[PATCH v5 4/9] rust: pci: add num_vf(), to return number of VFs

[Simon Song <xinmengs@nvidia.com>]

From: Peter Colberg <peter@colberg.org>

Add a method to return the number of Virtual Functions (VF) enabled for
a Physical Function (PF).

Expose the query in the PCI core callback context and return u16,
matching the type of the VF count stored by the PCI core.

Signed-off-by: Peter Colberg <peter@colberg.org>
Signed-off-by: Zhi Wang <zhiw@nvidia.com>
Signed-off-by: Simon Song <xinmengs@nvidia.com>
---
 rust/kernel/pci/iov.rs | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/rust/kernel/pci/iov.rs b/rust/kernel/pci/iov.rs
index 6f8f95ed618..1ff0ce94f16 100644
--- a/rust/kernel/pci/iov.rs
+++ b/rust/kernel/pci/iov.rs
@@ -11,6 +11,17 @@
     prelude::*, //
 };
 
+impl Device<device::Core<'_>> {
+    /// Returns the number of Virtual Functions (VF) enabled for a Physical Function (PF).
+    #[inline]
+    pub fn num_vf(&self) -> u16 {
+        // SAFETY: `self.as_raw()` is valid and this call runs in the PCI core callback context.
+        unsafe { bindings::pci_num_vf(self.as_raw()) }
+            .try_into()
+            .expect("pdev->sriov->num_VFs is u16")
+    }
+}
+
 impl Device<device::CoreInternal<'_>> {
     /// Enable the Single Root I/O Virtualization (SR-IOV) capability for this device,
     /// where `nr_virtfn` is number of Virtual Functions (VF) to enable.
-- 
2.43.7