Re: [Patch v8 04/10] vfio/type1: Support binding guest page tables to PASID

[Jason Gunthorpe <jgg@nvidia.com>]

On Wed, Mar 03, 2021 at 04:35:39AM +0800, Liu Yi L wrote:
>  
> +static int vfio_dev_bind_gpasid_fn(struct device *dev, void *data)
> +{
> +	struct domain_capsule *dc = (struct domain_capsule *)data;
> +	unsigned long arg = *(unsigned long *)dc->data;
> +
> +	return iommu_uapi_sva_bind_gpasid(dc->domain, dev,
> +					  (void __user *)arg);

This arg buisness is really tortured. The type should be set at the
ioctl, not constantly passed down as unsigned long or worse void *.

And why is this passing a __user pointer deep into an iommu_* API??

> +/**
> + * VFIO_IOMMU_NESTING_OP - _IOW(VFIO_TYPE, VFIO_BASE + 18,
> + *				struct vfio_iommu_type1_nesting_op)
> + *
> + * This interface allows userspace to utilize the nesting IOMMU
> + * capabilities as reported in VFIO_IOMMU_TYPE1_INFO_CAP_NESTING
> + * cap through VFIO_IOMMU_GET_INFO. For platforms which require
> + * system wide PASID, PASID will be allocated by VFIO_IOMMU_PASID
> + * _REQUEST.
> + *
> + * @data[] types defined for each op:
> + * +=================+===============================================+
> + * | NESTING OP      |      @data[]                                  |
> + * +=================+===============================================+
> + * | BIND_PGTBL      |      struct iommu_gpasid_bind_data            |
> + * +-----------------+-----------------------------------------------+
> + * | UNBIND_PGTBL    |      struct iommu_gpasid_bind_data            |
> + *
> +-----------------+-----------------------------------------------+

If the type is known why does the struct have a flex array?

Jason