From cbf53074a528191df82b4dba1e3d21191102255e Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 8 Mar 2024 15:28:26 +0000 Subject: swiotlb: Honour dma_alloc_coherent() alignment in swiotlb_alloc() core-api/dma-api-howto.rst states the following properties of dma_alloc_coherent(): | The CPU virtual address and the DMA address are both guaranteed to | be aligned to the smallest PAGE_SIZE order which is greater than or | equal to the requested size. However, swiotlb_alloc() passes zero for the 'alloc_align_mask' parameter of swiotlb_find_slots() and so this property is not upheld. Instead, allocations larger than a page are aligned to PAGE_SIZE, Calculate the mask corresponding to the page order suitable for holding the allocation and pass that to swiotlb_find_slots(). Fixes: e81e99bacc9f ("swiotlb: Support aligned swiotlb buffers") Signed-off-by: Will Deacon Reviewed-by: Michael Kelley Reviewed-by: Petr Tesarik Tested-by: Nicolin Chen Tested-by: Michael Kelley Signed-off-by: Christoph Hellwig --- kernel/dma/swiotlb.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel/dma') diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 88114433f1e6..a3645a9ae68e 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -1679,12 +1679,14 @@ struct page *swiotlb_alloc(struct device *dev, size_t size) struct io_tlb_mem *mem = dev->dma_io_tlb_mem; struct io_tlb_pool *pool; phys_addr_t tlb_addr; + unsigned int align; int index; if (!mem) return NULL; - index = swiotlb_find_slots(dev, 0, size, 0, &pool); + align = (1 << (get_order(size) + PAGE_SHIFT)) - 1; + index = swiotlb_find_slots(dev, 0, size, align, &pool); if (index == -1) return NULL; -- cgit v1.2.3