On Mon, Mar 08, 2021 at 02:47:40PM -0700, Alex Williamson wrote:

Rather than an errno, return a pointer to the opaque vfio_device
to allow the bus driver to call into vfio-core without additional
lookups and references.  Note that bus drivers are still required
to use vfio_del_group_dev() to teardown the vfio_device.

Signed-off-by: Alex Williamson <redacted>

This looks like it is superseded by the

  vfio: Split creation of a vfio_device into init and register ops

patch from Jason, which provides a much nicer API.