On Wed Oct 8, 2025 at 2:12 AM CEST, Alistair Popple wrote:
> diff --git a/drivers/gpu/nova-core/gsp.rs b/drivers/gpu/nova-core/gsp.rs
> index 221281da1a45..63099df77348 100644
> --- a/drivers/gpu/nova-core/gsp.rs
> +++ b/drivers/gpu/nova-core/gsp.rs
> @@ -2,25 +2,94 @@
>
> mod boot;
>
> +use kernel::device;
> +use kernel::dma::CoherentAllocation;
> +use kernel::dma::DmaAddress;
> +use kernel::dma_write;
> +use kernel::pci;
> use kernel::prelude::*;
> use kernel::ptr::Alignment;
> +use kernel::transmute::AsBytes;
>
> pub(crate) use fw::{GspFwWprMeta, LibosParams};
>
> mod fw;
>
> +use fw::LibosMemoryRegionInitArgument;
> +
> pub(crate) const GSP_PAGE_SHIFT: usize = 12;
> pub(crate) const GSP_PAGE_SIZE: usize = 1 << GSP_PAGE_SHIFT;
> pub(crate) const GSP_HEAP_ALIGNMENT: Alignment = Alignment::new::<{ 1 << 20
> }>();
This looks like it could depend on the firmware version in the future, hence it
should probably defined somewhere in fw/ with a corresponding comment. The
actual version switch is fine to omit for now of course (we agreed to add the
infrastructure for the version switch subsequently).
> +/// Number of GSP pages to use in a RM log buffer.
> +const RM_LOG_BUFFER_NUM_PAGES: usize = 0x10;
Why 0x10? Is there a specific reason?
> +
> /// GSP runtime data.
> -///
> -/// This is an empty pinned placeholder for now.
> #[pin_data]
> -pub(crate) struct Gsp {}
> +pub(crate) struct Gsp {
> + libos: CoherentAllocation<LibosMemoryRegionInitArgument>,
> + pub loginit: CoherentAllocation<u8>,
> + pub logintr: CoherentAllocation<u8>,
> + pub logrm: CoherentAllocation<u8>,
This creates warnings for older compiler version, please use pub(crate) instead.
> +}
> +
> +#[repr(C)]
> +struct PteArray<const NUM_ENTRIES: usize>([u64; NUM_ENTRIES]);
> +/// SAFETY: arrays of `u64` implement `AsBytes` and we are but a wrapper
> around it.
> +unsafe impl<const NUM_ENTRIES: usize> AsBytes for PteArray<NUM_ENTRIES> {}
Please separate struct definitions and impl blocks with an empty line.
> +impl<const NUM_PAGES: usize> PteArray<NUM_PAGES> {
> + fn new(handle: DmaAddress) -> Self {
No check that NUM_PAGES actually fits the size of the DMA buffer handle passed
in? What happens if they do not match?
> + let mut ptes = [0u64; NUM_PAGES];
> + for (i, pte) in ptes.iter_mut().enumerate() {
> + *pte = handle + ((i as u64) << GSP_PAGE_SHIFT);
I think this should be handle.checked_add(). Additionally we should add the
following compile time check to make sure that the shift can never overflow:
const _MAX_OFFSET: usize = NUM_PAGES << GSP_PAGE_SHIFT;
> + }
> +
> + Self(ptes)
> + }
> +}
> +
> +/// Creates a new `CoherentAllocation<A>` with `name` of `size` elements, and
> +/// register it into the `libos` object at argument position `libos_arg_nr`.
> +fn create_logbuffer_dma_object(
> + dev: &device::Device<device::Bound>,
> +) -> Result<CoherentAllocation<u8>> {
> + let mut obj = CoherentAllocation::<u8>::alloc_coherent(
> + dev,
> + RM_LOG_BUFFER_NUM_PAGES * GSP_PAGE_SIZE,
> + GFP_KERNEL | __GFP_ZERO,
> + )?;
> + let ptes = PteArray::<RM_LOG_BUFFER_NUM_PAGES>::new(obj.dma_handle());
> +
> + // SAFETY: `obj` has just been created and we are its sole user.
> + unsafe {
> + // Copy the self-mapping PTE at the expected location.
> + obj.as_slice_mut(size_of::<u64>(), size_of_val(&ptes))?
> + .copy_from_slice(ptes.as_bytes())
> + };
> +
> + Ok(obj)
> +}
I think we should just create a new gsp::Logbuffer type for this rather than
have a function as object constructor.
>
> impl Gsp {
> - pub(crate) fn new() -> impl PinInit<Self> {
> - pin_init!(Self {})
> + pub(crate) fn new(pdev: &pci::Device<device::Bound>) -> Result<impl
> PinInit<Self, Error>> {
> + let dev = pdev.as_ref();
> + let libos =
> CoherentAllocation::<LibosMemoryRegionInitArgument>::alloc_coherent(
> + dev,
> + GSP_PAGE_SIZE / size_of::<LibosMemoryRegionInitArgument>(),
> + GFP_KERNEL | __GFP_ZERO,
> + )?;
> + let loginit = create_logbuffer_dma_object(dev)?;
> + dma_write!(libos[0] = LibosMemoryRegionInitArgument::new("LOGINIT",
> &loginit))?;
> + let logintr = create_logbuffer_dma_object(dev)?;
> + dma_write!(libos[1] = LibosMemoryRegionInitArgument::new("LOGINTR",
> &logintr))?;
> + let logrm = create_logbuffer_dma_object(dev)?;
> + dma_write!(libos[2] = LibosMemoryRegionInitArgument::new("LOGRM",
> &logrm))?;
> +
> + Ok(try_pin_init!(Self {
> + libos,
> + loginit,
> + logintr,
> + logrm,
> + }))
> }
> }
> diff --git a/drivers/gpu/nova-core/gsp/fw.rs b/drivers/gpu/nova-core/gsp/fw.rs
> index 181baa401770..dd1e7fc85d85 100644
> --- a/drivers/gpu/nova-core/gsp/fw.rs
> +++ b/drivers/gpu/nova-core/gsp/fw.rs
> @@ -7,8 +7,10 @@
>
> use core::ops::Range;
>
> +use kernel::dma::CoherentAllocation;
> use kernel::ptr::Alignable;
> use kernel::sizes::SZ_1M;
> +use kernel::transmute::{AsBytes, FromBytes};
>
> use crate::gpu::Chipset;
> use crate::gsp;
> @@ -99,3 +101,40 @@ pub(crate) fn wpr_heap_size(&self, chipset: Chipset,
> fb_size: u64) -> u64 {
> /// addresses of the GSP bootloader and firmware.
> #[repr(transparent)]
> pub(crate) struct GspFwWprMeta(bindings::GspFwWprMeta);
> +
> +#[repr(transparent)]
> +pub(crate) struct
> LibosMemoryRegionInitArgument(bindings::LibosMemoryRegionInitArgument);
Please add some documentation for the type.
> +
> +// SAFETY: Padding is explicit and will not contain uninitialized data.
> +unsafe impl AsBytes for LibosMemoryRegionInitArgument {}
> +
> +// SAFETY: This struct only contains integer types for which all bit patterns
> +// are valid.
> +unsafe impl FromBytes for LibosMemoryRegionInitArgument {}
> +
> +impl LibosMemoryRegionInitArgument {
> + pub(crate) fn new<A: AsBytes + FromBytes>(
> + name: &'static str,
> + obj: &CoherentAllocation<A>,
> + ) -> Self {
> + /// Generates the `ID8` identifier required for some GSP objects.
> + fn id8(name: &str) -> u64 {
> + let mut bytes = [0u8; core::mem::size_of::<u64>()];
> +
> + for (c, b) in name.bytes().rev().zip(&mut bytes) {
> + *b = c;
> + }
> +
> + u64::from_ne_bytes(bytes)
> + }
> +
> + Self(bindings::LibosMemoryRegionInitArgument {
> + id8: id8(name),
> + pa: obj.dma_handle(),
> + size: obj.size() as u64,
> + kind:
> bindings::LibosMemoryRegionKind_LIBOS_MEMORY_REGION_CONTIGUOUS as u8,
> + loc:
> bindings::LibosMemoryRegionLoc_LIBOS_MEMORY_REGION_LOC_SYSMEM as u8,
Please prefer into() if possible.
