netdev - Offloaded u32 classifier tables WAS (Re: [PATCH net 00/13] cls

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Date:   Mon, 10 Sep 2018 08:25:45 -0400
From:   Jamal Hadi Salim <jhs@...atatu.com>
To:     Al Viro <viro@...IV.linux.org.uk>
Cc:     netdev@...r.kernel.org, Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Rahul Lakkireddy <rahul.lakkireddy@...lsio.com>,
        Kumar A S <kumaras@...lsio.com>,
        Sridhar Samudrala <sridhar.samudrala@...el.com>,
        Alexander Duyck <alexander.h.duyck@...el.com>,
        Amritha Nambiar <amritha.nambiar@...el.com>,
        Jose.Abreu@...opsys.com, peppe.cavallaro@...com,
        alexandre.torgue@...com,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        Anjali Singhai Jain <anjali.singhai@...el.com>
Subject: Offloaded u32 classifier tables WAS (Re: [PATCH net 00/13] cls_u32
 cleanups and fixes.

On 2018-09-09 11:48 a.m., Al Viro wrote:

>
> BTW, shouldn't we issue u32_clear_hw_hnode() every time
> we destroy an hnode?  It's done on u32_delete(), it's
> done (for root ht) on u32_destroy(), but it's not done
> for any other hnodes when you remove the entire (not shared)
> filter.  Looks fishy...
> 

What you are saying makes sense, but that doesnt seem
like a new thing.
All hardware offload examples I have seen use root tables
only[1]. So I am not sure if they use any other tables
although the intel hardware at least seems very capable.
Look at ixgbe_main.c for example. Theres an explicit assumption
that root is always 0x800 but oresence of

+Cc some of the NIC vendor folks..



cheers,
jamal

[1]
Here's a script posted by someone at Intel(Sridhar?) a while back
that adds 2 filters, one with skip-sw and the other with skip-hw
flag.

---
    # add ingress qdisc
    tc qdisc add dev p4p1 ingress

    # enable hw tc offload.
    ethtool -K p4p1 hw-tc-offload on

    # add u32 filter with skip-sw flag.
    tc filter add dev p4p1 parent ffff: protocol ip prio 99 \
       handle 800:0:1 u32 ht 800: flowid 800:1 \
       skip-sw \
       match ip src 192.168.1.0/24 \
       action drop

    # add u32 filter with skip-hw flag.
    tc filter add dev p4p1 parent ffff: protocol ip prio 99 \
       handle 800:0:2 u32 ht 800: flowid 800:2 \
       skip-hw \
       match ip src 192.168.2.0/24 \
       action drop
----