vfio: Add external user check extension interface

This lets us check extensions, particularly VFIO_DMA_CC_IOMMU using
the external user interface, allowing KVM to probe IOMMU coherency.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 21271d8df023..512f479d8a50 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1413,6 +1413,12 @@ int vfio_external_user_iommu_id(struct vfio_group *group)
 }
 EXPORT_SYMBOL_GPL(vfio_external_user_iommu_id);
 
+long vfio_external_check_extension(struct vfio_group *group, unsigned long arg)
+{
+        return vfio_ioctl_check_extension(group->container, arg);
+}
+EXPORT_SYMBOL_GPL(vfio_external_check_extension);
+
 /**
  * Module/class support
  */