Re: [PATCH v2 1/8] rust: pci: add {enable,disable}_sriov(), to control SR-IOV capability

[Zhi Wang <zhiw@nvidia.com>]

On Fri, 25 Sep 2026 16:43:16 -0400
Peter Colberg <peter@colberg.org> wrote:

> Hi Zhi,
> 
> On Thu, Sep 24, 2026 at 10:05:48PM +0300, Zhi Wang wrote:
> > From: Peter Colberg <pcolberg@redhat.com>  
> 
> Thank you for updating the series and apologies for the silence.
> 
> As part of the next revision, could you please update my email address
> in all patches, which has changed (for kernel contributions only):
> 
> From: Peter Colberg <peter@colberg.org>
> 

Sure!

> Thanks,
> Peter
> 
> > 
> > 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.
> > 
> > Synchronously disable SR-IOV in the Rust PCI remove callback before
> > unbinding the PF driver. This ensures that when a Virtual
> > Function (VF) is bound to a driver, the corresponding Physical
> > Function (PF) is bound to a driver, too, which is a prerequisite
> > for exposing a safe Rust API that allows a VF driver to obtain the
> > PF device for a VF device and subsequently access the private data
> > of the PF driver.
> > 
> > Suggested-by: Danilo Krummrich <dakr@kernel.org>
> > Signed-off-by: Peter Colberg <pcolberg@redhat.com>
> > Signed-off-by: Zhi Wang <zhiw@nvidia.com>
> > ---
> >  rust/kernel/pci.rs | 36 ++++++++++++++++++++++++++++++++++++
> >  1 file changed, 36 insertions(+)
> > 
> > diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
> > index 3ec897709e89..e6dac919f02d 100644
> > --- a/rust/kernel/pci.rs
> > +++ b/rust/kernel/pci.rs
> > @@ -133,6 +133,10 @@ extern "C" fn remove_callback(pdev: *mut
> > bindings::pci_dev) { // INVARIANT: `pdev` is valid for the duration
> > of `remove_callback()`. let pdev = unsafe {
> > &*pdev.cast::<Device<device::CoreInternal<'_>>>() }; 
> > +        // Keep PF data installed until all VF remove callbacks
> > have completed.
> > +        #[cfg(CONFIG_PCI_IOV)]
> > +        pdev.disable_sriov();
> > +
> >          // SAFETY: `remove_callback` is only ever called after a
> > successful call to // `probe_callback`, hence it's guaranteed that
> > `Device::set_drvdata()` has been called // and stored a
> > `Pin<KBox<T::Data<'_>>>`. @@ -472,6 +476,38 @@ 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.
> > +        //
> > +        // The Core device context inherits from the Bound device
> > context,
> > +        // which guarantees that the PF device is bound to a
> > driver.
> > +        to_result(unsafe {
> > bindings::pci_enable_sriov(self.as_raw(), nr_virtfn) })
> > +    }
> > +
> > +    /// 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.
> > +        //
> > +        // The Core device context inherits from the Bound device
> > context,
> > +        // which guarantees that the PF device is bound to a
> > driver.
> > +        unsafe { bindings::pci_disable_sriov(self.as_raw()) };
> > +    }
> >  }
> >  
> >  // SAFETY: `pci::Device` is a transparent wrapper of `struct
> > pci_dev`. -- 
> > 2.53.0
> >