[PATCH 07/14] rust: pci: add num_vf(), to return number of VFs

[Zhi Wang <zhiw@nvidia.com>]

From: Peter Colberg <pcolberg@redhat.com>

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

zhiw: Keep this helper private to the PCI SR-IOV implementation instead
of extending the public `Device` API. Add a dead-code expectation
because this standalone API commit has no in-tree caller.

Signed-off-by: Peter Colberg <pcolberg@redhat.com>
Signed-off-by: Zhi Wang <zhiw@nvidia.com>
---
 rust/kernel/pci.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index ed42511911d7..f2d71daef83a 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -523,6 +523,14 @@ pub(crate) fn is_virtfn(&self) -> bool {
         unsafe { (*self.as_raw()).is_virtfn() != 0 }
     }
 
+    /// Returns the number of Virtual Functions (VF) enabled for a Physical Function (PF).
+    #[cfg(CONFIG_PCI_IOV)]
+    #[expect(dead_code)]
+    pub(crate) fn num_vf(&self) -> i32 {
+        // SAFETY: `self.as_raw` is a valid pointer to a `struct pci_dev`.
+        unsafe { bindings::pci_num_vf(self.as_raw()) }
+    }
+
     /// Returns the size of the given PCI BAR resource.
     pub fn resource_len(&self, bar: u32) -> Result<bindings::resource_size_t> {
         if !Bar::index_is_valid(bar) {