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Date: Tue, 17 Feb 2026 21:10:36 +0100
Message-Id: <DGHIDF706REU.3PF025P56DMS2@kernel.org>
Subject: Re: [PATCH v4 27/33] gpu: nova-core: Hopper/Blackwell: larger WPR2
 (GSP) heap
Cc: "Alexandre Courbot" <acourbot@nvidia.com>, "Joel Fernandes"
 <joelagnelf@nvidia.com>, "Timur Tabi" <ttabi@nvidia.com>, "Alistair Popple"
 <apopple@nvidia.com>, "Eliot Courtney" <ecourtney@nvidia.com>, "Zhi Wang"
 <zhiw@nvidia.com>, "David Airlie" <airlied@gmail.com>, "Simona Vetter"
 <simona@ffwll.ch>, "Bjorn Helgaas" <bhelgaas@google.com>, "Miguel Ojeda"
 <ojeda@kernel.org>, "Alex Gaynor" <alex.gaynor@gmail.com>, "Boqun Feng"
 <boqun.feng@gmail.com>, "Gary Guo" <gary@garyguo.net>,
 =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>, "Benno Lossin"
 <lossin@kernel.org>, "Andreas Hindborg" <a.hindborg@kernel.org>, "Alice
 Ryhl" <aliceryhl@google.com>, "Trevor Gross" <tmgross@umich.edu>,
 <nouveau@lists.freedesktop.org>, <rust-for-linux@vger.kernel.org>, "LKML"
 <linux-kernel@vger.kernel.org>
To: "John Hubbard" <jhubbard@nvidia.com>
From: "Danilo Krummrich" <dakr@kernel.org>
References: <20260210024601.593248-1-jhubbard@nvidia.com>
 <20260210024601.593248-28-jhubbard@nvidia.com>
In-Reply-To: <20260210024601.593248-28-jhubbard@nvidia.com>

On Tue Feb 10, 2026 at 3:45 AM CET, John Hubbard wrote:
> @@ -74,7 +94,7 @@ fn management_overhead(fb_size: u64) -> u64 {
>          u64::from(bindings::GSP_FW_HEAP_PARAM_SIZE_PER_GB_FB)
>              .saturating_mul(fb_size_gb)
>              .align_up(GSP_HEAP_ALIGNMENT)
> -            .unwrap_or(u64::MAX)
> +            .expect("management_overhead alignment overflow")

Ultimately, the relevant value for this calculation (fb_size) comes from th=
e
hardware through a register read if I'm not mistaken, we shouldn't panic on
that, but rather handle is as an error if the read value is not plausible.