vfio_pci: Allow regions to add own capabilities

VFIO regions already support region capabilities with a limited set of
fields. However the subdriver might have to report to the userspace
additional bits.

This adds an add_capability() hook to vfio_pci_regops.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

drivers/vfio/pci/vfio_pci.c

@@ -750,6 +750,12 @@ static long vfio_pci_ioctl(void *device_data,
 			if (ret)
 				return ret;
 
+			if (vdev->region[i].ops->add_capability) {
+				ret = vdev->region[i].ops->add_capability(vdev,
+						&vdev->region[i], &caps);
+				if (ret)
+					return ret;
+			}
 		}
 		}
 

drivers/vfio/pci/vfio_pci_private.h

@@ -62,6 +62,9 @@ struct vfio_pci_regops {
 	int	(*mmap)(struct vfio_pci_device *vdev,
 			struct vfio_pci_region *region,
 			struct vm_area_struct *vma);
+	int	(*add_capability)(struct vfio_pci_device *vdev,
+				  struct vfio_pci_region *region,
+				  struct vfio_info_cap *caps);
 };
 
 struct vfio_pci_region {