kernel/linux.git/drivers/dma-buf/Makefile, branch v7.2-rc1

dma-buf: Remove the old selftest

2026-04-16T10:34:00+00:00

Nothing uses this framework anymore, remove it. Signed-off-by: Jason Gunthorpe Reviewed-by: Christian König Signed-off-by: Christian König Link: https://lore.kernel.org/r/5-v1-0a349a394eff+14110-dmabuf_kunit_jgg@nvidia.com

dma-buf: Change st-dma-fence-chain.c to use kunit

2026-04-16T10:34:00+00:00

Modernize the open coded test framework by using kunit. Signed-off-by: Jason Gunthorpe Reviewed-by: Christian König Signed-off-by: Christian König Link: https://lore.kernel.org/r/4-v1-0a349a394eff+14110-dmabuf_kunit_jgg@nvidia.com

dma-buf: Change st-dma-fence-unwrap.c to use kunit

2026-04-16T10:34:00+00:00

Modernize the open coded test framework by using kunit. Signed-off-by: Jason Gunthorpe Reviewed-by: Christian König Signed-off-by: Christian König Link: https://lore.kernel.org/r/3-v1-0a349a394eff+14110-dmabuf_kunit_jgg@nvidia.com

dma-buf: Change st-dma-fence.c to use kunit

2026-04-16T10:34:00+00:00

Modernize the open coded test framework by using kunit. Add a num_online_cpus() check to test_race_signal_callback() as the default kunit.py runs the VM with a single CPU and this test depends on two truly parallel kthreads. Skip it instead of hanging. Signed-off-by: Jason Gunthorpe Reviewed-by: Christian König Signed-off-by: Christian König Link: https://lore.kernel.org/r/2-v1-0a349a394eff+14110-dmabuf_kunit_jgg@nvidia.com

dma-buf: Change st-dma-resv.c to use kunit

2026-04-16T10:34:00+00:00

Modernize the open coded test framework by using kunit. The kunit tool can be used to build a kernel and run it in a VM with: $ tools/testing/kunit/kunit.py run --build_dir build_kunit_x86_64 --arch x86_64 --kunitconfig ./drivers/dma-buf/.kunitconfig Along with the other ways to run kunits. To make the kunit tool work like this the DMABUF_KUNIT_TEST kconfig must select DMA_SHARED_BUFFER to get it turned on without building a driver using it. Signed-off-by: Jason Gunthorpe Reviewed-by: Christian König Signed-off-by: Christian König Link: https://lore.kernel.org/r/1-v1-0a349a394eff+14110-dmabuf_kunit_jgg@nvidia.com

dma-buf: Remove DMA-BUF sysfs stats

2026-01-19T13:40:01+00:00

Commit bdb8d06dfefd ("dmabuf: Add the capability to expose DMA-BUF stats in sysfs") added dmabuf statistics to sysfs in 2021 under CONFIG_DMABUF_SYSFS_STATS. After being used in production, performance problems were discovered leading to its deprecation in 2022 in commit e0a9f1fe206a ("dma-buf: deprecate DMABUF_SYSFS_STATS"). Some of the problems with this interface were discussed in my LPC 2025 talk. [1][2] Android was probably the last user of the interface, which has since been migrated to use the dmabuf BPF iterator [3] to obtain the same information more cheaply. As promised in that series, now that the longterm stable 6.18 kernel has been released let's remove the sysfs dmabuf statistics from the kernel. [1] https://www.youtube.com/watch?v=D83qygudq9c [2] https://lpc.events/event/19/contributions/2118/ [3] https://lore.kernel.org/all/20250522230429.941193-1-tjmercier@google.com/ Signed-off-by: T.J. Mercier Reviewed-by: Christian König Signed-off-by: Sumit Semwal Link: https://patch.msgid.link/20260116190517.3268458-1-tjmercier@google.com

dma-buf: provide phys_vec to scatter-gather mapping routine

2025-11-20T19:02:19+00:00

Add dma_buf_phys_vec_to_sgt() and dma_buf_free_sgt() helpers to convert an array of MMIO physical address ranges into scatter-gather tables with proper DMA mapping. These common functions are a starting point and support any PCI drivers creating mappings from their BAR's MMIO addresses. VFIO is one case, as shortly will be RDMA. We can review existing DRM drivers to refactor them separately. We hope this will evolve into routines to help common DRM that include mixed CPU and MMIO mappings. Compared to the dma_map_resource() abuse this implementation handles the complicated PCI P2P scenarios properly, especially when an IOMMU is enabled: - Direct bus address mapping without IOVA allocation for PCI_P2PDMA_MAP_BUS_ADDR, using pci_p2pdma_bus_addr_map(). This happens if the IOMMU is enabled but the PCIe switch ACS flags allow transactions to avoid the host bridge. Further, this handles the slightly obscure, case of MMIO with a phys_addr_t that is different from the physical BAR programming (bus offset). The phys_addr_t is converted to a dma_addr_t and accommodates this effect. This enables certain real systems to work, especially on ARM platforms. - Mapping through host bridge with IOVA allocation and DMA_ATTR_MMIO attribute for MMIO memory regions (PCI_P2PDMA_MAP_THRU_HOST_BRIDGE). This happens when the IOMMU is enabled and the ACS flags are forcing all traffic to the IOMMU - ie for virtualization systems. - Cases where P2P is not supported through the host bridge/CPU. The P2P subsystem is the proper place to detect this and block it. Helper functions fill_sg_entry() and calc_sg_nents() handle the scatter-gather table construction, splitting large regions into UINT_MAX-sized chunks to fit within sg->length field limits. Since the physical address based DMA API forbids use of the CPU list of the scatterlist this will produce a mangled scatterlist that has a fully zero-length and NULL'd CPU list. The list is 0 length, all the struct page pointers are NULL and zero sized. This is stronger and more robust than the existing mangle_sg_table() technique. It is a future project to migrate DMABUF as a subsystem away from using scatterlist for this data structure. Reviewed-by: Kevin Tian Reviewed-by: Nicolin Chen Reviewed-by: Jason Gunthorpe Tested-by: Alex Mastro Tested-by: Nicolin Chen Signed-off-by: Leon Romanovsky Acked-by: Christian König Acked-by: Ankit Agrawal Link: https://lore.kernel.org/r/20251120-dmabuf-vfio-v9-6-d7f71607f371@nvidia.com Signed-off-by: Alex Williamson

dma-buf: cleanup dma_fence_unwrap implementation

2022-05-30T12:16:32+00:00

Move the code from the inline functions into exported functions. Signed-off-by: Christian König Acked-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220518135844.3338-3-christian.koenig@amd.com

dma-buf: add dma_fence_unwrap v2

2022-03-25T13:18:28+00:00

Add a general purpose helper to deep dive into dma_fence_chain/dma_fence_array structures and iterate over all the fences in them. This is useful when we need to flatten out all fences in those structures. v2: some selftests cleanup, improved function naming and documentation Signed-off-by: Christian König Reviewed-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220311110244.1245-1-christian.koenig@amd.com

dma-buf: add dma_resv selftest v4

2021-10-22T12:19:51+00:00

Just exercising a very minor subset of the functionality, but already proven useful. v2: add missing locking v3: some more cleanup and consolidation, add unlocked test as well v4: add a dma_resv_get_fences selftest Signed-off-by: Christian König Reviewed-by: Tvrtko Ursulin (v3) Reviewed-by: Daniel Vetter (v3) Link: https://patchwork.freedesktop.org/patch/msgid/20211005113742.1101-4-christian.koenig@amd.com