt\n", error);
	}
	xen_vector_callback_enabled = 0;
	if (dev == NULL) {
		/*
		 * Called from early boot or resume.
		 * xenpci will invoke us again later.
		 */
		return;
	}

	irq = pci_get_irq(dev);
	if (irq < 16) {
		xhp.value = HVM_CALLBACK_GSI(irq);
	} else {
		u_int slot;
		u_int pin;

		slot = pci_get_slot(dev);
		pin = pci_get_intpin(dev) - 1;
		xhp.value = HVM_CALLBACK_PCI_INTX(slot, pin);
	}

	if (HYPERVISOR_hvm_op(HVMOP_set_param, &xhp) != 0)
		panic("Can't set evtchn callback");
}

#define	XEN_MAGIC_IOPORT 0x10
enum {