Re: [PATCH v8 12/23] dma: swiotlb: pass mapping attributes by reference
From: Mostafa Saleh <smostafa@google.com>
Date: 2026-07-28 14:41:49
Also in:
linux-arm-kernel, linux-coco, linux-iommu, linux-s390, lkml
On Fri, Jul 17, 2026 at 11:34:30PM +0530, Aneesh Kumar K.V (Arm) wrote:
Change swiotlb_tbl_map_single() to take the DMA mapping attributes by reference and update the direct callers accordingly. This is a preparatory change for a follow-up patch which updates the attributes based on the selected swiotlb pool. Keeping the signature change separate makes the follow-up patch easier to review.
I do not understand the point of this, why would swiotlb_tbl_map_single() force attrs over the caller which should already know the context (whether DMA is shared or not) which case would this be useful to force from the SWIOTLB code? Thanks, Mostafa
quoted hunk ↗ jump to hunk
No functional change in this patch. Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Tested-by: Michael Kelley <redacted> Tested-by: Mostafa Saleh <smostafa@google.com> Reviewed-by: Petr Tesarik <redacted> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org> --- drivers/iommu/dma-iommu.c | 2 +- drivers/xen/swiotlb-xen.c | 2 +- include/linux/swiotlb.h | 2 +- kernel/dma/swiotlb.c | 6 +++--- 4 files changed, 6 insertions(+), 6 deletions(-)diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index 83bf15ae9777..c42e40e60575 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c@@ -1180,7 +1180,7 @@ static phys_addr_t iommu_dma_map_swiotlb(struct device *dev, phys_addr_t phys, trace_swiotlb_bounced(dev, phys, size); phys = swiotlb_tbl_map_single(dev, phys, size, iova_mask(iovad), dir, - attrs); + &attrs); /* * Untrusted devices should not see padding areas with random leftoverdiff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c index 2cbf2b588f5b..8c4abe65cd49 100644 --- a/drivers/xen/swiotlb-xen.c +++ b/drivers/xen/swiotlb-xen.c@@ -243,7 +243,7 @@ static dma_addr_t xen_swiotlb_map_phys(struct device *dev, phys_addr_t phys, */ trace_swiotlb_bounced(dev, dev_addr, size); - map = swiotlb_tbl_map_single(dev, phys, size, 0, dir, attrs); + map = swiotlb_tbl_map_single(dev, phys, size, 0, dir, &attrs); if (map == (phys_addr_t)DMA_MAPPING_ERROR) return DMA_MAPPING_ERROR;diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index c92ff6791595..ea4c0a292dea 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h@@ -238,7 +238,7 @@ static inline phys_addr_t default_swiotlb_limit(void) phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t phys, size_t mapping_size, unsigned int alloc_aligned_mask, - enum dma_data_direction dir, unsigned long attrs); + enum dma_data_direction dir, unsigned long *attrs); dma_addr_t swiotlb_map(struct device *dev, phys_addr_t phys, size_t size, enum dma_data_direction dir, unsigned long attrs);diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 908de28aceb2..046ae92c4832 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c@@ -1396,7 +1396,7 @@ static unsigned long mem_used(struct io_tlb_mem *mem) */ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr, size_t mapping_size, unsigned int alloc_align_mask, - enum dma_data_direction dir, unsigned long attrs) + enum dma_data_direction dir, unsigned long *attrs) { struct io_tlb_mem *mem = dev->dma_io_tlb_mem; unsigned int offset;@@ -1430,7 +1430,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr, size = ALIGN(mapping_size + offset, alloc_align_mask + 1); index = swiotlb_find_slots(dev, orig_addr, size, alloc_align_mask, &pool); if (index == -1) { - if (!(attrs & DMA_ATTR_NO_WARN)) + if (!(*attrs & DMA_ATTR_NO_WARN)) dev_warn_ratelimited(dev, "swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n", size, mem->nslabs, mem_used(mem));@@ -1609,7 +1609,7 @@ dma_addr_t swiotlb_map(struct device *dev, phys_addr_t paddr, size_t size, trace_swiotlb_bounced(dev, phys_to_dma(dev, paddr), size); - swiotlb_addr = swiotlb_tbl_map_single(dev, paddr, size, 0, dir, attrs); + swiotlb_addr = swiotlb_tbl_map_single(dev, paddr, size, 0, dir, &attrs); if (swiotlb_addr == (phys_addr_t)DMA_MAPPING_ERROR) return DMA_MAPPING_ERROR;-- 2.43.0