linux.git/include/linux/dma-buf.h, branch v7.1-rc2

Merge drm/drm-fixes into drm-misc-fixes

2026-04-27T08:26:49+00:00

Getting fixes and updates from v7.1-rc1.

Signed-off-by: Thomas Zimmermann

dma-buf: fix stale @lock references in struct dma_buf documentation

2026-04-23T08:01:46+00:00

The kernel-doc comments for vmapping_counter and vmap_ptr in struct
dma_buf reference "@lock" as the protecting lock, but struct dma_buf
no longer has a "lock" member. The mutex was removed in favor of using
the dma_resv lock exclusively. The implementation correctly uses
dma_resv_assert_held(dmabuf->resv) in dma_buf_vmap() and
dma_buf_vunmap(), so update the documentation to reference @resv
instead.

Signed-off-by: gaoxiang17 
Reviewed-by: Christian König 
Signed-off-by: Christian König 
Link: https://lore.kernel.org/r/20260415054101.535520-1-gxxa03070307@gmail.com

dma-buf: Add dma_buf_attach_revocable()

2026-02-23T18:51:40+00:00

Some exporters need a flow to synchronously revoke access to the DMA-buf
by importers. Once revoke is completed the importer is not permitted to
touch the memory otherwise they may get IOMMU faults, AERs, or worse.

DMA-buf today defines a revoke flow, for both pinned and dynamic
importers, which is broadly:

	dma_resv_lock(dmabuf->resv, NULL);
	// Prevent new mappings from being established
	priv->revoked = true;

	// Tell all importers to eventually unmap
	dma_buf_invalidate_mappings(dmabuf);

	// Wait for any inprogress fences on the old mapping
	dma_resv_wait_timeout(dmabuf->resv,
			      DMA_RESV_USAGE_BOOKKEEP, false,
			      MAX_SCHEDULE_TIMEOUT);
	dma_resv_unlock(dmabuf->resv, NULL);

	// Wait for all importers to complete unmap
	wait_for_completion(&priv->unmapped_comp);

This works well, and an importer that continues to access the DMA-buf
after unmapping it is very buggy.

However, the final wait for unmap is effectively unbounded. Several
importers do not support invalidate_mappings() at all and won't unmap
until userspace triggers it.

This unbounded wait is not suitable for exporters like VFIO and RDMA tha
need to issue revoke as part of their normal operations.

Add dma_buf_attach_revocable() to allow exporters to determine the
difference between importers that can complete the above in bounded time,
and those that can't. It can be called inside the exporter's attach op to
reject incompatible importers.

Document these details about how dma_buf_invalidate_mappings() works and
what the required sequence is to achieve a full revocation.

Signed-off-by: Leon Romanovsky 
Reviewed-by: Christian König 
Signed-off-by: Christian König 
Link: https://lore.kernel.org/r/20260131-dmabuf-revoke-v7-6-463d956bd527@nvidia.com

Merge drm/drm-next into drm-misc-next

2026-02-23T10:48:20+00:00

Let's merge 7.0-rc1 to start the new drm-misc-next window

Signed-off-by: Maxime Ripard

Merge tag 'vfio-v7.0-rc1' of https://github.com/awilliam/linux-vfio

2026-02-12T23:52:39+00:00

Pull VFIO updates from Alex Williamson:
 "A small cycle with the bulk in selftests and reintroducing poison
  handling in the nvgrace-gpu driver. The rest are fixes, cleanups, and
  some dmabuf structure consolidation.

   - Update outdated mdev comment referencing the renamed
     mdev_type_add() function (Julia Lawall)

   - Introduce selftest support for IOMMU mapping of PCI MMIO BARs (Alex
     Mastro)

   - Relax selftest assertion relative to differences in huge page
     handling between legacy (v1) TYPE1 IOMMU mapping behavior and the
     compatibility mode supported by IOMMUFD (David Matlack)

   - Reintroduce memory poison handling support for non-struct-page-
     backed memory in the nvgrace-gpu variant driver (Ankit Agrawal)

   - Replace dma_buf_phys_vec with phys_vec to avoid duplicate structure
     and semantics (Leon Romanovsky)

   - Add missing upstream bridge locking across PCI function reset,
     resolving an assertion failure when secondary bus reset is used to
     provide that reset (Anthony Pighin)

   - Fixes to hisi_acc vfio-pci variant driver to resolve corner case
     issues related to resets, repeated migration, and error injection
     scenarios (Longfang Liu, Weili Qian)

   - Restrict vfio selftest builds to arm64 and x86_64, resolving
     compiler warnings on 32-bit archs (Ted Logan)

   - Un-deprecate the fsl-mc vfio bus driver as a new maintainer has
     stepped up (Ioana Ciornei)"

* tag 'vfio-v7.0-rc1' of https://github.com/awilliam/linux-vfio:
  vfio/fsl-mc: add myself as maintainer
  vfio: selftests: only build tests on arm64 and x86_64
  hisi_acc_vfio_pci: fix the queue parameter anomaly issue
  hisi_acc_vfio_pci: resolve duplicate migration states
  hisi_acc_vfio_pci: update status after RAS error
  hisi_acc_vfio_pci: fix VF reset timeout issue
  vfio/pci: Lock upstream bridge for vfio_pci_core_disable()
  types: reuse common phys_vec type instead of DMABUF open‑coded variant
  vfio/nvgrace-gpu: register device memory for poison handling
  mm: add stubs for PFNMAP memory failure registration functions
  vfio: selftests: Drop IOMMU mapping size assertions for VFIO_TYPE1_IOMMU
  vfio: selftests: Add vfio_dma_mapping_mmio_test
  vfio: selftests: Align BAR mmaps for efficient IOMMU mapping
  vfio: selftests: Centralize IOMMU mode name definitions
  vfio/mdev: update outdated comment

dma-buf: Rename dma_buf_move_notify() to dma_buf_invalidate_mappings()

2026-01-27T09:44:30+00:00

Along with renaming the .move_notify() callback, rename the corresponding
dma-buf core function. This makes the expected behavior clear to exporters
calling this function.

Signed-off-by: Leon Romanovsky 
Reviewed-by: Christian König 
Link: https://lore.kernel.org/r/20260124-dmabuf-revoke-v5-2-f98fca917e96@nvidia.com
Signed-off-by: Christian König

dma-buf: Rename .move_notify() callback to a clearer identifier

2026-01-27T09:43:55+00:00

Rename the .move_notify() callback to .invalidate_mappings() to make its
purpose explicit and highlight that it is responsible for invalidating
existing mappings.

Suggested-by: Christian König 
Reviewed-by: Christian König 
Signed-off-by: Leon Romanovsky 
Link: https://lore.kernel.org/r/20260124-dmabuf-revoke-v5-1-f98fca917e96@nvidia.com
Signed-off-by: Christian König

types: reuse common phys_vec type instead of DMABUF open‑coded variant

2026-01-19T17:13:29+00:00

After commit fcf463b92a08 ("types: move phys_vec definition to common header"),
we can use the shared phys_vec type instead of the DMABUF‑specific
dma_buf_phys_vec, which duplicated the same structure and semantics.

Signed-off-by: Leon Romanovsky 
Reviewed-by: Kevin Tian 
Reviewed-by: Jason Gunthorpe 
Link: https://lore.kernel.org/r/20260107-convert-to-pvec-v1-1-6e3ab8079708@nvidia.com
Signed-off-by: Alex Williamson

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