Message-Id: <DE99VWCDFB64.1CXOJAOU0JC93@nvidia.com>
Date: Sat, 15 Nov 2025 21:38:17 +0900
From: "Alexandre Courbot" <acourbot@...dia.com>
To: "Joel Fernandes" <joelagnelf@...dia.com>,
 <linux-kernel@...r.kernel.org>, <rust-for-linux@...r.kernel.org>,
 <dri-devel@...ts.freedesktop.org>, "Danilo Krummrich" <dakr@...nel.org>,
 "Alexandre Courbot" <acourbot@...dia.com>
Cc: "Alistair Popple" <apopple@...dia.com>, "Miguel Ojeda"
 <ojeda@...nel.org>, "Alex Gaynor" <alex.gaynor@...il.com>, "Boqun Feng"
 <boqun.feng@...il.com>, "Gary Guo" <gary@...yguo.net>,
 <bjorn3_gh@...tonmail.com>, "Benno Lossin" <lossin@...nel.org>, "Andreas
 Hindborg" <a.hindborg@...nel.org>, "Alice Ryhl" <aliceryhl@...gle.com>,
 "Trevor Gross" <tmgross@...ch.edu>, "David Airlie" <airlied@...il.com>,
 "Simona Vetter" <simona@...ll.ch>, "Maarten Lankhorst"
 <maarten.lankhorst@...ux.intel.com>, "Maxime Ripard" <mripard@...nel.org>,
 "Thomas Zimmermann" <tzimmermann@...e.de>, "John Hubbard"
 <jhubbard@...dia.com>, "Timur Tabi" <ttabi@...dia.com>,
 <joel@...lfernandes.org>, "Daniel Almeida" <daniel.almeida@...labora.com>,
 <nouveau@...ts.freedesktop.org>, "Nouveau"
 <nouveau-bounces@...ts.freedesktop.org>
Subject: Re: [PATCH v5 13/13] gpu: nova-core: gsp: Retrieve GSP static info
 to gather GPU information

This one needed some rework.

On Sat Nov 15, 2025 at 4:55 AM JST, Joel Fernandes wrote:
> From: Alistair Popple <apopple@...dia.com>
>
> After GSP initialization is complete, retrieve the static configuration
> information from GSP-RM. This information includes GPU name, capabilities,
> memory configuration, and other properties. On some GPU variants, it is
> also required to do this for initialization to complete.
>
> Signed-off-by: Alistair Popple <apopple@...dia.com>
> Co-developed-by: Joel Fernandes <joelagnelf@...dia.com>
> Signed-off-by: Joel Fernandes <joelagnelf@...dia.com>
> ---
>  drivers/gpu/nova-core/gsp/boot.rs             |   7 +
>  drivers/gpu/nova-core/gsp/commands.rs         |  65 +++++++
>  drivers/gpu/nova-core/gsp/fw.rs               |   5 +
>  .../gpu/nova-core/gsp/fw/r570_144/bindings.rs | 163 ++++++++++++++++++
>  drivers/gpu/nova-core/nova_core.rs            |   1 +
>  drivers/gpu/nova-core/util.rs                 |  16 ++
>  6 files changed, 257 insertions(+)
>  create mode 100644 drivers/gpu/nova-core/util.rs
>
> diff --git a/drivers/gpu/nova-core/gsp/boot.rs b/drivers/gpu/nova-core/gsp/boot.rs
> index c0afafbf35f6..42a3abb9243d 100644
> --- a/drivers/gpu/nova-core/gsp/boot.rs
> +++ b/drivers/gpu/nova-core/gsp/boot.rs
> @@ -40,6 +40,7 @@
>          GspFwWprMeta, //
>      },
>      regs,
> +    util, //
>      vbios::Vbios,
>  };
>  
> @@ -237,6 +238,12 @@ pub(crate) fn boot(
>          GspSequencer::run(&mut self.cmdq, seq_params, Delta::from_secs(10))?;
>  
>          commands::gsp_init_done(&mut self.cmdq, Delta::from_secs(10))?;
> +        let info = commands::get_gsp_info(&mut self.cmdq, bar)?;
> +        dev_info!(
> +            pdev.as_ref(),
> +            "GPU name: {}\n",
> +            util::str_from_null_terminated(&info.gpu_name)
> +        );
>  
>          Ok(())
>      }
> diff --git a/drivers/gpu/nova-core/gsp/commands.rs b/drivers/gpu/nova-core/gsp/commands.rs
> index 07abfb54f9d7..6cb32e7d3436 100644
> --- a/drivers/gpu/nova-core/gsp/commands.rs
> +++ b/drivers/gpu/nova-core/gsp/commands.rs
> @@ -17,6 +17,7 @@
>  };
>  
>  use crate::{
> +    driver::Bar0,
>      gsp::{
>          cmdq::{
>              Cmdq,
> @@ -25,12 +26,25 @@
>          },
>          fw::{
>              commands::*,
> +            GspStaticConfigInfo_t,
>              MsgFunction, //
>          },
>      },
>      sbuffer::SBufferIter,
> +    util,
>  };
>  
> +// SAFETY: Padding is explicit and will not contain uninitialized data.
> +unsafe impl AsBytes for GspStaticConfigInfo_t {}
> +
> +// SAFETY: This struct only contains integer types for which all bit patterns
> +// are valid.
> +unsafe impl FromBytes for GspStaticConfigInfo_t {}
> +
> +pub(crate) struct GspStaticConfigInfo {
> +    pub gpu_name: [u8; 40],

This is probably meant to be `0x40`, as the `gpuNameString` bindings
member this is built from is 64-bytes long. Changing it to be 64-bytes
long.

> +}
> +
>  /// Message type for GSP initialization done notification.
>  struct GspInitDone {}
>  
> @@ -62,6 +76,57 @@ pub(crate) fn gsp_init_done(cmdq: &mut Cmdq, timeout: Delta) -> Result {
>      }
>  }
>  
> +impl MessageFromGsp for GspStaticConfigInfo {
> +    const FUNCTION: MsgFunction = MsgFunction::GetGspStaticInfo;
> +    type InitError = Infallible;
> +    type Message = GspStaticConfigInfo_t;
> +
> +    fn read(
> +        msg: &Self::Message,
> +        _sbuffer: &mut SBufferIter<array::IntoIter<&[u8], 2>>,
> +    ) -> Result<Self, Self::InitError> {
> +        let gpu_name_str = util::str_from_null_terminated(&msg.gpuNameString);
> +
> +        let mut gpu_name = [0u8; 40];
> +        let bytes = gpu_name_str.as_bytes();
> +        let copy_len = core::cmp::min(bytes.len(), gpu_name.len());
> +        gpu_name[..copy_len].copy_from_slice(&bytes[..copy_len]);
> +        gpu_name[copy_len] = b'\0';

We will want to move this into an `impl` block of `fw::commands`, since
`gpuNameString` is supposed to be firmware-specific and thus private.

But actually, do we even need this? When we print the GPU name in
`boot.rs`, we call `util::str_from_null_terminated` again on the bytes
array that we copied from here, but it is guaranteed to succeed if this
call succeeded as well. So I think (and successfully tested that) we can
just expose the raw bytes array as-is here, and extract the name from a
dedicated method.

> +
> +        Ok(GspStaticConfigInfo { gpu_name })
> +    }
> +}
> +
> +// SAFETY: This struct only contains integer types and fixed-size arrays for which
> +// all bit patterns are valid.
> +unsafe impl Zeroable for GspStaticConfigInfo_t {}
> +
> +struct GetGspInfo;
> +
> +impl CommandToGsp for GetGspInfo {
> +    const FUNCTION: MsgFunction = MsgFunction::GetGspStaticInfo;
> +    type Command = GspStaticConfigInfo_t;
> +    type InitError = Infallible;
> +
> +    fn init(&self) -> impl Init<Self::Command, Self::InitError> {
> +        init!(GspStaticConfigInfo_t {
> +            ..Zeroable::init_zeroed()
> +        })
> +    }
> +}
> +
> +pub(crate) fn get_gsp_info(cmdq: &mut Cmdq, bar: &Bar0) -> Result<GspStaticConfigInfo> {
> +    cmdq.send_command(bar, GetGspInfo)?;
> +
> +    loop {
> +        match cmdq.receive_msg::<GspStaticConfigInfo>(Delta::from_secs(5)) {
> +            Ok(info) => return Ok(info),
> +            Err(ERANGE) => continue,
> +            Err(e) => return Err(e),
> +        }
> +    }
> +}
> +
>  /// The `GspSetSystemInfo` command.
>  pub(crate) struct SetSystemInfo<'a> {
>      pdev: &'a pci::Device<device::Bound>,
> diff --git a/drivers/gpu/nova-core/gsp/fw.rs b/drivers/gpu/nova-core/gsp/fw.rs
> index 0cce54310c35..5b6a906ff5dc 100644
> --- a/drivers/gpu/nova-core/gsp/fw.rs
> +++ b/drivers/gpu/nova-core/gsp/fw.rs
> @@ -882,6 +882,11 @@ pub(crate) fn element_count(&self) -> u32 {
>      }
>  }
>  
> +pub(crate) use r570_144::{
> +    // GSP static configuration information.
> +    GspStaticConfigInfo_t, //
> +};

I've replaced this with a dedicated wrapping type and supporting code in
`fw::commands`, as is done for the other commands.

<snip>
> diff --git a/drivers/gpu/nova-core/util.rs b/drivers/gpu/nova-core/util.rs
> new file mode 100644
> index 000000000000..f1a4dea44c10
> --- /dev/null
> +++ b/drivers/gpu/nova-core/util.rs
> @@ -0,0 +1,16 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/// Converts a null-terminated byte array to a string slice.
> +///
> +/// Returns "invalid" if the bytes are not valid UTF-8 or not null-terminated.
> +pub(crate) fn str_from_null_terminated(bytes: &[u8]) -> &str {
> +    use kernel::str::CStr;
> +
> +    // Find the first null byte, then create a slice that includes it.
> +    bytes
> +        .iter()
> +        .position(|&b| b == 0)
> +        .and_then(|null_pos| CStr::from_bytes_with_nul(&bytes[..=null_pos]).ok())
> +        .and_then(|cstr| cstr.to_str().ok())
> +        .unwrap_or("invalid")
> +}

Let's not decide what the behavior on an invalid string is for the
caller, and let's make these cases detectable by returning an `Option`.
The caller can then `unwrap_or` it as it wants.

I'll apply these changes locally before pushing, as they are mostly
about harmonizing with the design of other existing commands and don't
change the behavior in any way.

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