From 3db240de7e4078d597661574a0dc523064adca67 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 8 Mar 2024 15:28:26 +0000 Subject: [PATCH] swiotlb: Honour dma_alloc_coherent() alignment in swiotlb_alloc() BugLink: https://bugs.launchpad.net/bugs/2060531 [ Upstream commit cbf53074a528191df82b4dba1e3d21191102255e ] 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 Signed-off-by: Sasha Levin Signed-off-by: Paolo Pisati --- kernel/dma/swiotlb.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 2ec2cc81f1a2..a619e22fecbf 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -1633,12 +1633,14 @@ 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;