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

[Peter Colberg <pcolberg@redhat.com>]

On Sun, Dec 07, 2025 at 01:33:55AM -0500, Joel Fernandes wrote:
> 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(())
> 
> nit: Why not use `to_result()` here?

Thanks! I queued `to_result()` for v2, from an unrelated review [1].

Peter

[1] https://lore.kernel.org/rust-for-linux/b8234f181d35b21a3319b95a54b21bdba11b8001.camel@redhat.com/

> 
> thanks,
> 
>  - Joel
> 
> 
> 
> > +    }
> > +
> > +    /// 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()) };
> > +    }
> >  }
> >  
> >  // SAFETY: `pci::Device` is a transparent wrapper of `struct pci_dev`.
> > 
> > -- 
> > 2.51.1
> > 
>