diff options
| author | Will Deacon <will@kernel.org> | 2024-03-08 16:28:29 +0100 |
|---|---|---|
| committer | Christoph Hellwig <hch@lst.de> | 2024-03-13 19:39:34 +0100 |
| commit | 14cebf689a78e8a1c041138af221ef6eac6bc7da (patch) | |
| tree | a556053871a62a03b875d023c52449470416b361 | |
| parent | iommu/dma: Force swiotlb_max_mapping_size on an untrusted device (diff) | |
| download | linux-14cebf689a78e8a1c041138af221ef6eac6bc7da.tar.xz linux-14cebf689a78e8a1c041138af221ef6eac6bc7da.zip | |
swiotlb: Reinstate page-alignment for mappings >= PAGE_SIZE
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.
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>
| -rw-r--r-- | kernel/dma/swiotlb.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index f212943e51ca..86fe172b5958 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -1015,6 +1015,17 @@ static int swiotlb_search_pool_area(struct device *dev, struct io_tlb_pool *pool 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 * offsetting into the allocation. @@ -1028,13 +1039,6 @@ static int swiotlb_search_pool_area(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; |