[PATCH v2 6/9] vfio/mdev: Add mdev available instance checking to the core

[Cornelia Huck]

On Thu, Sep 09 2021, Jason Gunthorpe <jgg at nvidia.com> wrote:

> Many of the mdev drivers use a simple counter for keeping track of the
> available instances. Move this code to the core code and store the counter
> in the mdev_type. Implement it using correct locking, fixing mdpy.
>
> Drivers provide a get_available() callback to set the number of available
> instances for their mtypes which is fixed at registration time. The core
> provides a standard sysfs attribute to return the available_instances.

So, according to the documentation, available_instances is
mandatory. This means that drivers either need to provide get_available
or implement their own version of the attribute. I think we want to
update vfio-mediated-device.rst as well?

>
> Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
> ---
>  drivers/s390/cio/vfio_ccw_drv.c       |  1 -
>  drivers/s390/cio/vfio_ccw_ops.c       | 26 ++++++-------------
>  drivers/s390/cio/vfio_ccw_private.h   |  2 --
>  drivers/s390/crypto/vfio_ap_ops.c     | 32 ++++++-----------------
>  drivers/s390/crypto/vfio_ap_private.h |  2 --
>  drivers/vfio/mdev/mdev_core.c         | 11 +++++++-
>  drivers/vfio/mdev/mdev_private.h      |  2 ++
>  drivers/vfio/mdev/mdev_sysfs.c        | 37 +++++++++++++++++++++++++++
>  include/linux/mdev.h                  |  2 ++
>  samples/vfio-mdev/mdpy.c              | 22 +++++-----------
>  10 files changed, 73 insertions(+), 64 deletions(-)

Otherwise, looks good.