IFLA_NUM_VF not set or improperly parsed

[Thomas Graf]

On 02/13/14 at 04:20pm, Jef Oliver wrote:
> Hello,
> 
> On a system with SRIOV support and functional VFs (ixgbe) loaded (2
> per port), I get -NLE_OPNOTSUPP when calling rtnl_link_get_num_vf on
> any link with SRIOV support and VFs loaded. I am able to list the
> VFs with ip link show. I was digging through the code and got as far
> as IFLA_NUM_VF being parsed in the returned packet. This gets a bit
> deeper than my current netlink knowledge, so I am unsure where to
> move to next.
> 
> I have reproduced this in RHEL 6.4/6.5 with stock 2.6.32 inbox and
> updated 2.6.32 kernels, RHEL 6.5 with upstream 3.11.x and 3.12.x, as
> well as on an Arch Linux system running 3.12.x.
> 
> I am perfectly willing to dig deeper and figure out what is going on
> with a bit of guidance, or assist in any way I can.

The issue is that libnl does not yet provide the IFLA_EXT_MASK
attribute with a value of RTEXT_FILTER_VF when sending RTM_GETLINK
which is required to trigger sending of VF information in the kernel.

rtnl_link_build_get_request() must be extended with something
like:

        NLA_PUT_U32(msg, IFLA_EXT_MASK, RTEXT_FILTER_VF);