Re: [PATCH v2 2/2] iommu/sva: Remove mm parameter from SVA bind API

[Christoph Hellwig]

>   *
>   * Returns 0 on success and < 0 on error.
> @@ -28,6 +28,9 @@ int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max)
>  	int ret = 0;
>  	ioasid_t pasid;
>  
> +	if (mm != current->mm)
> +		return -EINVAL;
> +

Why not remove the parameter entirely?

> @@ -2989,8 +2990,11 @@ iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, unsigned int fla
>  		return ERR_PTR(-ENODEV);
>  
>  	/* Supervisor SVA does not need the current mm */
> -	if ((flags & IOMMU_SVA_BIND_SUPERVISOR) && mm)
> -		return ERR_PTR(-EINVAL);
> +	if (!(flags & IOMMU_SVA_BIND_SUPERVISOR)) {
> +		mm = get_task_mm(current);
> +		if (!mm)
> +			return ERR_PTR(-EINVAL);
> +	}

I don't see why we need the reference.  I think we should just stop
passing the mm to ->sva_bind and let the low-level driver deal with
any reference to current->mm where needed.