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Re: [PATCH] swiotlb-xen: override common mmap and get_sgtable dma ops
- To: Roman Skakun <rm.skakun@xxxxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx, iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
- From: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
- Date: Fri, 11 Jun 2021 11:19:58 -0400
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- Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>, Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>, Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>, Roman Skakun <roman_skakun@xxxxxxxx>, Andrii Anisov <andrii_anisov@xxxxxxxx>
- Delivery-date: Fri, 11 Jun 2021 15:20:19 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 6/11/21 5:55 AM, Roman Skakun wrote:
>
> +static int
> +xen_swiotlb_dma_mmap(struct device *dev, struct vm_area_struct *vma,
> + void *cpu_addr, dma_addr_t dma_addr, size_t size,
> + unsigned long attrs)
> +{
> + unsigned long user_count = vma_pages(vma);
> + unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
> + unsigned long off = vma->vm_pgoff;
> + struct page *page;
> +
> + if (is_vmalloc_addr(cpu_addr))
> + page = vmalloc_to_page(cpu_addr);
> + else
> + page = virt_to_page(cpu_addr);
> +
> + vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
> +
> + if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
> + return -ENXIO;
> +
> + if (off >= count || user_count > count - off)
> + return -ENXIO;
> +
> + return remap_pfn_range(vma, vma->vm_start,
> + page_to_pfn(page) + vma->vm_pgoff,
> + user_count << PAGE_SHIFT, vma->vm_page_prot);
> +}
I suggest you create a helper for computing page value and then revert
922659ea771b3fd728149262c5ea15608fab9719 and pass result of the helper instead
of cpu_addr. Here and in xen_swiotlb_dma_get_sgtable().
And use this new helper in xen_swiotlb_free_coherent() too. I am curious though
why this was not a problem when Stefano was looking at the problem that
introduced this vmalloc check (i.e. 8b1e868f66076490189a36d984fcce286cdd6295).
Stefano?
-boris
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