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  • Daniel Almeida Daniel Almeida dwlsalmeida
1 author
  1. Apr 03, 2025
    • Asahi Lina's avatar
      rust: drm: Add GPUVM abstraction · 201dd231
      Asahi Lina authored and Daniel Almeida's avatar Daniel Almeida committed 
      
Add a GPUVM abstraction to be used by Rust GPU drivers.

GPUVM keeps track of a GPU's virtual address (VA) space and manages the
corresponding virtual mappings represented by "GPU VA" objects. It also
keeps track of the mapping's backing GEM buffers.

This initial version only support synchronous operations. In other words,
we do not support the use case where the operations are pre-built and
handed over to the driver.

We also do not support using a driver-specific lock in order to serialize
the gpuva list for a given GEM object. This has to be the GEM object resv,
which is the default behavior in C.

Similarly to the C code, locking is left to the driver. This means that the
driver should make sure that the VM's interval tree is protected against
concurrent access. In Rust, we encode this requirement by requiring a
generic Guard type in GpuVm::lock(), which is a similar approach as the one
taken by CondVar.

It is up to drivers to make sure that the guard indeed provides the
required locking. Any operations that modifies the interval tree is only
available after the VM has been locked as per above.

Signed-off-by: default avatarAsahi Lina <lina@asahilina.net>
Co-developed-by: default avatarDaniel Almeida <daniel.almeida@collabora.com>
Signed-off-by: default avatarDaniel Almeida <daniel.almeida@collabora.com>
      201dd231
  3. Mar 24, 2025
  5. Mar 20, 2025
    • Daniel Almeida's avatar
      Add a Rust GPUVM abstraction · 6755a070
      Daniel Almeida authored 
      # Describe the purpose of this series. The information you put here
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# very detailed and link to any relevant discussions or sites that the
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# letter will be appended to the "under-the-cut" portion of the patch.

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# use them to add notes or reminders to yourself. If you want to use
# markdown headers in your cover letter, start the line with ">#".

# You can add trailers to the cover letter. Any email addresses found in
# these trailers will be added to the addresses specified/generated
# during the b4 send stage. You can also run "b4 prep --auto-to-cc" to
# auto-populate the To: and Cc: trailers based on the code being
# modified.

Changes from v0:
  This version changes how `LockedGpuVm` operates. The previous code assumed
that the interval tree would be protected if all the associated GEM's resvs
were locked, but this is completely unrelated. In fact, this initial version
only aims to support the core VA range management feature of GPUVM, and not any
of the "convenience" functions like "exec_lock()" and friends, so this function
was removed accordingly.
  
  LockedGpuVm is now produced by a call to GpuVm::lock(). This takes a generic
guard type to signal that the driver-specific locks have been acquired in order
to protect the VMs tree, and hence its view of the address space. This approach
is somewhat similar to CondVar, but also incurs in the same pitfall: it is up
to the caller to give meaning to the guard by ensuring that it actually
protects against concurrent access to the VM. Maybe this is a good candidate to
the upcoming "Pitfall" docs section?

  Note that LockedGpuVm::obj was removed. I'm not really sure why this field
was there in the first place, but callers should indicate the object through
the sm_map() and sm_unmap() APIs instead.

  I am not sure why GpuVm::inner uses UnsafeCell, though. I did not touch this
so that we can first discuss whether UnsafeCell is really needed.

  The docs were also updated. Care was taken to reuse the C documentation as
much as possible.

  Itemized changes: 

- Rebased on top of nova-drm
  - Use `srctree` in the docs
  - Add docs as appropriate and remove #[allow(missing_docs)]
  - Remove `impl DriverGpuVa for ()`. Drivers can to that themselves, if they want.
  - Added #[inline] to getters, as Rust cannot inline across crates otherwise (unless this changed recently?)
  - Exposed `drm_gpuva_op_unmap::keep`.
  - Removed `pub(super)` from unsafe fns meant to be called from the C code. 
  - Added "# Safety" blocks to the above.
  - Removed `exec_lock_gem_object()`.
  - Removed `exec_lock()`
  - Removed `LockedGpuVm::vm_exec`. This initial version does not support `exec` calls at all.
  - By the same token, removed `LockedGpuVm::drop()`
  - Removed `LockedGpuVm::obj`. This object has to be passed explicitly.

To: Miguel Ojeda <ojeda@kernel.org>
To: Alex Gaynor <alex.gaynor@gmail.com>
To: Boqun Feng <boqun.feng@gmail.com>
To: Gary Guo <gary@garyguo.net>
To: Björn Roy Baron <bjorn3_gh@protonmail.com>
To: Benno Lossin <benno.lossin@proton.me>
To: Andreas Hindborg <a.hindborg@kernel.org>
To: Alice Ryhl <aliceryhl@google.com>
To: Trevor Gross <tmgross@umich.edu>
To: Sumit Semwal <sumit.semwal@linaro.org>
To: Christian König <christian.koenig@amd.com>
To: Boris Brezillon <boris.brezillon@collabora.com>
Cc: linux-kernel@vger.kernel.org
Cc: rust-for-linux@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org

--- b4-submit-tracking ---
# This section is used internally by b4 prep for tracking purposes.
{
  "series": {
    "revision": 1,
    "change-id": "20250320-gpuvm-29d3e0726f34",
    "prefixes": []
  }
}
      6755a070
  7. Mar 19, 2025
  9. Mar 14, 2025
    • Danilo Krummrich's avatar
      rust: platform: fix unrestricted &mut platform::Device · a00823c7
      Danilo Krummrich authored 
      
As by now, platform::Device is implemented as:

	#[derive(Clone)]
	pub struct Device(ARef<device::Device>);

This may be convenient, but has the implication that drivers can call
device methods that require a mutable reference concurrently at any
point of time.

Instead define platform::Device as

	pub struct Device<Ctx: DeviceContext = Normal>(
		Opaque<bindings::platform_dev>,
		PhantomData<Ctx>,
	);

and manually implement the AlwaysRefCounted trait.

With this we can implement methods that should only be called from
bus callbacks (such as probe()) for platform::Device<Core>. Consequently,
we make this type accessible in bus callbacks only.

Arbitrary references taken by the driver are still of type
ARef<platform::Device> and hence don't provide access to methods that are
reserved for bus callbacks.

Fixes: 683a63be ("rust: platform: add basic platform device / driver abstractions")
Reviewed-by: default avatarBenno Lossin <benno.lossin@proton.me>
Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
      a00823c7
    • Danilo Krummrich's avatar
      rust: pci: fix unrestricted &mut pci::Device · 2020e63b
      Danilo Krummrich authored 
      
As by now, pci::Device is implemented as:

	#[derive(Clone)]
	pub struct Device(ARef<device::Device>);

This may be convenient, but has the implication that drivers can call
device methods that require a mutable reference concurrently at any
point of time.

Instead define pci::Device as

	pub struct Device<Ctx: DeviceContext = Normal>(
		Opaque<bindings::pci_dev>,
		PhantomData<Ctx>,
	);

and manually implement the AlwaysRefCounted trait.

With this we can implement methods that should only be called from
bus callbacks (such as probe()) for pci::Device<Core>. Consequently, we
make this type accessible in bus callbacks only.

Arbitrary references taken by the driver are still of type
ARef<pci::Device> and hence don't provide access to methods that are
reserved for bus callbacks.

Fixes: 1bd8b6b2 ("rust: pci: add basic PCI device / driver abstractions")
Reviewed-by: default avatarBenno Lossin <benno.lossin@proton.me>
Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
      2020e63b
    • Danilo Krummrich's avatar
      rust: device: implement device context marker · a3e42248
      Danilo Krummrich authored 
      
Some bus device functions should only be called from bus callbacks,
such as probe(), remove(), resume(), suspend(), etc.

To ensure this add device context marker structs, that can be used as
generics for bus device implementations.

Reviewed-by: default avatarBenno Lossin <benno.lossin@proton.me>
Suggested-by: default avatarBenno Lossin <benno.lossin@proton.me>
Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
      a3e42248
    • Danilo Krummrich's avatar
      rust: pci: use to_result() in enable_device_mem() · 4893349c
      Danilo Krummrich authored 
      
Simplify enable_device_mem() by using to_result() to handle the return
value of the corresponding FFI call.

Reviewed-by: default avatarBenno Lossin <benno.lossin@proton.me>
Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
      4893349c
  11. Mar 09, 2025
  13. Mar 02, 2025