Re: [PATCH v4 10/18] iommu/amd: Add domain_alloc_user based domain allocation

[Jason Gunthorpe <jgg@nvidia.com>]

On Wed, Oct 18, 2023 at 09:27:07PM +0100, Joao Martins wrote:
> -static struct iommu_domain *amd_iommu_domain_alloc(unsigned type)
> +static struct iommu_domain *do_iommu_domain_alloc(unsigned int type,
> +						  struct device *dev,
> +						  u32 flags)
>  {
>  	struct protection_domain *domain;
> +	struct amd_iommu *iommu = NULL;
> +
> +	if (dev) {
> +		iommu = rlookup_amd_iommu(dev);
> +		if (!iommu)
> +			return ERR_PTR(-ENODEV);
> +	}
>  
>  	/*
>  	 * Since DTE[Mode]=0 is prohibited on SNP-enabled system,
>  	 * default to use IOMMU_DOMAIN_DMA[_FQ].
>  	 */
>  	if (amd_iommu_snp_en && (type == IOMMU_DOMAIN_IDENTITY))
> -		return NULL;
> +		return ERR_PTR(-EINVAL);
>  
>  	domain = protection_domain_alloc(type);
>  	if (!domain)
> -		return NULL;
> +		return ERR_PTR(-ENOMEM);
>  
>  	domain->domain.geometry.aperture_start = 0;
>  	domain->domain.geometry.aperture_end   = dma_max_address();
>  	domain->domain.geometry.force_aperture = true;
>  
> +	if (iommu) {
> +		domain->domain.type = type;
> +		domain->domain.pgsize_bitmap =
> +			iommu->iommu.ops->pgsize_bitmap;
> +		domain->domain.ops =
> +			iommu->iommu.ops->default_domain_ops;
> +	}
> +
>  	return &domain->domain;
>  }

In the end this is probably not enough refactoring, but this driver
needs so much work we should just wait till the already written series
get merged.

eg domain_alloc_paging should just invoke domain_alloc_user with some
null arguments if the driver is constructed this way

> +static struct iommu_domain *amd_iommu_domain_alloc_user(struct device *dev,
> +							u32 flags)
> +{
> +	unsigned int type = IOMMU_DOMAIN_UNMANAGED;
> +
> +	if (flags & IOMMU_HWPT_ALLOC_NEST_PARENT)
> +		return ERR_PTR(-EOPNOTSUPP);

This should be written as a list of flags the driver *supports* not
that it rejects

if (flags)
	return ERR_PTR(-EOPNOTSUPP);

Jason