[PATCH v2 02/12] rust: pci: expose the VF index within its PF

[Simon Song <xinmengs@nvidia.com>]

From: Danilo Krummrich <dakr@kernel.org>

Nova identifies a vGPU instance by the VF's index within its PF. Expose
pci_iov_vf_id() through Device::vf_id() so a Rust VF driver can obtain
that index, with an error for devices that are not VFs.

Restrict vf_id() to Device<device::Bound>

Suggested-by: Danilo Krummrich <dakr@kernel.org>
Suggested-by: Zhi Wang <zhiw@nvidia.com>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Zhi Wang <zhiw@nvidia.com>
Signed-off-by: Simon Song <xinmengs@nvidia.com>
---
 rust/kernel/pci/iov.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/rust/kernel/pci/iov.rs b/rust/kernel/pci/iov.rs
index 9d9bd3ac702..76b2e395ca3 100644
--- a/rust/kernel/pci/iov.rs
+++ b/rust/kernel/pci/iov.rs
@@ -329,6 +329,14 @@ unsafe impl<F: ForLt> Send for VfRegistration<'_, F> where for<'a> F::Of<'a>: Se
 unsafe impl<F: ForLt> Sync for VfRegistration<'_, F> where for<'a> F::Of<'a>: Send + Sync {}
 
 impl Device<device::Bound> {
+    /// Return the zero-based VF index within its PF, or an error for a non-VF device.
+    pub fn vf_id(&self) -> Result<u32> {
+        // SAFETY: `self.as_raw()` points to a live PCI device; the helper checks VF membership.
+        let id = unsafe { bindings::pci_iov_vf_id(self.as_raw()) };
+        to_result(id)?;
+        Ok(id as u32)
+    }
+
     /// Internal helper: reads the `vf_registration_data_rust` pointer from the
     /// PF, checks the `TypeId`, and returns a pinned reference.
     ///
-- 
2.43.7