[PATCH v3 05/10] rust: pci: add bus callback sriov_configure(), to control SR-IOV from sysfs

Peter Colberg
2026-03-03T21:15:45Z

Add an optional bus callback sriov_configure() to pci::Driver trait,
using the vtable attribute to query if the driver implements the
callback. The callback is invoked when a user-space application
writes the number of VFs to the sysfs file `sriov_numvfs` to
enable SR-IOV, or zero to disable SR-IOV for a PCI device.

Suggested-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Peter Colberg <pcolberg@redhat.com>
---
rust/kernel/pci.rs | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 56 insertions(+)

diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index a4c27c674bd8bdf5e3316789d38d566e90b93fe2..88bd114970431bf8c3edef94c1d48567d895eaf6 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -83,6 +83,10 @@ unsafe fn register(
(*pdrv.get()).remove = Some(Self::remove_callback);
(*pdrv.get()).id_table = T::ID_TABLE.as_ptr();
(*pdrv.get()).managed_sriov = true;
+ #[cfg(CONFIG_PCI_IOV)]
+ if T::HAS_SRIOV_CONFIGURE {
+ (*pdrv.get()).sriov_configure = Some(Self::sriov_configure_callback);
+ }
}

// SAFETY: `pdrv` is guaranteed to be a valid `DriverType`.
@@ -135,6 +139,20 @@ extern "C" fn remove_callback(pdev: *mut bindings::pci_dev) {

T::unbind(pdev, data);
}
+
+ #[cfg(CONFIG_PCI_IOV)]
+ extern "C" fn sriov_configure_callback(
+ pdev: *mut bindings::pci_dev,
+ nr_virtfn: c_int,
+ ) -> c_int {
+ // SAFETY: The PCI bus only ever calls the sriov_configure callback with a valid pointer to
+ // a `struct pci_dev`.
+ //
+ // INVARIANT: `pdev` is valid for the duration of `sriov_configure_callback()`.
+ let pdev = unsafe { &*pdev.cast::<Device<device::CoreInternal>>() };
+
+ from_result(|| T::sriov_configure(pdev, nr_virtfn))
+ }
}

/// Declares a kernel module that exposes a single PCI driver.
@@ -325,6 +343,44 @@ pub trait Driver: Send {
fn unbind(dev: &Device<device::Core>, this: Pin<&Self>) {
let _ = (dev, this);
}
+
+ /// Single Root I/O Virtualization (SR-IOV) configure.
+ ///
+ /// Called when a user-space application enables or disables the SR-IOV capability for a
+ /// [`Device`] by writing the number of Virtual Functions (VF), `nr_virtfn` or zero to the
+ /// sysfs file `sriov_numvfs` for this device. Implementing this callback is optional.
+ ///
+ /// Further, and unlike for a PCI driver written in C, when a PF device with enabled VFs is
+ /// unbound from its bound [`Driver`], the `sriov_configure()` callback is invoked to disable
+ /// SR-IOV before the `unbind()` callback. This guarantees that when a VF device is bound to a
+ /// driver, the underlying PF device is bound to a driver, too.
+ ///
+ /// Upon success, this callback must return the number of VFs that were enabled, or zero if
+ /// SR-IOV was disabled.
+ ///
+ /// See [PCI Express I/O Virtualization].
+ ///
+ /// [PCI Express I/O Virtualization]: https://docs.kernel.org/PCI/pci-iov-howto.html
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// # use kernel::{device::Core, pci, prelude::*};
+ /// #[cfg(CONFIG_PCI_IOV)]
+ /// fn sriov_configure(dev: &pci::Device<Core>, nr_virtfn: i32) -> Result<i32> {
+ /// if nr_virtfn == 0 {
+ /// dev.disable_sriov();
+ /// } else {
+ /// dev.enable_sriov(nr_virtfn)?;
+ /// }
+ /// Ok(nr_virtfn)
+ /// }
+ /// ```
+ #[cfg(CONFIG_PCI_IOV)]
+ fn sriov_configure(dev: &Device<device::Core>, nr_virtfn: i32) -> Result<i32> {
+ let _ = (dev, nr_virtfn);
+ build_error!(crate::error::VTABLE_DEFAULT_ERROR)
+ }
}

/// The PCI device representation.

--
2.53.0