Re: [RFC PATCH v3 06/12] iommu: Split 'addr_merge' argument to iommu_pgsize() into separate parts

[Will Deacon <will@kernel.org>]

On Mon, Apr 05, 2021 at 12:11:06PM -0700, Isaac J. Manjarres wrote:
> From: Will Deacon <will@kernel.org>
> 
> The 'addr_merge' parameter to iommu_pgsize() is a fabricated address
> intended to describe the alignment requirements to consider when
> choosing an appropriate page size. On the iommu_map() path, this address
> is the logical OR of the virtual and physical addresses.
> 
> Subsequent improvements to iommu_pgsize() will need to check the
> alignment of the virtual and physical components of 'addr_merge'
> independently, so pass them in as separate parameters and reconstruct
> 'addr_merge' locally.
> 
> No functional change.
> 
> Signed-off-by: Will Deacon <will@kernel.org>
> Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
> ---
>  drivers/iommu/iommu.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 9006397b6604..a3bbf7e310b0 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -2357,12 +2357,13 @@ phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova)
>  }
>  EXPORT_SYMBOL_GPL(iommu_iova_to_phys);
>  
> -static size_t iommu_pgsize(struct iommu_domain *domain,
> -			   unsigned long addr_merge, size_t size)
> +static size_t iommu_pgsize(struct iommu_domain *domain, unsigned long iova,
> +			   phys_addr_t paddr, size_t size)
>  {
>  	unsigned int pgsize_idx;
>  	unsigned long pgsizes;
>  	size_t pgsize;
> +	phys_addr_t addr_merge = paddr | iova;

Huh, so this was 'unsigned long' before and, given that the pgsize_bitmap
on the domain is also unsigned long, then I think that's fine. So using
that would mean you don't need GENMASK_ULL for this guy either.

Will

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