vfio/pci: Intel IGD OpRegion support

This is the first consumer of vfio device specific resource support,
providing read-only access to the OpRegion for Intel graphics devices.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index b1e4032..19f7699 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -122,4 +122,12 @@
 					unsigned int type, unsigned int subtype,
 					const struct vfio_pci_regops *ops,
 					size_t size, u32 flags, void *data);
+#ifdef CONFIG_VFIO_PCI_IGD
+extern int vfio_pci_igd_opregion_init(struct vfio_pci_device *vdev);
+#else
+static inline int vfio_pci_igd_opregion_init(struct vfio_pci_device *vdev)
+{
+	return -ENODEV;
+}
+#endif
 #endif /* VFIO_PCI_PRIVATE_H */