[Oisf-devel] Best userspace programming API for XDP features query to kernel?

[Peter Manev]

> On 5 Apr 2018, at 09:47, Victor Julien <lists at inliniac.net> wrote:
> 
>> On 04-04-18 14:28, Jesper Dangaard Brouer wrote:
>> Hi Suricata people,
>> 
>> When Eric Leblond (and I helped) integrated XDP in Suricata, we ran
>> into the issue, that at Suricata load/start time, we cannot determine
>> if the chosen XDP config options, like xdp-cpu-redirect[1], is valid on
>> this HW (e.g require driver XDP_REDIRECT support and bpf cpumap).
>> 
>> We would have liked a way to report that suricata.yaml config was
>> invalid for this hardware/setup.  Now, it just loads, and packets gets
>> silently dropped by XDP (well a WARN_ONCE and catchable via tracepoints).
>> 
>> My question to suricata developers: (Q1) Do you already have code that
>> query the kernel or drivers for features?
>> 
>> 
>> At the IOvisor call (2 weeks ago), we discussed two options of exposing
>> XDP features avail in a given driver.
>> 
>> Option#1: Extend existing ethtool -k/-K "offload and other features"
>> with some XDP features, that userspace can query. (Do you already query
>> offloads, regarding Q1)
> 
> I think if it would use the ioctl ETHTOOL interface it'd be easiest for
> us, as we already have code for this in place to check for offloading
> settings. See [1].
> 
> 
>> Option#2: Invent a new 'ip link set xdp' netlink msg with a query option.
> 
> Do you have an example of how this is queried?
> 
> 
>> (Q2) Do Suricata devs have any preference (or other options/ideas) for
>> the way the kernel expose this info to userspace?
> 
> Right now I think extending the ethtool logic is best for us.
> 

+1
I would prefer that approach too.


> 
> [1] https://github.com/OISF/suricata/blob/master/src/util-ioctl.c#L326
> 
> -- 
> ---------------------------------------------
> Victor Julien
> http://www.inliniac.net/
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>