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Date: Wed, 30 Sep 2026 12:58:27 +0200
Message-Id: <DLSLJ8WO3LRO.3PBCCWG3GK6YH@kernel.org>
From: "Danilo Krummrich" <dakr@kernel.org>
Subject: Re: [PATCH v3 01/10] rust: pci: add internal SR-IOV enable and
 disable helpers
Cc: <rust-for-linux@vger.kernel.org>, <linux-pci@vger.kernel.org>,
 <linux-kernel@vger.kernel.org>, <aliceryhl@google.com>,
 <bhelgaas@google.com>, <kwilczynski@kernel.org>, <ojeda@kernel.org>,
 <boqun@kernel.org>, <gary@garyguo.net>, <bjorn3_gh@protonmail.com>,
 <lossin@kernel.org>, <a.hindborg@kernel.org>, <tmgross@umich.edu>,
 <markus.probst@posteo.de>, <cjia@nvidia.com>, <smitra@nvidia.com>,
 <ankita@nvidia.com>, <aniketa@nvidia.com>, <kwankhede@nvidia.com>,
 <targupta@nvidia.com>, <kjaju@nvidia.com>, <alkumar@nvidia.com>,
 <acourbot@nvidia.com>, <jhubbard@nvidia.com>, <zhiwang@kernel.org>,
 <jgg@nvidia.com>, <alex@shazbot.org>, "Peter Colberg" <peter@colberg.org>
To: "Zhi Wang" <zhiw@nvidia.com>
References: <cover.1790705494.git.zhiw@nvidia.com>
 <af34ce6151b5be98668d712fbe62b5d6af291770.1790759932.git.zhiw@nvidia.com>
In-Reply-To: <af34ce6151b5be98668d712fbe62b5d6af291770.1790759932.git.zhiw@nvidia.com>

On Wed Sep 30, 2026 at 12:18 PM CEST, Zhi Wang wrote:
> +impl Device<device::CoreInternal<'_>> {
> +    /// Enable the Single Root I/O Virtualization (SR-IOV) capability fo=
r this device,
> +    /// where `nr_virtfn` is number of Virtual Functions (VF) to enable.
> +    #[expect(dead_code)]
> +    pub(crate) fn enable_sriov(&self, nr_virtfn: c_int) -> Result {

This can just be a u16; there are no implicit type conversions in Rust and =
the
PCIe SR-IOV spec defines this as 16bit register.

The conversion should be infallible, so you can just pass nr_virtfn.into().

> +        // SAFETY:
> +        // `self.as_raw` returns a valid pointer to a `struct pci_dev`.
> +        //
> +        // `pci_enable_sriov()` checks that the enable operation is vali=
d:
> +        // - the device is a Physical Function (PF),
> +        // - SR-IOV is currently disabled, and
> +        // - `nr_virtfn` does not exceed the total number of supported V=
Fs.
> +        //
> +        // The CoreInternal device context inherits from the Bound devic=
e context,
> +        // which guarantees that the PF device is bound to a driver.

	// - `self.as_raw` returns a valid pointer to a `struct pci_dev`.
	//
	// - `pci_enable_sriov()` checks that the enable operation is valid:
	//   - the device is a Physical Function (PF),
	//   - SR-IOV is currently disabled, and
	//   - `nr_virtfn` does not exceed the total number of supported VFs.
	//
	// - The [`CoreInternal`] device context inherits from the [`Bound`] devic=
e context,
	//   which guarantees that the PF device is bound to a driver.

> +        to_result(unsafe { bindings::pci_enable_sriov(self.as_raw(), nr_=
virtfn) })
> +    }