Subject: Re: [PATCH v2 01/30] iommu: introduce iova_to_phys_length in iommu_domain_ops

From: Jason Gunthorpe <[email-masked]>
Date: Tue, 2 Jun 2026 22:08:36 -0300

On Tue, Jun 02, 2026 at 06:46:08PM +0800, Guanghui Feng wrote:
> +/**
> + * iommu_iova_to_phys_length - Translate IOVA and return mapping page size
> + * @domain: IOMMU domain to query
> + * @iova: IO virtual address to translate
> + * @mapped_length: Output parameter for the PTE page size (e.g. 4KB/2MB/1GB)
> + *
> + * Like iommu_iova_to_phys() but additionally returns the page size of the
> + * PTE mapping at @iova through @mapped_length.
> + *
> + * Return: The physical address for the given IOVA, or PHYS_ADDR_MAX if no translation.
> + */
> +phys_addr_t iommu_iova_to_phys_length(struct iommu_domain *domain,
> +				       dma_addr_t iova,
> +				       size_t *mapped_length)
>  {
> +	if (mapped_length)
> +		*mapped_length = 0;
> +
>  	if (domain->type == IOMMU_DOMAIN_IDENTITY)
>  		return iova;

This doesn't seem right. It needs to return a mapped_length of
something that is not zero..

> -	if (domain->type == IOMMU_DOMAIN_BLOCKED)
> -		return 0;
> +	if (!domain->ops->iova_to_phys_length) {
> +		/* Fallback to legacy iova_to_phys without length info */
> +		if (domain->ops->iova_to_phys) {
> +			phys_addr_t phys = domain->ops->iova_to_phys(domain, iova);
> +			if (phys && mapped_length)
> +				*mapped_length = PAGE_SIZE;
> +			return phys ? phys : PHYS_ADDR_MAX;
> +		}

Follow success oriented flow..

Jason