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swiotlb: Reinstate page-alignment for mappings >= PAGE_SIZE

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commit 14cebf689a78e8a1c041138af221ef6eac6bc7da upstream.

For swiotlb allocations >= PAGE_SIZE, the slab search historically
adjusted the stride to avoid checking unaligned slots. This had the
side-effect of aligning large mapping requests to PAGE_SIZE, but that
was broken by 0eee5ae10256 ("swiotlb: fix slot alignment checks").

Since this alignment could be relied upon drivers, reinstate PAGE_SIZE
alignment for swiotlb mappings >= PAGE_SIZE.

Cc: stable@vger.kernel.org # v6.6+
Reported-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Petr Tesarik <petr.tesarik1@huawei-partners.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Will Deacon 2024-06-17 11:23:14 -03:00 committed by Greg Kroah-Hartman
parent 6033fc9522
commit 6c385c1fa0
1 changed files with 11 additions and 7 deletions
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18
kernel/dma/swiotlb.c
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@ -992,6 +992,17 @@ static int swiotlb_area_find_slots(struct device *dev, struct io_tlb_pool *pool,
BUG_ON(!nslots);
BUG_ON(area_index >= pool->nareas);
/*
* Historically, swiotlb allocations >= PAGE_SIZE were guaranteed to be
* page-aligned in the absence of any other alignment requirements.
* 'alloc_align_mask' was later introduced to specify the alignment
* explicitly, however this is passed as zero for streaming mappings
* and so we preserve the old behaviour there in case any drivers are
* relying on it.
*/
if (!alloc_align_mask && !iotlb_align_mask && alloc_size >= PAGE_SIZE)
alloc_align_mask = PAGE_SIZE - 1;
/*
* Ensure that the allocation is at least slot-aligned and update
* 'iotlb_align_mask' to ignore bits that will be preserved when
@ -1006,13 +1017,6 @@ static int swiotlb_area_find_slots(struct device *dev, struct io_tlb_pool *pool,
*/
stride = get_max_slots(max(alloc_align_mask, iotlb_align_mask));
/*
* For allocations of PAGE_SIZE or larger only look for page aligned
* allocations.
*/
if (alloc_size >= PAGE_SIZE)
stride = umax(stride, PAGE_SHIFT - IO_TLB_SHIFT + 1);
spin_lock_irqsave(&area->lock, flags);
if (unlikely(nslots > pool->area_nslabs - area->used))
goto not_found;