linux-kernel - [PATCH v12 0/3] rust: add dma coherent allocator abstraction

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Message-ID: <20250224115007.2072043-1-abdiel.janulgue@gmail.com>
Date: Mon, 24 Feb 2025 13:49:04 +0200
From: Abdiel Janulgue <abdiel.janulgue@...il.com>
To: aliceryhl@...gle.com,
	dakr@...nel.org,
	robin.murphy@....com,
	daniel.almeida@...labora.com,
	rust-for-linux@...r.kernel.org
Cc: Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>,
	Boqun Feng <boqun.feng@...il.com>,
	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <benno.lossin@...ton.me>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Trevor Gross <tmgross@...ch.edu>,
	Valentin Obst <kernel@...entinobst.de>,
	linux-kernel@...r.kernel.org (open list),
	Christoph Hellwig <hch@....de>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	airlied@...hat.com,
	iommu@...ts.linux.dev (open list:DMA MAPPING HELPERS),
	Abdiel Janulgue <abdiel.janulgue@...il.com>
Subject: [PATCH v12 0/3] rust: add dma coherent allocator abstraction

This series adds the rust bindings for the dma coherent allocator which
is needed for nova-core[0]. This is tested on a Nvidia GA104 GPU device
using PoC code which parses and loads the GSP firmware via DMA.

Changes since v11:
- Ensure robust handling for potential pointer arithmetic overflows
  in bounds checking (Petr Tesařík).
- Add dma mask helpers (Daniel Almeida).
- Clarification in the safety aspects of the as_slice/as_slice_mut API,
  Use ManuallyDrop trait as a replacement for into_parts(),
  Add dma_read!/dma_write! helper macros (Alice Ryhl).
- Link to v11: https://lore.kernel.org/lkml/20250123104333.1340512-1-abdiel.janulgue@gmail.com/

Changes since v10:
- rename read() to as_slice() (Boqun Feng)
- Do a bitwise copy of ARef<Device> in into_parts() when returning the
  device reference (Alice Ryhl).

Changes since v9:
- Use ARef<Device> in the constructor arguments, docs clarification avoid
  manually dropping the refcount for the device in into_parts(), use
  add() instead of wrapping_add() in the pointer arithmetic for performance
  (Alice Ryhl).

Changes since v8:
- Add MAINTAINERS entry
- Fix build issues due to switch from core::ffi to crate:ffi in bindgen.
- Ensure the wrapped attribute is non-pub in struct Attrs, declare it 
  #[repr(transparent)] as well (Daniel Sedlak)

Changes since v7:
- Remove cpu_buf() and cpu_buf_mut() as exporting a r/w interface via
  a slice is undefined behaviour due to slice's requirement that the
  underlying pointer should not be modified (Alice Ryhl, Robin Murphy).
- Reintroduce r/w helpers instead which includes proper safety
  invariants (Daniel Almeida).

Changes since v6:
- Include the dma_attrs in the constructor, use alloc::Flags as inpiration

Changes since v5:
- Remove unnecessary lifetime annotation when returning the CPU buffer.

Changes since v4:
- Documentation and example fixes, use Markdown formatting (Miguel Ojeda).
- Discard read()/write() helpers to remove bound on Copy and fix overhead
  (Daniel Almeida).
- Improve error-handling in the constructor block (Andreas Hindborg).

Changes since v3:
- Reject ZST types by checking the type size in the constructor in
  addition to requiring FromBytes/AsBytes traits for the type (Alice Ryhl).

Changes since v2:
- Fixed missing header for generating the bindings.

Changes since v1:
- Fix missing info in commit log where EOVERFLOW is used.
- Restrict the dma coherent allocator to numeric types for now for valid
  behaviour (Daniel Almeida).
- Build slice dynamically.

[0] https://lore.kernel.org/lkml/20250131220432.17717-1-dakr@kernel.org/

Abdiel Janulgue (3):
  rust: error: Add EOVERFLOW
  rust: add dma coherent allocator abstraction.
  MAINTAINERS: add entry for Rust dma mapping helpers device driver API

 MAINTAINERS                     |  12 +
 rust/bindings/bindings_helper.h |   1 +
 rust/helpers/dma.c              |  14 ++
 rust/helpers/helpers.c          |   1 +
 rust/kernel/dma.rs              | 411 ++++++++++++++++++++++++++++++++
 rust/kernel/error.rs            |   1 +
 rust/kernel/lib.rs              |   1 +
 7 files changed, 441 insertions(+)
 create mode 100644 rust/helpers/dma.c
 create mode 100644 rust/kernel/dma.rs


base-commit: beeb78d46249cab8b2b8359a2ce8fa5376b5ad2d
-- 
2.43.0