This is a note to let you know that I've just added the patch titled
swiotlb: Honour dma_alloc_coherent() alignment in swiotlb_alloc()
to the 6.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
swiotlb-honour-dma_alloc_coherent-alignment-in-swiot.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit e324af0ec31e3adecc6068845f81dadb883d7b11
Author: Will Deacon <will@xxxxxxxxxx>
Date: Fri Mar 8 15:28:26 2024 +0000
swiotlb: Honour dma_alloc_coherent() alignment in swiotlb_alloc()
[ 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 <will@xxxxxxxxxx>
Reviewed-by: Michael Kelley <mhklinux@xxxxxxxxxxx>
Reviewed-by: Petr Tesarik <petr.tesarik1@xxxxxxxxxxxxxxxxxxx>
Tested-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
Tested-by: Michael Kelley <mhklinux@xxxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 2ec2cc81f1a27..a619e22fecbf7 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;
