Re: [PATCH 0/3] Add Rust abstraction for Maple Trees

["Liam R. Howlett" <Liam.Howlett@oracle.com>]

* Alice Ryhl <aliceryhl@google.com> [250726 09:23]:

Alice, Danilo, and others..

Sorry for the delay, I've been off for a few weeks.

I'm just digging my way out of the emails now, so I'll have a look at
this shortly.

Thanks,
Liam

> This will be used in the Tyr driver [1] to allocate from the GPU's VA
> space that is not owned by userspace, but by the kernel, for kernel GPU
> mappings.
> 
> Danilo tells me that in nouveau, the maple tree is used for keeping
> track of "VM regions" on top of GPUVM, and that he will most likely end
> up doing the same in the Rust Nova driver as well.
> 
> These abstractions intentionally do not expose any way to make use of
> external locking. You are required to use the internal spinlock. For
> now, we do not support loads that only utilize rcu for protection.
> 
> This contains some parts taken from Andrew Ballance's RFC [2] from
> April. However, it has also been reworked significantly compared to that
> RFC taking the use-cases in Tyr into account.
> 
> [1]: https://lore.kernel.org/r/20250627-tyr-v1-1-cb5f4c6ced46@collabora.com
> [2]: https://lore.kernel.org/r/20250405060154.1550858-1-andrewjballance@gmail.com
> 
> Signed-off-by: Alice Ryhl <aliceryhl@google.com>
> ---
> Alice Ryhl (3):
>       rust: maple_tree: add MapleTree
>       rust: maple_tree: add MapleTree::lock() and load()
>       rust: maple_tree: add MapleTreeAlloc
> 
>  MAINTAINERS               |   2 +
>  rust/helpers/helpers.c    |   1 +
>  rust/helpers/maple_tree.c |  14 ++
>  rust/kernel/lib.rs        |   1 +
>  rust/kernel/maple_tree.rs | 538 ++++++++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 556 insertions(+)
> ---
> base-commit: dff64b072708ffef23c117fa1ee1ea59eb417807
> change-id: 20250726-maple-tree-1af0803ac524
> 
> Best regards,
> -- 
> Alice Ryhl <aliceryhl@google.com>
>