Re: [PATCH 3/8] rust: pci: add {enable,disable}_sriov(), to control SR-IOV capability

[Jason Gunthorpe <jgg@ziepe.ca>]

On Wed, Nov 19, 2025 at 05:19:07PM -0500, Peter Colberg wrote:
> Add methods to enable and disable the Single Root I/O Virtualization
> (SR-IOV) capability for a PCI device. The wrapped C methods take care
> of validating whether the device is a Physical Function (PF), whether
> SR-IOV is currently disabled (or enabled), and whether the number of
> requested VFs does not exceed the total number of supported VFs.
> 
> Suggested-by: Danilo Krummrich <dakr@kernel.org>
> Signed-off-by: Peter Colberg <pcolberg@redhat.com>
> ---
>  rust/kernel/pci.rs | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
> index 814990d386708fe2ac652ccaa674c10a6cf390cb..556a01ed9bc3b1300a3340a3d2383e08ceacbfe5 100644
> --- a/rust/kernel/pci.rs
> +++ b/rust/kernel/pci.rs
> @@ -454,6 +454,36 @@ pub fn set_master(&self) {
>          // SAFETY: `self.as_raw` is guaranteed to be a pointer to a valid `struct pci_dev`.
>          unsafe { bindings::pci_set_master(self.as_raw()) };
>      }
> +
> +    /// Enable the Single Root I/O Virtualization (SR-IOV) capability for this device,
> +    /// where `nr_virtfn` is number of Virtual Functions (VF) to enable.
> +    #[cfg(CONFIG_PCI_IOV)]
> +    pub fn enable_sriov(&self, nr_virtfn: i32) -> Result {
> +        // SAFETY:
> +        // `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.
> +        let ret = unsafe { bindings::pci_enable_sriov(self.as_raw(), nr_virtfn) };
> +        if ret != 0 {
> +            return Err(crate::error::Error::from_errno(ret));
> +        }
> +        Ok(())
> +    }
> +
> +    /// Disable the Single Root I/O Virtualization (SR-IOV) capability for this device.
> +    #[cfg(CONFIG_PCI_IOV)]
> +    pub fn disable_sriov(&self) {
> +        // SAFETY:
> +        // `self.as_raw` returns a valid pointer to a `struct pci_dev`.
> +        //
> +        // `pci_disable_sriov()` checks that the disable operation is valid:
> +        // - the device is a Physical Function (PF), and
> +        // - SR-IOV is currently enabled.
> +        unsafe { bindings::pci_disable_sriov(self.as_raw()) };
> +    }

Both these functions should only be called on bound devices - the
safety statement should call it out, does the code require it?

Also per my other email SRIOV should be disabled before a driver can
be unbound, this patch should take care of it to not introduce an
dangerous enable_sriov().

Jason