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Date: Wed, 4 Jun 2025 12:42:09 +0200
From: Danilo Krummrich <dakr@kernel.org>
To: Alexandre Courbot <acourbot@nvidia.com>
Cc: Miguel Ojeda <ojeda@kernel.org>, Alex Gaynor <alex.gaynor@gmail.com>,
	Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
	=?iso-8859-1?Q?Bj=F6rn?= Roy Baron <bjorn3_gh@protonmail.com>,
	Benno Lossin <benno.lossin@proton.me>,
	Andreas Hindborg <a.hindborg@kernel.org>,
	Alice Ryhl <aliceryhl@google.com>, Trevor Gross <tmgross@umich.edu>,
	David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	John Hubbard <jhubbard@nvidia.com>, Ben Skeggs <bskeggs@nvidia.com>,
	Joel Fernandes <joelagnelf@nvidia.com>,
	Timur Tabi <ttabi@nvidia.com>, Alistair Popple <apopple@nvidia.com>,
	linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org,
	nouveau@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v4 19/20] gpu: nova-core: extract FWSEC from BIOS and
 patch it to run FWSEC-FRTS
Message-ID: <aEAjASkf9t4s4RsY@cassiopeiae>
References: <20250521-nova-frts-v4-0-05dfd4f39479@nvidia.com>
 <20250521-nova-frts-v4-19-05dfd4f39479@nvidia.com>
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In-Reply-To: <20250521-nova-frts-v4-19-05dfd4f39479@nvidia.com>

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.