Re: [PATCH v4 5/6] gpu: nova-core: add initial driver stub

["Alexandre Courbot" <acourbot@nvidia.com>]

Hi Danilo,

On Thu Feb 27, 2025 at 2:55 AM JST, Danilo Krummrich wrote:
> Add the initial nova-core driver stub.
>
> nova-core is intended to serve as a common base for nova-drm (the
> corresponding DRM driver) and the vGPU manager VFIO driver, serving as a
> hard- and firmware abstraction layer for GSP-based NVIDIA GPUs.
>
> The Nova project, including nova-core and nova-drm, in the long term,
> is intended to serve as the successor of Nouveau for all GSP-based GPUs.
>
> The motivation for both, starting a successor project for Nouveau and
> doing so using the Rust programming language, is documented in detail
> through a previous post on the mailing list [1], an LWN article [2] and a
> talk from LPC '24.
>
> In order to avoid the chicken and egg problem to require a user to
> upstream Rust abstractions, but at the same time require the Rust
> abstractions to implement the driver, nova-core kicks off as a driver
> stub and is subsequently developed upstream.
>
> Link: https://lore.kernel.org/dri-devel/Zfsj0_tb-0-tNrJy@cassiopeiae/T/#u [1]
> Link: https://lwn.net/Articles/990736/ [2]
> Link: https://youtu.be/3Igmx28B3BQ?si=sBdSEer4tAPKGpOs [3]
> Signed-off-by: Danilo Krummrich <dakr@kernel.org>
> ---
>  MAINTAINERS                        |  10 ++
>  drivers/gpu/Makefile               |   1 +
>  drivers/gpu/nova-core/Kconfig      |  14 ++
>  drivers/gpu/nova-core/Makefile     |   3 +
>  drivers/gpu/nova-core/driver.rs    |  47 ++++++
>  drivers/gpu/nova-core/firmware.rs  |  45 ++++++
>  drivers/gpu/nova-core/gpu.rs       | 225 +++++++++++++++++++++++++++++
>  drivers/gpu/nova-core/nova_core.rs |  19 +++
>  drivers/gpu/nova-core/regs.rs      |  55 +++++++
>  drivers/video/Kconfig              |   1 +
>  10 files changed, 420 insertions(+)
>  create mode 100644 drivers/gpu/nova-core/Kconfig
>  create mode 100644 drivers/gpu/nova-core/Makefile
>  create mode 100644 drivers/gpu/nova-core/driver.rs
>  create mode 100644 drivers/gpu/nova-core/firmware.rs
>  create mode 100644 drivers/gpu/nova-core/gpu.rs
>  create mode 100644 drivers/gpu/nova-core/nova_core.rs
>  create mode 100644 drivers/gpu/nova-core/regs.rs
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 1b0cc181db74..3c8a3b61af38 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -7438,6 +7438,16 @@ T:	git https://gitlab.freedesktop.org/drm/nouveau.git
>  F:	drivers/gpu/drm/nouveau/
>  F:	include/uapi/drm/nouveau_drm.h
>  
> +CORE DRIVER FOR NVIDIA GPUS [RUST]
> +M:	Danilo Krummrich <dakr@kernel.org>
> +L:	nouveau@lists.freedesktop.org
> +S:	Supported
> +Q:	https://patchwork.freedesktop.org/project/nouveau/
> +B:	https://gitlab.freedesktop.org/drm/nova/-/issues
> +C:	irc://irc.oftc.net/nouveau
> +T:	git https://gitlab.freedesktop.org/drm/nova.git nova-next
> +F:	drivers/gpu/nova-core/
> +
>  DRM DRIVER FOR OLIMEX LCD-OLINUXINO PANELS
>  M:	Stefan Mavrodiev <stefan@olimex.com>
>  S:	Maintained
> diff --git a/drivers/gpu/Makefile b/drivers/gpu/Makefile
> index 8997f0096545..36a54d456630 100644
> --- a/drivers/gpu/Makefile
> +++ b/drivers/gpu/Makefile
> @@ -5,3 +5,4 @@
>  obj-y			+= host1x/ drm/ vga/
>  obj-$(CONFIG_IMX_IPUV3_CORE)	+= ipu-v3/
>  obj-$(CONFIG_TRACE_GPU_MEM)		+= trace/
> +obj-$(CONFIG_NOVA_CORE)		+= nova-core/
> diff --git a/drivers/gpu/nova-core/Kconfig b/drivers/gpu/nova-core/Kconfig
> new file mode 100644
> index 000000000000..ad0c06756516
> --- /dev/null
> +++ b/drivers/gpu/nova-core/Kconfig
> @@ -0,0 +1,14 @@
> +config NOVA_CORE
> +	tristate "Nova Core GPU driver"
> +	depends on PCI
> +	depends on RUST
> +	depends on RUST_FW_LOADER_ABSTRACTIONS
> +	default n
> +	help
> +	  Choose this if you want to build the Nova Core driver for Nvidia
> +	  GPUs based on the GPU System Processor (GSP). This is true for Turing
> +	  and later GPUs.
> +
> +	  This driver is work in progress and may not be functional.
> +
> +	  If M is selected, the module will be called nova_core.
> diff --git a/drivers/gpu/nova-core/Makefile b/drivers/gpu/nova-core/Makefile
> new file mode 100644
> index 000000000000..2d78c50126e1
> --- /dev/null
> +++ b/drivers/gpu/nova-core/Makefile
> @@ -0,0 +1,3 @@
> +# SPDX-License-Identifier: GPL-2.0
> +
> +obj-$(CONFIG_NOVA_CORE) += nova_core.o
> diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
> new file mode 100644
> index 000000000000..63c19f140fbd
> --- /dev/null
> +++ b/drivers/gpu/nova-core/driver.rs
> @@ -0,0 +1,47 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +use kernel::{bindings, c_str, pci, prelude::*};
> +
> +use crate::gpu::Gpu;
> +
> +#[pin_data]
> +pub(crate) struct NovaCore {
> +    #[pin]
> +    pub(crate) gpu: Gpu,
> +}
> +
> +const BAR0_SIZE: usize = 8;
> +pub(crate) type Bar0 = pci::Bar<BAR0_SIZE>;
> +
> +kernel::pci_device_table!(
> +    PCI_TABLE,
> +    MODULE_PCI_TABLE,
> +    <NovaCore as pci::Driver>::IdInfo,
> +    [(
> +        pci::DeviceId::from_id(bindings::PCI_VENDOR_ID_NVIDIA, bindings::PCI_ANY_ID as _),
> +        ()
> +    )]
> +);
> +
> +impl pci::Driver for NovaCore {
> +    type IdInfo = ();
> +    const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
> +
> +    fn probe(pdev: &mut pci::Device, _info: &Self::IdInfo) -> Result<Pin<KBox<Self>>> {
> +        dev_dbg!(pdev.as_ref(), "Probe Nova Core GPU driver.\n");
> +
> +        pdev.enable_device_mem()?;
> +        pdev.set_master();
> +
> +        let bar = pdev.iomap_region_sized::<BAR0_SIZE>(0, c_str!("nova-core/bar0"))?;
> +
> +        let this = KBox::pin_init(
> +            try_pin_init!(Self {
> +                gpu <- Gpu::new(pdev, bar)?,
> +            }),
> +            GFP_KERNEL,
> +        )?;
> +
> +        Ok(this)
> +    }
> +}
> diff --git a/drivers/gpu/nova-core/firmware.rs b/drivers/gpu/nova-core/firmware.rs
> new file mode 100644
> index 000000000000..a94caa7cf8d3
> --- /dev/null
> +++ b/drivers/gpu/nova-core/firmware.rs
> @@ -0,0 +1,45 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +use crate::gpu;
> +use kernel::firmware;
> +
> +pub(crate) struct ModInfoBuilder<const N: usize>(firmware::ModInfoBuilder<N>);
> +
> +impl<const N: usize> ModInfoBuilder<N> {
> +    const fn make_entry_file(self, chipset: &[u8], fw: &[u8]) -> Self {
> +        let version = b"535.113.01";
> +
> +        ModInfoBuilder(
> +            self.0
> +                .prepare()
> +                .push(b"nvidia/")
> +                .push(chipset)
> +                .push(b"/gsp/")
> +                .push(fw)
> +                .push(b"-")
> +                .push(version)
> +                .push(b".bin"),
> +        )
> +    }
> +
> +    const fn make_entry_chipset(self, chipset: &[u8]) -> Self {
> +        self.make_entry_file(chipset, b"booter_load")
> +            .make_entry_file(chipset, b"booter_unload")
> +            .make_entry_file(chipset, b"bootloader")
> +            .make_entry_file(chipset, b"gsp")
> +    }
> +
> +    pub(crate) const fn create(
> +        module_name: &'static kernel::str::CStr,
> +    ) -> firmware::ModInfoBuilder<N> {
> +        let mut this = Self(firmware::ModInfoBuilder::new(module_name));
> +        let mut i = 0;
> +
> +        while i < gpu::Chipset::NAMES.len() {
> +            this = this.make_entry_chipset(gpu::Chipset::NAMES[i].as_bytes());
> +            i += 1;
> +        }
> +
> +        this.0
> +    }
> +}
> diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
> new file mode 100644
> index 000000000000..7693a5df0dc1
> --- /dev/null
> +++ b/drivers/gpu/nova-core/gpu.rs
> @@ -0,0 +1,225 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +use kernel::{
> +    device, devres::Devres, error::code::*, firmware, fmt, pci, prelude::*, str::BStr, str::CString,
> +};
> +
> +use crate::driver::Bar0;
> +use crate::regs;
> +use core::fmt;
> +
> +const fn to_lowercase_bytes<const N: usize>(s: &str) -> [u8; N] {
> +    let src = s.as_bytes();
> +    let mut dst = [0; N];
> +    let mut i = 0;
> +
> +    while i < src.len() && i < N {
> +        dst[i] = (src[i] as char).to_ascii_lowercase() as u8;
> +        i += 1;
> +    }
> +
> +    dst
> +}
> +
> +macro_rules! define_chipset {
> +    ({ $($variant:ident = $value:expr),* $(,)* }) =>
> +    {
> +        /// Enum representation of the GPU chipset.
> +        #[derive(fmt::Debug)]
> +        pub(crate) enum Chipset {
> +            $($variant = $value),*,
> +        }
> +
> +        impl Chipset {
> +            pub(crate) const ALL: &'static [Chipset] = &[
> +                $( Chipset::$variant, )*
> +            ];
> +
> +            pub(crate) const NAMES: [&BStr; Self::ALL.len()] = [
> +                $( BStr::from_bytes(
> +                        to_lowercase_bytes::<{ stringify!($variant).len() }>(
> +                            stringify!($variant)
> +                        ).as_slice()
> +                ), )*
> +            ];
> +        }
> +    }
> +}
> +
> +define_chipset!({
> +    // Turing
> +    TU102 = 0x162,
> +    TU104 = 0x164,
> +    TU106 = 0x166,
> +    TU117 = 0x167,
> +    TU116 = 0x168,
> +    // Ampere
> +    GA102 = 0x172,
> +    GA103 = 0x173,
> +    GA104 = 0x174,
> +    GA106 = 0x176,
> +    GA107 = 0x177,
> +    // Ada
> +    AD102 = 0x192,
> +    AD103 = 0x193,
> +    AD104 = 0x194,
> +    AD106 = 0x196,
> +    AD107 = 0x197,
> +});
> +
> +impl Chipset {
> +    pub(crate) fn arch(&self) -> Architecture {
> +        match self {
> +            Self::TU102 | Self::TU104 | Self::TU106 | Self::TU117 | Self::TU116 => {
> +                Architecture::Turing
> +            }
> +            Self::GA102 | Self::GA103 | Self::GA104 | Self::GA106 | Self::GA107 => {
> +                Architecture::Ampere
> +            }
> +            Self::AD102 | Self::AD103 | Self::AD104 | Self::AD106 | Self::AD107 => {
> +                Architecture::Ada
> +            }
> +        }
> +    }
> +}
> +
> +// TODO
> +//
> +// The resulting strings are used to generate firmware paths, hence the
> +// generated strings have to be stable.
> +//
> +// Hence, replace with something like strum_macros derive(Display).
> +//
> +// For now, redirect to fmt::Debug for convenience.
> +impl fmt::Display for Chipset {
> +    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
> +        write!(f, "{:?}", self)
> +    }
> +}
> +
> +// TODO replace with something like derive(FromPrimitive)
> +impl TryFrom<u32> for Chipset {
> +    type Error = kernel::error::Error;
> +
> +    fn try_from(value: u32) -> Result<Self, Self::Error> {
> +        match value {
> +            0x162 => Ok(Chipset::TU102),
> +            0x164 => Ok(Chipset::TU104),
> +            0x166 => Ok(Chipset::TU106),
> +            0x167 => Ok(Chipset::TU117),
> +            0x168 => Ok(Chipset::TU116),
> +            0x172 => Ok(Chipset::GA102),
> +            0x173 => Ok(Chipset::GA103),
> +            0x174 => Ok(Chipset::GA104),
> +            0x176 => Ok(Chipset::GA106),
> +            0x177 => Ok(Chipset::GA107),
> +            0x192 => Ok(Chipset::AD102),
> +            0x193 => Ok(Chipset::AD103),
> +            0x194 => Ok(Chipset::AD104),
> +            0x196 => Ok(Chipset::AD106),
> +            0x197 => Ok(Chipset::AD107),
> +            _ => Err(ENODEV),
> +        }
> +    }
> +}

I know this is probably temporary anyway, but since there is a macro now you can simplify this implementation by making part of it:

		impl TryFrom<u32> for Chipset {
				type Error = kernel::error::Error;

				fn try_from(value: u32) -> Result<Self, Self::Error> {
						match value {
								$( $value => Ok(Chipset::$variant), )*
								_ => Err(ENODEV),
						}
				}
		}