[PATCH 07/10] vfio-iommufd: Support iommufd for physical VFIO devices

[Tian, Kevin]

> From: Jason Gunthorpe <jgg at nvidia.com>
> Sent: Wednesday, October 26, 2022 2:51 AM
> 
> +int vfio_iommufd_bind(struct vfio_device *vdev, struct iommufd_ctx *ictx)
> +{
> +	u32 ioas_id;
> +	u32 device_id;
> +	int ret;
> +
> +	lockdep_assert_held(&vdev->dev_set->lock);
> +
> +	/*
> +	 * If the driver doesn't provide this op then it means the device does
> +	 * not do DMA at all. So nothing to do.
> +	 */
> +	if (!vdev->ops->bind_iommufd)
> +		return 0;

Nothing to do or return -EOPNOTSUPP?

> +
> +	ret = vdev->ops->bind_iommufd(vdev, ictx, &device_id);
> +	if (ret)
> +		return ret;
> +
> +	if (vdev->ops->attach_ioas) {

__vfio_register_dev() already verifies that all three callbacks must
co-exist. Then no need to check it again here and later.

> +void vfio_iommufd_unbind(struct vfio_device *vdev)
> +{
> +	lockdep_assert_held(&vdev->dev_set->lock);
> +
> +	if (!vdev->iommufd_device)
> +		return;

there is no iommufd_device in the emulated path...