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Subject: Re: [PATCH v6 4/7] dma-iommu: fold _swiotlb helpers into callers
To:     David Stevens <stevensd@chromium.org>,
        Christoph Hellwig <hch@lst.de>
Cc:     Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        Tom Murphy <murphyt7@tcd.ie>, iommu@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org
References: <20210817013852.3222824-1-stevensd@google.com>
 <20210817013852.3222824-5-stevensd@google.com>
From:   Robin Murphy <robin.murphy@arm.com>
Message-ID: <3cc9eb26-3225-ed2a-8784-cdc2119970e9@arm.com>
Date:   Thu, 19 Aug 2021 10:00:18 +0100
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On 2021-08-17 02:38, David Stevens wrote:
> From: David Stevens <stevensd@chromium.org>
> 
> Fold the _swiotlb helper functions into the respective _page functions,
> since recent fixes have moved all logic from the _page functions to the
> _swiotlb functions.

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: David Stevens <stevensd@chromium.org>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
>   drivers/iommu/dma-iommu.c | 135 +++++++++++++++++---------------------
>   1 file changed, 59 insertions(+), 76 deletions(-)
> 
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 5dd2c517dbf5..8152efada8b2 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -493,26 +493,6 @@ static void __iommu_dma_unmap(struct device *dev, dma_addr_t dma_addr,
>   	iommu_dma_free_iova(cookie, dma_addr, size, iotlb_gather.freelist);
>   }
>   
> -static void __iommu_dma_unmap_swiotlb(struct device *dev, dma_addr_t dma_addr,
> -		size_t size, enum dma_data_direction dir,
> -		unsigned long attrs)
> -{
> -	struct iommu_domain *domain = iommu_get_dma_domain(dev);
> -	phys_addr_t phys;
> -
> -	phys = iommu_iova_to_phys(domain, dma_addr);
> -	if (WARN_ON(!phys))
> -		return;
> -
> -	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) && !dev_is_dma_coherent(dev))
> -		arch_sync_dma_for_cpu(phys, size, dir);
> -
> -	__iommu_dma_unmap(dev, dma_addr, size);
> -
> -	if (unlikely(is_swiotlb_buffer(phys)))
> -		swiotlb_tbl_unmap_single(dev, phys, size, dir, attrs);
> -}
> -
>   static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys,
>   		size_t size, int prot, u64 dma_mask)
>   {
> @@ -539,55 +519,6 @@ static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys,
>   	return iova + iova_off;
>   }
>   
> -static dma_addr_t __iommu_dma_map_swiotlb(struct device *dev, phys_addr_t phys,
> -		size_t org_size, dma_addr_t dma_mask, bool coherent,
> -		enum dma_data_direction dir, unsigned long attrs)
> -{
> -	int prot = dma_info_to_prot(dir, coherent, attrs);
> -	struct iommu_domain *domain = iommu_get_dma_domain(dev);
> -	struct iommu_dma_cookie *cookie = domain->iova_cookie;
> -	struct iova_domain *iovad = &cookie->iovad;
> -	size_t aligned_size = org_size;
> -	void *padding_start;
> -	size_t padding_size;
> -	dma_addr_t iova;
> -
> -	/*
> -	 * If both the physical buffer start address and size are
> -	 * page aligned, we don't need to use a bounce page.
> -	 */
> -	if (IS_ENABLED(CONFIG_SWIOTLB) && dev_is_untrusted(dev) &&
> -	    iova_offset(iovad, phys | org_size)) {
> -		aligned_size = iova_align(iovad, org_size);
> -		phys = swiotlb_tbl_map_single(dev, phys, org_size,
> -					      aligned_size, dir, attrs);
> -
> -		if (phys == DMA_MAPPING_ERROR)
> -			return DMA_MAPPING_ERROR;
> -
> -		/* Cleanup the padding area. */
> -		padding_start = phys_to_virt(phys);
> -		padding_size = aligned_size;
> -
> -		if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
> -		    (dir == DMA_TO_DEVICE ||
> -		     dir == DMA_BIDIRECTIONAL)) {
> -			padding_start += org_size;
> -			padding_size -= org_size;
> -		}
> -
> -		memset(padding_start, 0, padding_size);
> -	}
> -
> -	if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
> -		arch_sync_dma_for_device(phys, org_size, dir);
> -
> -	iova = __iommu_dma_map(dev, phys, aligned_size, prot, dma_mask);
> -	if (iova == DMA_MAPPING_ERROR && is_swiotlb_buffer(phys))
> -		swiotlb_tbl_unmap_single(dev, phys, org_size, dir, attrs);
> -	return iova;
> -}
> -
>   static void __iommu_dma_free_pages(struct page **pages, int count)
>   {
>   	while (count--)
> @@ -848,15 +779,68 @@ static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
>   {
>   	phys_addr_t phys = page_to_phys(page) + offset;
>   	bool coherent = dev_is_dma_coherent(dev);
> +	int prot = dma_info_to_prot(dir, coherent, attrs);
> +	struct iommu_domain *domain = iommu_get_dma_domain(dev);
> +	struct iommu_dma_cookie *cookie = domain->iova_cookie;
> +	struct iova_domain *iovad = &cookie->iovad;
> +	size_t aligned_size = size;
> +	dma_addr_t iova, dma_mask = dma_get_mask(dev);
> +
> +	/*
> +	 * If both the physical buffer start address and size are
> +	 * page aligned, we don't need to use a bounce page.
> +	 */
> +	if (IS_ENABLED(CONFIG_SWIOTLB) && dev_is_untrusted(dev) &&
> +	    iova_offset(iovad, phys | size)) {
> +		void *padding_start;
> +		size_t padding_size;
> +
> +		aligned_size = iova_align(iovad, size);
> +		phys = swiotlb_tbl_map_single(dev, phys, size,
> +					      aligned_size, dir, attrs);
> +
> +		if (phys == DMA_MAPPING_ERROR)
> +			return DMA_MAPPING_ERROR;
>   
> -	return __iommu_dma_map_swiotlb(dev, phys, size, dma_get_mask(dev),
> -			coherent, dir, attrs);
> +		/* Cleanup the padding area. */
> +		padding_start = phys_to_virt(phys);
> +		padding_size = aligned_size;
> +
> +		if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
> +		    (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)) {
> +			padding_start += size;
> +			padding_size -= size;
> +		}
> +
> +		memset(padding_start, 0, padding_size);
> +	}
> +
> +	if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
> +		arch_sync_dma_for_device(phys, size, dir);
> +
> +	iova = __iommu_dma_map(dev, phys, aligned_size, prot, dma_mask);
> +	if (iova == DMA_MAPPING_ERROR && is_swiotlb_buffer(phys))
> +		swiotlb_tbl_unmap_single(dev, phys, size, dir, attrs);
> +	return iova;
>   }
>   
>   static void iommu_dma_unmap_page(struct device *dev, dma_addr_t dma_handle,
>   		size_t size, enum dma_data_direction dir, unsigned long attrs)
>   {
> -	__iommu_dma_unmap_swiotlb(dev, dma_handle, size, dir, attrs);
> +	struct iommu_domain *domain = iommu_get_dma_domain(dev);
> +	phys_addr_t phys;
> +
> +	phys = iommu_iova_to_phys(domain, dma_handle);
> +	if (WARN_ON(!phys))
> +		return;
> +
> +	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) && !dev_is_dma_coherent(dev))
> +		arch_sync_dma_for_cpu(phys, size, dir);
> +
> +	__iommu_dma_unmap(dev, dma_handle, size);
> +
> +	if (unlikely(is_swiotlb_buffer(phys)))
> +		swiotlb_tbl_unmap_single(dev, phys, size, dir, attrs);
>   }
>   
>   /*
> @@ -941,7 +925,7 @@ static void iommu_dma_unmap_sg_swiotlb(struct device *dev, struct scatterlist *s
>   	int i;
>   
>   	for_each_sg(sg, s, nents, i)
> -		__iommu_dma_unmap_swiotlb(dev, sg_dma_address(s),
> +		iommu_dma_unmap_page(dev, sg_dma_address(s),
>   				sg_dma_len(s), dir, attrs);
>   }
>   
> @@ -952,9 +936,8 @@ static int iommu_dma_map_sg_swiotlb(struct device *dev, struct scatterlist *sg,
>   	int i;
>   
>   	for_each_sg(sg, s, nents, i) {
> -		sg_dma_address(s) = __iommu_dma_map_swiotlb(dev, sg_phys(s),
> -				s->length, dma_get_mask(dev),
> -				dev_is_dma_coherent(dev), dir, attrs);
> +		sg_dma_address(s) = iommu_dma_map_page(dev, sg_page(s),
> +				s->offset, s->length, dir, attrs);
>   		if (sg_dma_address(s) == DMA_MAPPING_ERROR)
>   			goto out_unmap;
>   		sg_dma_len(s) = s->length;
>