On Thu Mar 26, 2026 at 5:43 AM GMT, Alexandre Courbot wrote:
> `driver_read_area` and `driver_write_area` are internal methods that
> return slices containing the area of the command queue buffer that the
> driver has exclusive read or write access, respectively.
>
> While their returned value is correct and safe to use, internally they
> temporarily create a reference to the whole command-buffer slice,
> including GSP-owned regions. These regions can change without notice,
> and thus creating a slice to them, even if never accessed, is undefined
> behavior.
>
> Fix this by rewriting these methods to use pointer projections in order
> to create slices to valid regions only. It should eventually be replaced
> by `IoView` and `IoSlice` once they land.
>
> Fixes: 75f6b1de8133 ("gpu: nova-core: gsp: Add GSP command queue bindings and
> handling")
> Reported-by: Danilo Krummrich <[email protected]>
> Closes: https://lore.kernel.org/all/[email protected]/
> Signed-off-by: Alexandre Courbot <[email protected]>
Reviewed-by: Gary Guo <[email protected]>
> ---
> Changes in v3:
> - Rebase on top of latest `drm-rust-next` (with `Coherent` patches).
> - Use pointer projections. (thanks Gary!)
> - Link to v2:
> https://patch.msgid.link/[email protected]
>
> Changes in v2:
> - Use `u32_as_usize` consistently.
> - Reduce the number of `unsafe` blocks by computing the end offset of
> the returned slices and creating them at the end, in one step.
> - Take advantage of the fact that both slices have the same start index
> regardless of the branch chosen.
> - Improve safety comments.
> - Link to v1:
> https://patch.msgid.link/[email protected]
> ---
> drivers/gpu/nova-core/gsp/cmdq.rs | 104
> ++++++++++++++++++++------------------
> 1 file changed, 55 insertions(+), 49 deletions(-)
