Re: [PATCH v3 2/8] rust: pci: add sriov_get_totalvfs() helper

On Wed Jul 8, 2026 at 11:03 PM JST, Alexandre Courbot wrote:
> On Wed Jul 1, 2026 at 3:26 PM JST, Zhi Wang wrote:
>> Expose pci_sriov_get_totalvfs() to Rust PCI drivers so they can query
>> how many SR-IOV VFs a device supports.
>>
>> Cc: Alexandre Courbot <[email protected]>
>> Cc: Bjorn Helgaas <[email protected]>
>> Cc: David Laight <[email protected]>
>> Cc: Gary Guo <[email protected]>
>> Cc: [email protected]
>> Link: https://lore.kernel.org/all/[email protected]/
>> Signed-off-by: Zhi Wang <[email protected]>
>> ---
>>  rust/kernel/pci.rs | 11 +++++++++++
>>  1 file changed, 11 insertions(+)
>>
>> diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
>> index 5071cae6543f..21c51981c02e 100644
>> --- a/rust/kernel/pci.rs
>> +++ b/rust/kernel/pci.rs
>> @@ -450,6 +450,17 @@ pub fn pci_class(&self) -> Class {
>>          // SAFETY: `self.as_raw` is a valid pointer to a `struct pci_dev`.
>>          Class::from_raw(unsafe { (*self.as_raw()).class })
>>      }
>> +
>> +    /// Returns the total number of VFs, or 0 if SR-IOV is not available.
>> +    #[inline]
>> +    pub fn sriov_get_totalvfs(&self) -> u16 {
>> +        // SAFETY: `self.as_raw()` is a valid pointer to a `struct pci_dev`.
>> +        let total_vfs = unsafe { bindings::pci_sriov_get_totalvfs(self.as_raw()) };
>> +
>> +        // CAST: The C helper returns `unsigned int`, but the value originates
>> +        // from TotalVFs/driver_max_VFs, so this cast cannot truncate.
>
> nit: "from TotalVFs/driver_max_VFs (which are defined as `u16`), ..."
>
> With that,
>
> Reviewed-by: Alexandre Courbot <[email protected]>

Sorry, need to take my tag back. :( Build is failing if `CONFIG_PCI_IOV`
is not set:

    error[E0425]: cannot find function `pci_sriov_get_totalvfs` in crate `bindings`
      --> ../rust/kernel/pci.rs:458:44
        |
    458 |         let total_vfs = unsafe { bindings::pci_sriov_get_totalvfs(self.as_raw()) };
        |                                            ^^^^^^^^^^^^^^^^^^^^^^ not found in `bindings`

Looks like you need to add a helper in `rust/helpers/pci.c` as the
inline C function used when `CONFIG_PCI_IOV` is not set can not be
invoked by Rust.