Re: [PATCH v4 19/20] gpu: nova-core: extract FWSEC from BIOS and patch it to run FWSEC-FRTS

[Danilo Krummrich <dakr@kernel.org>]

On Wed, May 21, 2025 at 03:45:14PM +0900, Alexandre Courbot wrote:
> +impl FirmwareDmaObject<FwsecFirmware> {
> +    /// Patch the Fwsec firmware image in `fw` to run the command `cmd`.
> +    fn patch_command(&mut self, v3_desc: &FalconUCodeDescV3, cmd: FwsecCommand) -> Result<()> {

Same comment as on the previous patch regarding patch_signature().

<snip>

> +    fn dmem_load_params(&self) -> FalconLoadTarget {
> +        FalconLoadTarget {
> +            src_start: self.desc.imem_load_size,
> +            dst_start: self.desc.dmem_phys_base,
> +            len: Layout::from_size_align(self.desc.dmem_load_size as usize, 256)
> +                // Cannot panic, as 256 is non-zero and a power of 2.
> +                .unwrap()

There is also Layout::from_size_align_unchecked(), which I prefer over unwrap().
I think we should never use unwrap() and rather the unsafe variant, which at least
forces us to document things properly, if there's no other option.

In this case, however, I don't see why we can't just propage the error? This
method is used from Falcon::dma_load(), which returns a Result anyways, so let's
just propagate it.

In general, we should *never* potentially panic the whole kernel just because
of a wrong size calculation in a driver.