linux-kernel - Re: [PATCH v7 06/15] iommu: Split 'addr_merge' argument to iommu

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Message-ID: <21ba382a-8add-5872-13c9-6f97698a594d@linux.intel.com>
Date:   Thu, 17 Jun 2021 15:17:10 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Georgi Djakov <quic_c_gdjako@...cinc.com>, will@...nel.org,
        robin.murphy@....com
Cc:     baolu.lu@...ux.intel.com, joro@...tes.org, isaacm@...eaurora.org,
        pratikp@...eaurora.org, iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        djakov@...nel.org
Subject: Re: [PATCH v7 06/15] iommu: Split 'addr_merge' argument to
 iommu_pgsize() into separate parts

On 6/16/21 9:38 PM, Georgi Djakov wrote:
> From: Will Deacon <will@...nel.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@...nel.org>
> Signed-off-by: Isaac J. Manjarres <isaacm@...eaurora.org>
> Signed-off-by: Georgi Djakov <quic_c_gdjako@...cinc.com>
> ---
>   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 80e471ada358..80e14c139d40 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -2375,12 +2375,13 @@ 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;
> +	unsigned long addr_merge = paddr | iova;
>   
>   	/* Page sizes supported by the hardware and small enough for @size */
>   	pgsizes = domain->pgsize_bitmap & GENMASK(__fls(size), 0);
> @@ -2433,7 +2434,7 @@ static int __iommu_map(struct iommu_domain *domain, unsigned long iova,
>   	pr_debug("map: iova 0x%lx pa %pa size 0x%zx\n", iova, &paddr, size);
>   
>   	while (size) {
> -		size_t pgsize = iommu_pgsize(domain, iova | paddr, size);
> +		size_t pgsize = iommu_pgsize(domain, iova, paddr, size);
>   
>   		pr_debug("mapping: iova 0x%lx pa %pa pgsize 0x%zx\n",
>   			 iova, &paddr, pgsize);
> @@ -2521,8 +2522,9 @@ static size_t __iommu_unmap(struct iommu_domain *domain,
>   	 * or we hit an area that isn't mapped.
>   	 */
>   	while (unmapped < size) {
> -		size_t pgsize = iommu_pgsize(domain, iova, size - unmapped);
> +		size_t pgsize;
>   
> +		pgsize = iommu_pgsize(domain, iova, iova, size - unmapped);
>   		unmapped_page = ops->unmap(domain, iova, pgsize, iotlb_gather);
>   		if (!unmapped_page)
>   			break;
> 

Reviewed-by: Lu Baolu <baolu.lu@...ux.intel.com>

Best regards,
baolu