Re: [PATCH v2 0/2] rust: introduce abstractions for fwctl

[Zhi Wang <zhiw@nvidia.com>]

On Thu, 22 Jan 2026 22:32:03 +0100
"Danilo Krummrich" <dakr@kernel.org> wrote:

> (Cc: Jason)
> 
> Looks like you used the recipient list of another patch series by
> accident. :)
> 

Sorry my bad. I would prepare a new script for this series.

Z.

> On Thu Jan 22, 2026 at 9:42 PM CET, Zhi Wang wrote:
> > In the NVIDIA vGPU RFC [1], the vGPU type blobs must be provided to
> > the GSP before userspace can enumerate available vGPU types and create
> > vGPU instances. The original design relied on the firmware loading
> > interface, but fwctl is a more natural fit for this use case, as it is
> > designed for uploading configuration or firmware data required before
> > the device becomes operational.
> >
> > This patch introduces a Rust abstraction over the fwctl subsystem,
> > providing safe and idiomatic bindings.
> >
> > The new `fwctl` module allows Rust drivers to integrate with the
> > existing C-side fwctl core through a typed trait interface. It
> > provides:
> >
> >   - `Operations` trait — defines driver-specific operations such as
> >     `open_uctx()`, `close_uctx()`, `info()`, and `fw_rpc()`.  
> >     Each Rust driver implements this trait to describe its own per-FD
> >     user-context behavior and RPC handling.
> >
> >   - `UserCtx<T>` — a generic wrapper around `struct fwctl_uctx`
> >     embedding driver-specific context data, providing safe conversion
> >     from raw C pointers and access to the parent device.
> >
> >   - `Registration<T>` — safe registration and automatic unregistration
> >     of `struct fwctl_device` objects using the kernel's device model.
> >
> >   - `VTable<T>` — a static vtable bridging C callbacks and Rust
> >     trait methods, ensuring type safety across the FFI boundary.
> >
> > `rust/kernel/lib.rs` is updated to conditionally include this module
> > under `CONFIG_FWCTL`.
> >
> > The repo with the patches can be found at [2].
> >
> > v2:
> >
> > - Don't open fwctl_put(). Add a rust helper. (Jason/Danilo)
> > - Wrap Registration with Devres to guarantee proper lifetime
> > management. (Jason/Danilo)
> > - Rename FwctlOps to Operations, FwctlUserCtx to UserCtx, FwctlDevice
> > to Device. (Danilo)
> > - Use fwctl::DeviceType enum instead of raw u32 for DEVICE_TYPE.
> > (Danilo)
> > - Change fwctl_uctx field in UserCtx to Opaque<bindings::fwctl_uctx>
> > and make it private. (Danilo)
> > - Provide Deref and DerefMut implementations for UserCtx::uctx.
> > (Danilo)
> > - Add UserCtx::parent_device_from_raw() to simplify parent device
> > access.
> > - Use cast() and cast_mut() instead of manual pointer casts. (Danilo)
> > - Implement AlwaysRefCounted for Device and use ARef<Device> in
> >   Registration. (Danilo)
> > - Add rust_helper_fwctl_get() for reference counting.
> > - Improve safety comments for slice::from_raw_parts_mut() in
> >   fw_rpc_callback. (Danilo)
> > - Convert imports to vertical style.
> > - Fix all clippy warnings.
> >
> > v1:
> >
> > - Initial submission introducing fwctl Rust abstractions.
> >
> > [1]
> > https://lore.kernel.org/all/20250903221111.3866249-1-zhiw@nvidia.com/
> > [2]
> > https://github.com/zhiwang-nvidia/driver-core/tree/fwctl-rust-abstraction-v2
> >
> > Zhi Wang (2):
> >   rust: introduce abstractions for fwctl
> >   samples: rust: fwctl: add sample code for fwctl
> >
> >  drivers/fwctl/Kconfig             |  12 +
> >  include/uapi/fwctl/fwctl.h        |   1 +
> >  rust/bindings/bindings_helper.h   |   1 +
> >  rust/helpers/fwctl.c              |  17 ++
> >  rust/helpers/helpers.c            |   3 +-
> >  rust/kernel/fwctl.rs              | 456 ++++++++++++++++++++++++++++++
> >  rust/kernel/lib.rs                |   2 +
> >  samples/rust/Kconfig              |  11 +
> >  samples/rust/Makefile             |   1 +
> >  samples/rust/rust_driver_fwctl.rs | 136 +++++++++
> >  10 files changed, 639 insertions(+), 1 deletion(-)
> >  create mode 100644 rust/helpers/fwctl.c
> >  create mode 100644 rust/kernel/fwctl.rs
> >  create mode 100644 samples/rust/rust_driver_fwctl.rs
> >
> > -- 
> > 2.51.0
>