[PATCH v2 0/3] Fix double allocation in swiotlb_alloc()

[Will Deacon <will@kernel.org>]

Hi all,

This is version two of the patches I posted last week:

https://lore.kernel.org/r/20240126151956.10014-1-will@kernel.org

Many thanks to Petr and Christoph for the discussion on that.

Changes since v1 include:

  - Fix swiotlb_alloc() to honour the alignment requirements of
    dma_alloc_coherent(). This is a new patch, and I think it's been
    broken forever (practically stopping at page alignment). I've left
    swiotlb_map() alone, so that doesn't necessarily return page-aligned
    DMA addresses, but I think that's ok.

  - Avoid updating 'alloc_align_mask' and instead just compute the
    'stride' directly to avoid a superfluous alignment requirement
    for mapping requests greater than a page.

  - Use get_max_slots() instead of open-coding the same logic.

  - Remove the extra 'goto' in swiotlb_search_pool_area() and collapse
    the conditionals instead.

  - Reword warning message when swiotlb_alloc() receives non page-aligned
    allocation.

  - Annotate non page-aligned case with unlikely().

Cheers,

Will

Cc: iommu@lists.linux.dev
Cc: Christoph Hellwig <hch@lst.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Petr Tesarik <petr.tesarik1@huawei-partners.com>
Cc: Dexuan Cui <decui@microsoft.com>

--->8

Will Deacon (3):
  swiotlb: Fix allocation alignment requirement when searching slots
  swiotlb: Enforce page alignment in swiotlb_alloc()
  swiotlb: Honour dma_alloc_coherent() alignment in swiotlb_alloc()

 kernel/dma/swiotlb.c | 39 ++++++++++++++++++++++++---------------
 1 file changed, 24 insertions(+), 15 deletions(-)

-- 
2.43.0.429.g432eaa2c6b-goog