xen: map MSIs into pirqs

Map MSIs into pirqs, writing 0 in the MSI vector data field and the pirq
number in the MSI destination id field.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/include/xen/events.h b/include/xen/events.h
index deec8fa..0c58db6 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -72,6 +72,8 @@
  * usual. */
 int xen_allocate_pirq(unsigned gsi, int shareable, char *name);
 int xen_map_pirq_gsi(unsigned pirq, unsigned gsi, int shareable, char *name);
+/* Allocate an irq and a pirq to be used with MSIs. */
+void xen_allocate_pirq_msi(char *name, int *irq, int *pirq);
 
 /* De-allocates the above mentioned physical interrupt. */
 int xen_destroy_irq(int irq);