linux-toradex.git/kernel/dma/mapping.c, branch v7.0-rc6 Linux kernel for Apalis and Colibri modules dma-mapping: Introduce DMA require coherency attribute 2026-03-20T11:05:36+00:00 Leon Romanovsky leonro@nvidia.com 2026-03-16T19:06:48+00:00 e6a58fa2556203a7f6731b4071705dc81cca5ca5 The mapping buffers which carry this attribute require DMA coherent system. This means that they can't take SWIOTLB path, can perform CPU cache overlap and doesn't perform cache flushing. Signed-off-by: Leon Romanovsky <leonro@nvidia.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Link: https://lore.kernel.org/r/20260316-dma-debug-overlap-v3-4-1dde90a7f08b@nvidia.com 
The mapping buffers which carry this attribute require DMA coherent system.
This means that they can't take SWIOTLB path, can perform CPU cache overlap
and doesn't perform cache flushing.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260316-dma-debug-overlap-v3-4-1dde90a7f08b@nvidia.com
treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21T09:02:28+00:00 Kees Cook kees@kernel.org 2026-02-21T07:49:23+00:00 69050f8d6d075dc01af7a5f2f550a8067510366f This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook <kees@kernel.org> 
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook <kees@kernel.org>
powerpc/iommu: bypass DMA APIs for coherent allocations for pre-mapped memory 2026-01-07T04:03:55+00:00 Gaurav Batra gbatra@linux.ibm.com 2025-11-07T16:11:05+00:00 1471c517cf7dae1a6342fb821d8ed501af956dd0 Leverage ARCH_HAS_DMA_MAP_DIRECT config option for coherent allocations as well. This will bypass DMA ops for memory allocations that have been pre-mapped. Always set device bus_dma_limit when memory is pre-mapped. In some architectures, like PowerPC, pmemory can be converted to regular memory via daxctl command. This will gate the coherent allocations to pre-mapped RAM only, by dma_coherent_ok(). Signed-off-by: Gaurav Batra <gbatra@linux.ibm.com> Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com> Link: https://patch.msgid.link/20251107161105.85999-1-gbatra@linux.ibm.com 
Leverage ARCH_HAS_DMA_MAP_DIRECT config option for coherent allocations as
well. This will bypass DMA ops for memory allocations that have been
pre-mapped.

Always set device bus_dma_limit when memory is pre-mapped. In some
architectures, like PowerPC, pmemory can be converted to regular memory via
daxctl command. This will gate the coherent allocations to pre-mapped RAM
only, by dma_coherent_ok().

Signed-off-by: Gaurav Batra <gbatra@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20251107161105.85999-1-gbatra@linux.ibm.com
dma-mapping: remove unused map_page callback 2025-10-29T09:27:31+00:00 Leon Romanovsky leonro@nvidia.com 2025-10-15T09:13:00+00:00 131971f67e258170c678fe572fda95f8cef88e66 After conversion of arch code to use physical address mapping, there are no users of .map_page() and .unmap_page() callbacks, so let's remove them. Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Leon Romanovsky <leonro@nvidia.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Link: https://lore.kernel.org/r/20251015-remove-map-page-v5-14-3bbfe3a25cdf@kernel.org 
After conversion of arch code to use physical address mapping,
there are no users of .map_page() and .unmap_page() callbacks,
so let's remove them.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20251015-remove-map-page-v5-14-3bbfe3a25cdf@kernel.org
dma-mapping: remove unused mapping resource callbacks 2025-10-29T09:27:30+00:00 Leon Romanovsky leonro@nvidia.com 2025-10-15T09:12:52+00:00 14cb413af00c5d3950d1a339dd2b6f01ce313fce After ARM and XEN conversions to use physical addresses for the mapping, there are no in-kernel users for map_resource/unmap_resource callbacks, so remove them. Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Leon Romanovsky <leonro@nvidia.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Link: https://lore.kernel.org/r/20251015-remove-map-page-v5-6-3bbfe3a25cdf@kernel.org 
After ARM and XEN conversions to use physical addresses for the mapping,
there are no in-kernel users for map_resource/unmap_resource callbacks,
so remove them.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20251015-remove-map-page-v5-6-3bbfe3a25cdf@kernel.org
dma-mapping: prepare dma_map_ops to conversion to physical address 2025-10-29T09:27:29+00:00 Leon Romanovsky leonro@nvidia.com 2025-10-15T09:12:47+00:00 ed7fc3cbb38ffdca7a189e15982ce96acab4684c Add new .map_phys() and .unmap_phys() callbacks to dma_map_ops as a preparation to replace .map_page() and .unmap_page() respectively. Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Leon Romanovsky <leonro@nvidia.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Link: https://lore.kernel.org/r/20251015-remove-map-page-v5-1-3bbfe3a25cdf@kernel.org 
Add new .map_phys() and .unmap_phys() callbacks to dma_map_ops as a
preparation to replace .map_page() and .unmap_page() respectively.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20251015-remove-map-page-v5-1-3bbfe3a25cdf@kernel.org
dma-mapping: export new dma_*map_phys() interface 2025-09-11T22:18:21+00:00 Leon Romanovsky leonro@nvidia.com 2025-09-09T13:27:39+00:00 f7326196a781622b33bfbdabb00f5e72b5fb5679 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 <jgg@nvidia.com> Reviewed-by: Keith Busch <kbusch@kernel.org> Signed-off-by: Leon Romanovsky <leonro@nvidia.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Link: https://lore.kernel.org/r/54cc52af91777906bbe4a386113437ba0bcfba9c.1757423202.git.leonro@nvidia.com 
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 <jgg@nvidia.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/54cc52af91777906bbe4a386113437ba0bcfba9c.1757423202.git.leonro@nvidia.com
dma-mapping: implement DMA_ATTR_MMIO for dma_(un)map_page_attrs() 2025-09-11T22:18:20+00:00 Leon Romanovsky leonro@nvidia.com 2025-09-09T13:27:37+00:00 18c9cbb042c930eb37f68df216319a371f4fcb22 Make dma_map_page_attrs() and dma_map_page_attrs() respect DMA_ATTR_MMIO. DMA_ATR_MMIO makes the functions behave the same as dma_(un)map_resource(): - No swiotlb is possible - Legacy dma_ops arches use ops->map_resource() - No kmsan - No arch_dma_map_phys_direct() The prior patches have made the internal functions called here support DMA_ATTR_MMIO. This is also preparation for turning dma_map_resource() into an inline calling dma_map_phys(DMA_ATTR_MMIO) to consolidate the flows. Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Leon Romanovsky <leonro@nvidia.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Link: https://lore.kernel.org/r/3660e2c78ea409d6c483a215858fb3af52cd0ed3.1757423202.git.leonro@nvidia.com 
Make dma_map_page_attrs() and dma_map_page_attrs() respect
DMA_ATTR_MMIO.

DMA_ATR_MMIO makes the functions behave the same as
dma_(un)map_resource():
 - No swiotlb is possible
 - Legacy dma_ops arches use ops->map_resource()
 - No kmsan
 - No arch_dma_map_phys_direct()

The prior patches have made the internal functions called here
support DMA_ATTR_MMIO.

This is also preparation for turning dma_map_resource() into an inline
calling dma_map_phys(DMA_ATTR_MMIO) to consolidate the flows.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/3660e2c78ea409d6c483a215858fb3af52cd0ed3.1757423202.git.leonro@nvidia.com
kmsan: convert kmsan_handle_dma to use physical addresses 2025-09-11T22:18:20+00:00 Leon Romanovsky leonro@nvidia.com 2025-09-09T13:27:36+00:00 6eb1e769b2c13a33cb2ca694454a7561d3d72c0a Convert the KMSAN DMA handling function from page-based to physical address-based interface. The refactoring renames kmsan_handle_dma() parameters from accepting (struct page *page, size_t offset, size_t size) to (phys_addr_t phys, size_t size). The existing semantics where callers are expected to provide only kmap memory is continued here. Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Leon Romanovsky <leonro@nvidia.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Link: https://lore.kernel.org/r/3557cbaf66e935bc794f37d2b891ef75cbf2c80c.1757423202.git.leonro@nvidia.com 
Convert the KMSAN DMA handling function from page-based to physical
address-based interface.

The refactoring renames kmsan_handle_dma() parameters from accepting
(struct page *page, size_t offset, size_t size) to (phys_addr_t phys,
size_t size). The existing semantics where callers are expected to
provide only kmap memory is continued here.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/3557cbaf66e935bc794f37d2b891ef75cbf2c80c.1757423202.git.leonro@nvidia.com
dma-mapping: convert dma_direct_*map_page to be phys_addr_t based 2025-09-11T22:18:20+00:00 Leon Romanovsky leonro@nvidia.com 2025-09-09T13:27:35+00:00 e53d29f957b36ba1666331956c6ccb047bb157d2 Convert the DMA direct mapping functions to accept physical addresses directly instead of page+offset parameters. The functions were already operating on physical addresses internally, so this change eliminates the redundant page-to-physical conversion at the API boundary. The functions dma_direct_map_page() and dma_direct_unmap_page() are renamed to dma_direct_map_phys() and dma_direct_unmap_phys() respectively, with their calling convention changed from (struct page *page, unsigned long offset) to (phys_addr_t phys). Architecture-specific functions arch_dma_map_page_direct() and arch_dma_unmap_page_direct() are similarly renamed to arch_dma_map_phys_direct() and arch_dma_unmap_phys_direct(). The is_pci_p2pdma_page() checks are replaced with DMA_ATTR_MMIO checks to allow integration with dma_direct_map_resource and dma_direct_map_phys() is extended to support MMIO path either. Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Leon Romanovsky <leonro@nvidia.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Link: https://lore.kernel.org/r/bb15a22f76dc2e26683333ff54e789606cfbfcf0.1757423202.git.leonro@nvidia.com 
Convert the DMA direct mapping functions to accept physical addresses
directly instead of page+offset parameters. The functions were already
operating on physical addresses internally, so this change eliminates
the redundant page-to-physical conversion at the API boundary.

The functions dma_direct_map_page() and dma_direct_unmap_page() are
renamed to dma_direct_map_phys() and dma_direct_unmap_phys() respectively,
with their calling convention changed from (struct page *page,
unsigned long offset) to (phys_addr_t phys).

Architecture-specific functions arch_dma_map_page_direct() and
arch_dma_unmap_page_direct() are similarly renamed to
arch_dma_map_phys_direct() and arch_dma_unmap_phys_direct().

The is_pci_p2pdma_page() checks are replaced with DMA_ATTR_MMIO checks
to allow integration with dma_direct_map_resource and dma_direct_map_phys()
is extended to support MMIO path either.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/bb15a22f76dc2e26683333ff54e789606cfbfcf0.1757423202.git.leonro@nvidia.com