kernel/linux.git/include/linux/dma-mapping.h, branch v6.19.11

dma-mapping: add missing `inline` for `dma_free_attrs`

2026-04-02T11:25:29+00:00

[ Upstream commit 2cdaff22ed26f1e619aa2b43f27bb84f2c6ef8f8 ] Under an UML build for an upcoming series [1], I got `-Wstatic-in-inline` for `dma_free_attrs`: BINDGEN rust/bindings/bindings_generated.rs - due to target missing In file included from rust/helpers/helpers.c:59: rust/helpers/dma.c:17:2: warning: static function 'dma_free_attrs' is used in an inline function with external linkage [-Wstatic-in-inline] 17 | dma_free_attrs(dev, size, cpu_addr, dma_handle, attrs); | ^ rust/helpers/dma.c:12:1: note: use 'static' to give inline function 'rust_helper_dma_free_attrs' internal linkage 12 | __rust_helper void rust_helper_dma_free_attrs(struct device *dev, size_t size, | ^ | static The issue is that `dma_free_attrs` was not marked `inline` when it was introduced alongside the rest of the stubs. Thus mark it. Fixes: ed6ccf10f24b ("dma-mapping: properly stub out the DMA API for !CONFIG_HAS_DMA") Closes: https://lore.kernel.org/rust-for-linux/20260322194616.89847-1-ojeda@kernel.org/ [1] Signed-off-by: Miguel Ojeda Signed-off-by: Marek Szyprowski Link: https://lore.kernel.org/r/20260325015548.70912-1-ojeda@kernel.org Signed-off-by: Sasha Levin

dma-mapping: Fix DMA_BIT_MASK() macro being broken

2025-12-08T08:40:57+00:00

After commit a50f7456f853 ("dma-mapping: Allow use of DMA_BIT_MASK(64) in global scope"), the DMA_BIT_MASK() macro is broken when passed non trivial statements for the value of 'n'. This is caused by the new version missing parenthesis around 'n' when evaluating 'n'. One example of this breakage is the IPU6 driver now crashing due to it getting DMA-addresses with address bit 32 set even though it has tried to set a 32 bit DMA mask. The IPU6 CSI2 engine has a DMA mask of either 31 or 32 bits depending on if it is in secure mode or not and it sets this masks like this: mmu_info->aperture_end = (dma_addr_t)DMA_BIT_MASK(isp->secure_mode ? IPU6_MMU_ADDR_BITS : IPU6_MMU_ADDR_BITS_NON_SECURE); So the 'n' argument here is "isp->secure_mode ? IPU6_MMU_ADDR_BITS : IPU6_MMU_ADDR_BITS_NON_SECURE" which gets expanded into: isp->secure_mode ? IPU6_MMU_ADDR_BITS : IPU6_MMU_ADDR_BITS_NON_SECURE - 1 With the -1 only being applied in the non secure case, causing the secure mode mask to be one 1 bit too large. Fixes: a50f7456f853 ("dma-mapping: Allow use of DMA_BIT_MASK(64) in global scope") Cc: Sakari Ailus Cc: James Clark Cc: Nathan Chancellor Cc: stable@vger.kernel.org Signed-off-by: Hans de Goede Reviewed-by: Nathan Chancellor Signed-off-by: Marek Szyprowski Link: https://lore.kernel.org/r/20251207184756.97904-1-johannes.goede@oss.qualcomm.com

dma-mapping: Allow use of DMA_BIT_MASK(64) in global scope

2025-11-05T12:43:41+00:00

Clang doesn't like that (1ULL<<(64)) overflows when initializing a global scope variable, even if that part of the ternary isn't used when n = 64. The same initialization can be done without warnings in function scopes, and GCC doesn't mind either way. The build failure that highlighted this was already fixed in a different way [1], which also has detailed links to the Clang issues. However it's not going to be long before the same thing happens again, so it's better to fix the root cause. Fix it by using GENMASK_ULL() which does exactly the same thing, is much more readable anyway, and doesn't have a shift that overflows. [1]: https://lore.kernel.org/all/20250918-mmp-pdma-simplify-dma-addressing-v1-1-5c2be2b85696@riscstar.com/ Signed-off-by: James Clark Reviewed-by: Nathan Chancellor Signed-off-by: Marek Szyprowski Link: https://lore.kernel.org/r/20251030-james-fix-dma_bit_mask-v1-1-ad1ce7cfab6e@linaro.org

dma-mapping: export new dma_*map_phys() interface

2025-09-11T22:18:21+00:00

Introduce new DMA mapping functions dma_map_phys() and dma_unmap_phys() that operate directly on physical addresses instead of page+offset parameters. This provides a more efficient interface for drivers that already have physical addresses available. The new functions are implemented as the primary mapping layer, with the existing dma_map_page_attrs()/dma_map_resource() and dma_unmap_page_attrs()/dma_unmap_resource() functions converted to simple wrappers around the phys-based implementations. In case dma_map_page_attrs(), the struct page is converted to physical address with help of page_to_phys() function and dma_map_resource() provides physical address as is together with addition of DMA_ATTR_MMIO attribute. The old page-based API is preserved in mapping.c to ensure that existing code won't be affected by changing EXPORT_SYMBOL to EXPORT_SYMBOL_GPL variant for dma_*map_phys(). Reviewed-by: Jason Gunthorpe Reviewed-by: Keith Busch Signed-off-by: Leon Romanovsky Signed-off-by: Marek Szyprowski Link: https://lore.kernel.org/r/54cc52af91777906bbe4a386113437ba0bcfba9c.1757423202.git.leonro@nvidia.com

dma-mapping: introduce new DMA attribute to indicate MMIO memory

2025-09-11T22:08:07+00:00

This patch introduces the DMA_ATTR_MMIO attribute to mark DMA buffers that reside in memory-mapped I/O (MMIO) regions, such as device BARs exposed through the host bridge, which are accessible for peer-to-peer (P2P) DMA. This attribute is especially useful for exporting device memory to other devices for DMA without CPU involvement, and avoids unnecessary or potentially detrimental CPU cache maintenance calls. DMA_ATTR_MMIO is supposed to provide dma_map_resource() functionality without need to call to special function and perform branching when processing generic containers like bio_vec by the callers. Reviewed-by: Jason Gunthorpe Signed-off-by: Leon Romanovsky Signed-off-by: Marek Szyprowski Link: https://lore.kernel.org/r/6f058ec395c5348014860dbc2eed348c17975843.1757423202.git.leonro@nvidia.com

Merge tag 'dma-mapping-6.16-2025-05-26' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux

2025-05-28T03:09:06+00:00

Pull dma-mapping updates from Marek Szyprowski: "New two step DMA mapping API, which is is a first step to a long path to provide alternatives to scatterlist and to remove hacks, abuses and design mistakes related to scatterlists. This new approach optimizes some calls to DMA-IOMMU layer and cache maintenance by batching them, reduces memory usage as it is no need to store mapped DMA addresses to unmap them, and reduces some function call overhead. It is a combination effort of many people, lead and developed by Christoph Hellwig and Leon Romanovsky" * tag 'dma-mapping-6.16-2025-05-26' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux: docs: core-api: document the IOVA-based API dma-mapping: add a dma_need_unmap helper dma-mapping: Implement link/unlink ranges API iommu/dma: Factor out a iommu_dma_map_swiotlb helper dma-mapping: Provide an interface to allow allocate IOVA iommu: add kernel-doc for iommu_unmap_fast iommu: generalize the batched sync after map interface dma-mapping: move the PCI P2PDMA mapping helpers to pci-p2pdma.h PCI/P2PDMA: Refactor the p2pdma mapping helpers

dma-mapping: add a dma_need_unmap helper

2025-05-06T06:36:53+00:00

Add helper that allows a driver to skip calling dma_unmap_* if the DMA layer can guarantee that they are no-nops. Signed-off-by: Christoph Hellwig Tested-by: Jens Axboe Reviewed-by: Luis Chamberlain Signed-off-by: Leon Romanovsky Signed-off-by: Marek Szyprowski

dma-mapping: Implement link/unlink ranges API

2025-05-06T06:36:53+00:00

Introduce new DMA APIs to perform DMA linkage of buffers in layers higher than DMA. In proposed API, the callers will perform the following steps. In map path: if (dma_can_use_iova(...)) dma_iova_alloc() for (page in range) dma_iova_link_next(...) dma_iova_sync(...) else /* Fallback to legacy map pages */ for (all pages) dma_map_page(...) In unmap path: if (dma_can_use_iova(...)) dma_iova_destroy() else for (all pages) dma_unmap_page(...) Reviewed-by: Christoph Hellwig Tested-by: Jens Axboe Reviewed-by: Luis Chamberlain Signed-off-by: Leon Romanovsky Signed-off-by: Marek Szyprowski

dma-mapping: Provide an interface to allow allocate IOVA

2025-05-06T06:36:53+00:00

The existing .map_pages() callback provides both allocating of IOVA and linking DMA pages. That combination works great for most of the callers who use it in control paths, but is less effective in fast paths where there may be multiple calls to map_page(). These advanced callers already manage their data in some sort of database and can perform IOVA allocation in advance, leaving range linkage operation to be in fast path. Provide an interface to allocate/deallocate IOVA and next patch link/unlink DMA ranges to that specific IOVA. In the new API a DMA mapping transaction is identified by a struct dma_iova_state, which holds some recomputed information for the transaction which does not change for each page being mapped, so add a check if IOVA can be used for the specific transaction. The API is exported from dma-iommu as it is the only implementation supported, the namespace is clearly different from iommu_* functions which are not allowed to be used. This code layout allows us to save function call per API call used in datapath as well as a lot of boilerplate code. Reviewed-by: Christoph Hellwig Tested-by: Jens Axboe Reviewed-by: Luis Chamberlain Signed-off-by: Leon Romanovsky Signed-off-by: Marek Szyprowski

dma-mapping: avoid potential unused data compilation warning

2025-04-17T05:44:35+00:00

When CONFIG_NEED_DMA_MAP_STATE is not defined, dma-mapping clients might report unused data compilation warnings for dma_unmap_*() calls arguments. Redefine macros for those calls to let compiler to notice that it is okay when the provided arguments are not used. Reported-by: Andy Shevchenko Suggested-by: Jakub Kicinski Signed-off-by: Marek Szyprowski Tested-by: Andy Shevchenko Link: https://lore.kernel.org/r/20250415075659.428549-1-m.szyprowski@samsung.com