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Subject: Re: [Xen-devel] [PATCH 01/11] xen/arm: use dma-noncoherent.h calls
 for xen-swiotlb cache maintainance
To:     Christoph Hellwig <hch@lst.de>,
        Stefano Stabellini <sstabellini@kernel.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc:     xen-devel@lists.xenproject.org, iommu@lists.linux-foundation.org,
        x86@kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org
References: <20190816130013.31154-1-hch@lst.de>
 <20190816130013.31154-2-hch@lst.de>
From:   Julien Grall <julien.grall@arm.com>
Message-ID: <65248838-f273-6097-22f4-e5809078ddba@arm.com>
Date:   Mon, 19 Aug 2019 12:45:17 +0100
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Hi Christoph,

On 8/16/19 2:00 PM, Christoph Hellwig wrote:
> +static inline void xen_dma_map_page(struct device *hwdev, struct page *page,
> +	     dma_addr_t dev_addr, unsigned long offset, size_t size,
> +	     enum dma_data_direction dir, unsigned long attrs)
> +{
> +	unsigned long page_pfn = page_to_xen_pfn(page);
> +	unsigned long dev_pfn = XEN_PFN_DOWN(dev_addr);
> +	unsigned long compound_pages =
> +		(1<<compound_order(page)) * XEN_PFN_PER_PAGE;
> +	bool local = (page_pfn <= dev_pfn) &&
> +		(dev_pfn - page_pfn < compound_pages);
> +

The Arm version as a comment here. Could we retain it?

> +	if (local)
> +		dma_direct_map_page(hwdev, page, offset, size, dir, attrs);
> +	else
> +		__xen_dma_map_page(hwdev, page, dev_addr, offset, size, dir, attrs);
> +}
> +

Cheers,

-- 
Julien Grall