On Wed, May 07, 2025 at 10:52:37PM +0900, Alexandre Courbot wrote:
> Since we will need to allocate lots of distinct memory chunks to be
> shared between GPU and CPU, introduce a type dedicated to that. It is a
> light wrapper around CoherentAllocation.
>
> Signed-off-by: Alexandre Courbot <acour...@nvidia.com>
> ---
> drivers/gpu/nova-core/dma.rs | 60
> ++++++++++++++++++++++++++++++++++++++
> drivers/gpu/nova-core/nova_core.rs | 1 +
> 2 files changed, 61 insertions(+)
>
> diff --git a/drivers/gpu/nova-core/dma.rs b/drivers/gpu/nova-core/dma.rs
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..9d90ae01d0044eaab4ddbc3eba216741d7a623ef
> --- /dev/null
> +++ b/drivers/gpu/nova-core/dma.rs
> @@ -0,0 +1,60 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +//! Simple DMA object wrapper.
> +
> +// To be removed when all code is used.
> +#![expect(dead_code)]
> +
> +use core::ops::{Deref, DerefMut};
> +
> +use kernel::device;
> +use kernel::dma::CoherentAllocation;
> +use kernel::page::PAGE_SIZE;
> +use kernel::prelude::*;
> +
> +pub(crate) struct DmaObject {
> + dma: CoherentAllocation<u8>,
> +}
> +
> +impl DmaObject {
> + pub(crate) fn new(dev: &device::Device<device::Bound>, len: usize) ->
> Result<Self> {
> + let len = core::alloc::Layout::from_size_align(len, PAGE_SIZE)
> + .map_err(|_| EINVAL)?
> + .pad_to_align()
> + .size();
> + let dma = CoherentAllocation::alloc_coherent(dev, len, GFP_KERNEL |
> __GFP_ZERO)?;
> +
> + Ok(Self { dma })
> + }
> +
> + pub(crate) fn from_data(dev: &device::Device<device::Bound>, data:
> &[u8]) -> Result<Self> {
> + Self::new(dev, data.len()).map(|mut dma_obj| {
> + // SAFETY:
> + // - The copied data fits within the size of the allocated
> object.
> + // - We have just created this object and there is no other user
> at this stage.
> + unsafe {
> + core::ptr::copy_nonoverlapping(
> + data.as_ptr(),
> + dma_obj.dma.start_ptr_mut(),
> + data.len(),
> + );
> + }
This will be replaced with CoherentAllocation::write() I suppose? Please add a
corresponding TODO.
