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

[Peter Colberg]

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@xxxxxxxxxx>
Signed-off-by: Peter Colberg <pcolberg@xxxxxxxxxx>
---
 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()) };
+    }
 }
 
 // SAFETY: `pci::Device` is a transparent wrapper of `struct pci_dev`.

-- 
2.51.1