Re: [PATCH 08/13] gpu: nova-core: gsp: ensure LibOS DMA allocation lives long enough

[Alistair Popple]

On 2026-06-16 at 00:40 +1000, Eliot Courtney <ecourtney@xxxxxxxxxx> wrote...
> Currently, `GspSequencer` stores a raw DMA handle. Instead, store a
> reference to `Coherent` to statically ensure that the allocation lives
> long enough.

I'm thinking it would be rather hard to hit this in practice as running the
GspSequencer takes a reference to the command queue which is contained within
the same data structure as the DMA handle anyway.

Still it's much nicer not to rely on this detail which could change and to be
explicit instead so:

Reviewed-by: Alistair Popple <apopple@xxxxxxxxxx>

> Signed-off-by: Eliot Courtney <ecourtney@xxxxxxxxxx>
> ---
>  drivers/gpu/nova-core/gsp/hal/tu102.rs |  2 +-
>  drivers/gpu/nova-core/gsp/sequencer.rs | 18 +++++++++++-------
>  2 files changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/nova-core/gsp/hal/tu102.rs b/drivers/gpu/nova-core/gsp/hal/tu102.rs
> index eb7166148cc9..1e08c482fd39 100644
> --- a/drivers/gpu/nova-core/gsp/hal/tu102.rs
> +++ b/drivers/gpu/nova-core/gsp/hal/tu102.rs
> @@ -344,7 +344,7 @@ fn post_boot(
>          // Create and run the GSP sequencer.
>          let seq_params = GspSequencerParams {
>              bootloader_app_version: gsp_fw.bootloader.app_version,
> -            libos_dma_handle: gsp.libos.dma_handle(),
> +            libos: &gsp.libos,
>              gsp_falcon,
>              sec2_falcon,
>              dev,
> diff --git a/drivers/gpu/nova-core/gsp/sequencer.rs b/drivers/gpu/nova-core/gsp/sequencer.rs
> index e0850d21adca..ddb6abc45a37 100644
> --- a/drivers/gpu/nova-core/gsp/sequencer.rs
> +++ b/drivers/gpu/nova-core/gsp/sequencer.rs
> @@ -6,6 +6,7 @@
>  
>  use kernel::{
>      device,
> +    dma::Coherent,
>      io::{
>          poll::read_poll_timeout,
>          Io, //
> @@ -31,6 +32,7 @@
>              MessageFromGsp, //
>          },
>          fw,
> +        LibosMemoryRegionInitArgument, //
>      },
>      num::FromSafeCast,
>      sbuffer::SBufferIter,
> @@ -136,8 +138,8 @@ pub(crate) struct GspSequencer<'a> {
>      sec2_falcon: &'a Falcon<Sec2>,
>      /// GSP falcon for core operations.
>      gsp_falcon: &'a Falcon<Gsp>,
> -    /// LibOS DMA handle address.
> -    libos_dma_handle: u64,
> +    /// LibOS memory region init arguments.
> +    libos: &'a Coherent<[LibosMemoryRegionInitArgument]>,
>      /// Bootloader application version.
>      bootloader_app_version: u32,
>      /// Device for logging.
> @@ -233,11 +235,13 @@ fn run(&self, seq: &GspSequencer<'_>) -> Result {
>                  // Reset the GSP to prepare it for resuming.
>                  seq.gsp_falcon.reset(seq.bar)?;
>  
> +                let libos_dma_handle = seq.libos.dma_handle();
> +
>                  // Write the libOS DMA handle to GSP mailboxes.
>                  seq.gsp_falcon.write_mailboxes(
>                      seq.bar,
> -                    Some(seq.libos_dma_handle as u32),
> -                    Some((seq.libos_dma_handle >> 32) as u32),
> +                    Some(libos_dma_handle as u32),
> +                    Some((libos_dma_handle >> 32) as u32),
>                  );
>  
>                  // Start the SEC2 falcon which will trigger GSP-RM to resume on the GSP.
> @@ -342,8 +346,8 @@ fn iter(&self) -> GspSeqIter<'_> {
>  pub(crate) struct GspSequencerParams<'a> {
>      /// Bootloader application version.
>      pub(crate) bootloader_app_version: u32,
> -    /// LibOS DMA handle address.
> -    pub(crate) libos_dma_handle: u64,
> +    /// LibOS memory region init arguments.
> +    pub(crate) libos: &'a Coherent<[LibosMemoryRegionInitArgument]>,
>      /// GSP falcon for core operations.
>      pub(crate) gsp_falcon: &'a Falcon<Gsp>,
>      /// SEC2 falcon for core operations.
> @@ -369,7 +373,7 @@ pub(crate) fn run(cmdq: &Cmdq, params: GspSequencerParams<'a>) -> Result {
>              bar: params.bar,
>              sec2_falcon: params.sec2_falcon,
>              gsp_falcon: params.gsp_falcon,
> -            libos_dma_handle: params.libos_dma_handle,
> +            libos: params.libos,
>              bootloader_app_version: params.bootloader_app_version,
>              dev: params.dev,
>          };
> 
> -- 
> 2.54.0
>