On Fri, 12 Mar 2021 20:55:55 -0400
Jason Gunthorpe <jgg@xxxxxxxxxx> wrote:
> This makes the struct vfio_pci_device part of the public interface so it
> can be used with container_of and so forth, as is typical for a Linux
> subystem.
>
> This is the first step to bring some type-safety to the vfio interface by
> allowing the replacement of 'void *' and 'struct device *' inputs with a
> simple and clear 'struct vfio_pci_device *'
>
> For now the self-allocating vfio_add_group_dev() interface is kept so each
> user can be updated as a separate patch.
>
> The expected usage pattern is
>
> driver core probe() function:
> my_device = kzalloc(sizeof(*mydevice));
> vfio_init_group_dev(&my_device->vdev, dev, ops, mydevice);
> /* other driver specific prep */
> vfio_register_group_dev(&my_device->vdev);
> dev_set_drvdata(my_device);
>
> driver core remove() function:
> my_device = dev_get_drvdata(dev);
> vfio_unregister_group_dev(&my_device->vdev);
> /* other driver specific tear down */
> kfree(my_device);
>
> Allowing the driver to be able to use the drvdata and vifo_device to go
s/vifo_device/vfio_device/
> to/from its own data.
>
> The pattern also makes it clear that vfio_register_group_dev() must be
> last in the sequence, as once it is called the core code can immediately
> start calling ops. The init/register gap is provided to allow for the
> driver to do setup before ops can be called and thus avoid races.
>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Reviewed-by: Liu Yi L <yi.l.liu@xxxxxxxxx>
> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> ---
> Documentation/driver-api/vfio.rst | 31 ++++----
> drivers/vfio/vfio.c | 123 ++++++++++++++++--------------
> include/linux/vfio.h | 16 ++++
> 3 files changed, 98 insertions(+), 72 deletions(-)
>
> diff --git a/Documentation/driver-api/vfio.rst b/Documentation/driver-api/vfio.rst
> index f1a4d3c3ba0bb1..d3a02300913a7f 100644
> --- a/Documentation/driver-api/vfio.rst
> +++ b/Documentation/driver-api/vfio.rst
> @@ -249,18 +249,23 @@ VFIO bus driver API
>
> VFIO bus drivers, such as vfio-pci make use of only a few interfaces
> into VFIO core. When devices are bound and unbound to the driver,
> -the driver should call vfio_add_group_dev() and vfio_del_group_dev()
> -respectively::
> -
> - extern int vfio_add_group_dev(struct device *dev,
> - const struct vfio_device_ops *ops,
> - void *device_data);
> -
> - extern void *vfio_del_group_dev(struct device *dev);
> -
> -vfio_add_group_dev() indicates to the core to begin tracking the
> -iommu_group of the specified dev and register the dev as owned by
> -a VFIO bus driver. The driver provides an ops structure for callbacks
> +the driver should call vfio_register_group_dev() and
> +vfio_unregister_group_dev() respectively::
> +
> + void vfio_init_group_dev(struct vfio_device *device,
> + struct device *dev,
> + const struct vfio_device_ops *ops,
> + void *device_data);
> + int vfio_register_group_dev(struct vfio_device *device);
> + void vfio_unregister_group_dev(struct vfio_device *device);
> +
> +The driver should embed the vfio_device in its own structure and call
> +vfio_init_group_dev() to pre-configure it before going to registration.
s/it/that structure/ (I guess?)
> +vfio_register_group_dev() indicates to the core to begin tracking the
> +iommu_group of the specified dev and register the dev as owned by a VFIO bus
> +driver. Once vfio_register_group_dev() returns it is possible for userspace to
> +start accessing the driver, thus the driver should ensure it is completely
> +ready before calling it. The driver provides an ops structure for callbacks
> similar to a file operations structure::
>
> struct vfio_device_ops {
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
