Re: [PATCH v9 06/31] gpu: nova-core: Hopper/Blackwell: skip GFW boot waiting

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

On Thu Mar 26, 2026 at 10:38 AM JST, John Hubbard wrote:
> Hopper and Blackwell GPUs use FSP-based secure boot and do not
> require waiting for GFW_BOOT completion. Move the GFW_BOOT wait
> into a GPU HAL so the decision and the wait both live in the HAL.
>
> Pre-Hopper families (Tu102 HAL) wait for GFW_BOOT completion.
> Hopper and later (Gh100 HAL) skip it and boot via FSP instead.
>
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
> ---
>  drivers/gpu/nova-core/gpu.rs     |  6 +++--
>  drivers/gpu/nova-core/gpu/hal.rs | 41 ++++++++++++++++++++++++++++++++
>  2 files changed, 45 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/gpu/nova-core/gpu/hal.rs
>
> diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
> index f70bfbda1614..8332ad67c0af 100644
> --- a/drivers/gpu/nova-core/gpu.rs
> +++ b/drivers/gpu/nova-core/gpu.rs
> @@ -21,11 +21,12 @@
>          Falcon, //
>      },
>      fb::SysmemFlush,
> -    gfw,
>      gsp::Gsp,
>      regs,
>  };
>  
> +mod hal;
> +
>  macro_rules! define_chipset {
>      ({ $($variant:ident = $value:expr),* $(,)* }) =>
>      {
> @@ -311,6 +312,7 @@ pub(crate) fn new<'a>(
>          spec: Spec,
>      ) -> impl PinInit<Self, Error> + 'a {
>          let dma_mask = spec.chipset().arch().dma_mask();
> +        let hal = hal::gpu_hal(spec.chipset());
>  
>          try_pin_init!(Self {
>              // We must wait for GFW_BOOT completion before doing any significant setup on the GPU.
> @@ -319,7 +321,7 @@ pub(crate) fn new<'a>(
>                  // still constructing it, so no concurrent DMA allocations can exist.
>                  unsafe { pdev.dma_set_mask_and_coherent(dma_mask)? };
>  
> -                gfw::wait_gfw_boot_completion(bar)
> +                hal.wait_gfw_boot_completion(bar)
>                      .inspect_err(|_| dev_err!(pdev, "GFW boot did not complete\n"))?;
>              },
>  
> diff --git a/drivers/gpu/nova-core/gpu/hal.rs b/drivers/gpu/nova-core/gpu/hal.rs
> new file mode 100644
> index 000000000000..164410992659
> --- /dev/null
> +++ b/drivers/gpu/nova-core/gpu/hal.rs
> @@ -0,0 +1,41 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +use kernel::prelude::*;
> +
> +use crate::{
> +    driver::Bar0,
> +    gfw,
> +    gpu::{
> +        Architecture,
> +        Chipset, //
> +    },
> +};
> +
> +pub(crate) trait GpuHal {
> +    /// Waits for GFW_BOOT completion if required by this hardware family.
> +    fn wait_gfw_boot_completion(&self, bar: &Bar0) -> Result;
> +}
> +
> +struct Tu102;
> +struct Gh100;
> +
> +impl GpuHal for Tu102 {
> +    fn wait_gfw_boot_completion(&self, bar: &Bar0) -> Result {
> +        gfw::wait_gfw_boot_completion(bar)
> +    }
> +}
> +
> +impl GpuHal for Gh100 {
> +    fn wait_gfw_boot_completion(&self, _bar: &Bar0) -> Result {
> +        Ok(())
> +    }
> +}

Please take a look at how other HALs are implemented: each HAL instance
is in its own module. That's not just a cosmetic choice; it allows us to
keep the chipset's specific HAL struct and its helpers completely
private and forces us to make code-sharing explicit. Furthermore, this
particular HAL is bound to grow, so let's split it properly from the
start.

If you do that it also makes more sense to use constants (contrary to
Gary's feedback on v8), if only to align with the rest of the driver.

Once this is done, making `gpu::hal::tu102` absorb the `gfw` module is
trivial, so let's do that while we are at it - having `gfw` as being
driver-wide makes little sense since it has a very limited role for a
specific subset of the chips we support.