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iommufd/iova_bitmap: Consider page offset for the pages to be pinned
For small bitmaps that aren't PAGE_SIZE aligned *and* that are less than
512 pages in bitmap length, use an extra page to be able to cover the
entire range e.g. [1M..3G] which would be iterated more efficiently in a
single iteration, rather than two.
Fixes: b058ea3ab5
("vfio/iova_bitmap: refactor iova_bitmap_set() to better handle page boundaries")
Link: https://lore.kernel.org/r/20240202133415.23819-10-joao.m.martins@oracle.com
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Tested-by: Avihai Horon <avihaih@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
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@ -178,18 +178,19 @@ static int iova_bitmap_get(struct iova_bitmap *bitmap)
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bitmap->mapped_base_index) *
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sizeof(*bitmap->bitmap), PAGE_SIZE);
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/*
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* We always cap at max number of 'struct page' a base page can fit.
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* This is, for example, on x86 means 2M of bitmap data max.
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*/
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npages = min(npages, PAGE_SIZE / sizeof(struct page *));
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/*
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* Bitmap address to be pinned is calculated via pointer arithmetic
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* with bitmap u64 word index.
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*/
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addr = bitmap->bitmap + bitmap->mapped_base_index;
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/*
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* We always cap at max number of 'struct page' a base page can fit.
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* This is, for example, on x86 means 2M of bitmap data max.
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*/
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npages = min(npages + !!offset_in_page(addr),
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PAGE_SIZE / sizeof(struct page *));
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ret = pin_user_pages_fast((unsigned long)addr, npages,
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FOLL_WRITE, mapped->pages);
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if (ret <= 0)
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