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vfio/iova_bitmap: refactor iova_bitmap_set() to better handle page boundaries
Commitf38044e5ef
("vfio/iova_bitmap: Fix PAGE_SIZE unaligned bitmaps") had fixed the unaligned bitmaps by capping the remaining iterable set at the start of the bitmap. Although, that mistakenly worked around iova_bitmap_set() incorrectly setting bits across page boundary. Fix this by reworking the loop inside iova_bitmap_set() to iterate over a range of bits to set (cur_bit .. last_bit) which may span different pinned pages, thus updating @page_idx and @offset as it sets the bits. The previous cap to the first page is now adjusted to be always accounted rather than when there's only a non-zero pgoff. While at it, make @page_idx , @offset and @nbits to be unsigned int given that it won't be more than 512 and 4096 respectively (even a bigger PAGE_SIZE or a smaller struct page size won't make this bigger than the above 32-bit max). Also, delete the stale kdoc on Return type. Cc: Avihai Horon <avihaih@nvidia.com> Fixes:f38044e5ef
("vfio/iova_bitmap: Fix PAGE_SIZE unaligned bitmaps") Co-developed-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Joao Martins <joao.m.martins@oracle.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Tested-by: Avihai Horon <avihaih@nvidia.com> Link: https://lore.kernel.org/r/20221129131235.38880-1-joao.m.martins@oracle.com Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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@ -298,9 +298,7 @@ static unsigned long iova_bitmap_mapped_remaining(struct iova_bitmap *bitmap)
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{
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unsigned long remaining, bytes;
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/* Cap to one page in the first iteration, if PAGE_SIZE unaligned. */
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bytes = !bitmap->mapped.pgoff ? bitmap->mapped.npages << PAGE_SHIFT :
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PAGE_SIZE - bitmap->mapped.pgoff;
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bytes = (bitmap->mapped.npages << PAGE_SHIFT) - bitmap->mapped.pgoff;
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remaining = bitmap->mapped_total_index - bitmap->mapped_base_index;
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remaining = min_t(unsigned long, remaining,
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@ -399,29 +397,27 @@ int iova_bitmap_for_each(struct iova_bitmap *bitmap, void *opaque,
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* Set the bits corresponding to the range [iova .. iova+length-1] in
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* the user bitmap.
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*
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* Return: The number of bits set.
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*/
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void iova_bitmap_set(struct iova_bitmap *bitmap,
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unsigned long iova, size_t length)
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{
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struct iova_bitmap_map *mapped = &bitmap->mapped;
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unsigned long offset = (iova - mapped->iova) >> mapped->pgshift;
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unsigned long nbits = max_t(unsigned long, 1, length >> mapped->pgshift);
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unsigned long page_idx = offset / BITS_PER_PAGE;
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unsigned long page_offset = mapped->pgoff;
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void *kaddr;
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offset = offset % BITS_PER_PAGE;
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unsigned long cur_bit = ((iova - mapped->iova) >>
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mapped->pgshift) + mapped->pgoff * BITS_PER_BYTE;
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unsigned long last_bit = (((iova + length - 1) - mapped->iova) >>
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mapped->pgshift) + mapped->pgoff * BITS_PER_BYTE;
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do {
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unsigned long size = min(BITS_PER_PAGE - offset, nbits);
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unsigned int page_idx = cur_bit / BITS_PER_PAGE;
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unsigned int offset = cur_bit % BITS_PER_PAGE;
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unsigned int nbits = min(BITS_PER_PAGE - offset,
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last_bit - cur_bit + 1);
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void *kaddr;
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kaddr = kmap_local_page(mapped->pages[page_idx]);
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bitmap_set(kaddr + page_offset, offset, size);
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bitmap_set(kaddr, offset, nbits);
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kunmap_local(kaddr);
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page_offset = offset = 0;
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nbits -= size;
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page_idx++;
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} while (nbits > 0);
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cur_bit += nbits;
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} while (cur_bit <= last_bit);
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}
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EXPORT_SYMBOL_GPL(iova_bitmap_set);
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