From mboxrd@z Thu Jan  1 00:00:00 1970
From: Claude Code Review Bot <claude-review@example.com>
To: dri-devel-reviews@example.com
Subject:
 Claude review: gpu: nova-core: fix stack overflow in GSP memory allocation
Date: Fri, 13 Feb 2026 18:06:47 +1000
Message-ID: <review-patch1-20260212-drm-rust-next-v1-1-409398b12e61@proton.me>
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Patch Review

**rustfmt failure**: The kernel test robot already reported this. The indenta=
tion of the `.dma_handle()` chain in `cmdq.rs` does not match `rustfmt` expec=
tations:

> +        for i in 0..NUM_PAGES {
> +            let pte_value =3D gsp_mem
> +                    .dma_handle()
> +                    .checked_add(num::usize_as_u64(i) << GSP_PAGE_SHIFT)
> +                    .ok_or(EOVERFLOW)?;

The `.dma_handle()` has 20 spaces of indentation (double-indented) whereas `r=
ustfmt` wants 16 (single continuation indent). This needs to be fixed before =
the patch can be merged.

**Unused import**: The patch adds `use core::iter::Iterator` to `gsp.rs`, but=
 nothing in the file uses `Iterator` as a named type. The `Iterator` trait is=
 already in scope via the prelude. Was this perhaps left over from an earlier=
 iteration of the patch?

> +use core::iter::Iterator;

**Misleading constant name in cmdq.rs**: The locally-defined `NUM_PAGES` does=
n't represent a number of pages =E2=80=94 it's the number of PTE entries that=
 fit in one GSP page:

> +        const NUM_PAGES: usize =3D GSP_PAGE_SIZE / size_of::<u64>();

This evaluates to 512 (4096 / 8), which is the number of u64 entries, not pag=
es. The name was inherited from the old `PteArray` generic parameter, which a=
lso misnamed it. Something like `NUM_PTES` or `PTE_COUNT` would be clearer an=
d would match the existing `Cmdq::NUM_PTES` constant defined elsewhere in the=
 same file. Not a correctness issue, but worth cleaning up since the code is =
being rewritten anyway.

**Comment typo in gsp.rs**: There's a double space in the comment:

> +        // As in [`DmaGspMem`], this is a  one by one GSP Page write to th=
e memory

Minor nit =E2=80=94 "a  one" should be "a one".

**Inconsistent approaches between the two call sites**: In `gsp.rs`, the PTE =
writes are done through a byte slice obtained from `as_slice_mut`, writing `t=
o_ne_bytes()`. In `cmdq.rs`, the writes go through raw pointer arithmetic and=
 `field_write`. Both work, but the `gsp.rs` approach is simpler and doesn't r=
equire unsafe code beyond the initial `as_slice_mut` call. Is there a reason =
the `cmdq.rs` site couldn't use the same pattern? The `LogBuffer` allocates `=
CoherentAllocation<u8>` so it naturally uses byte-level access, while `GspMem=
` is a typed allocation =E2=80=94 but even so, the `field_write` approach see=
ms more complex than necessary for writing individual array elements.

**Correctness**: Setting aside the style concerns, the logic in both call sit=
es correctly reproduces the behavior of the removed `PteArray::new` =E2=80=94=
 computing `base_dma_addr + i * GSP_PAGE_SIZE` for each PTE entry and writing=
 it to the appropriate location in the DMA buffer. The overflow checking via =
`checked_add` is preserved. The error propagation with `?` on `ok_or(EOVERFLO=
W)` inside the loop correctly returns early if any PTE address overflows, mat=
ching the old behavior.

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