netdev - Re: [PATCH net-next 0/2] net: stmmac: add EthType Rx Frame steering

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Message-ID: <20211210115730.bcdh7jvwt24u5em3@skbuf>
Date:   Fri, 10 Dec 2021 13:57:30 +0200
From:   Vladimir Oltean <olteanv@...il.com>
To:     Ong Boon Leong <boon.leong.ong@...el.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Jose Abreu <joabreu@...opsys.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        alexandre.torgue@...s.st.com,
        Kurt Kanzenbach <kurt.kanzenbach@...utronix.de>,
        netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH net-next 0/2] net: stmmac: add EthType Rx Frame steering

Hi David, Jakub,

On Thu, Dec 09, 2021 at 11:16:29PM +0800, Ong Boon Leong wrote:
> Hi,
> 
> Patch 1/2: Fixes issue in tc filter delete flower for VLAN priority
>            steering. Patch has been sent to 'net' ML. Link as follow:
> 
> https://patchwork.kernel.org/project/netdevbpf/patch/20211209130335.81114-1-boon.leong.ong@intel.com/
> 
> Patch 2/2: Patch to add LLDP and IEEE1588 EtherType RX frame steering
>            in tc flower that is implemented on-top of patch 1/2.
> 
> Below are the test steps for checking out the newly added feature:-
> 
> # Setup traffic class and ingress filter
> $ IFDEVNAME=eth0
> $ tc qdisc add dev $IFDEVNAME ingress
> $ tc qdisc add dev $IFDEVNAME root mqprio num_tc 8 \
>      map 0 1 2 3 4 5 6 7 0 0 0 0 0 0 0 0 \
>      queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 hw 0
> 
> # Add two VLAN priority based RX Frame Steering
> $ tc filter add dev $IFDEVNAME parent ffff: protocol 802.1Q \
>      flower vlan_prio 1 hw_tc 1
> $ tc filter add dev $IFDEVNAME parent ffff: protocol 802.1Q \
>      flower vlan_prio 2 hw_tc 2
> 
> # For LLDP
> $ tc filter add dev $IFDEVNAME parent ffff: protocol 0x88cc \
>      flower hw_tc 5
> 
> # For PTP
> $ tc filter add dev $IFDEVNAME parent ffff: protocol 0x88f7 \
>      flower hw_tc 6
> 
> # Show the ingress tc filters
> $ tc filter show dev $IFDEVNAME ingress
> 
> filter parent ffff: protocol ptp pref 49149 flower chain 0
> filter parent ffff: protocol ptp pref 49149 flower chain 0 handle 0x1 hw_tc 6
>   eth_type 88f7
>   in_hw in_hw_count 1
> filter parent ffff: protocol LLDP pref 49150 flower chain 0
> filter parent ffff: protocol LLDP pref 49150 flower chain 0 handle 0x1 hw_tc 5
>   eth_type 88cc
>   in_hw in_hw_count 1
> filter parent ffff: protocol 802.1Q pref 49151 flower chain 0
> filter parent ffff: protocol 802.1Q pref 49151 flower chain 0 handle 0x1 hw_tc 2
>   vlan_prio 2
>   in_hw in_hw_count 1
> filter parent ffff: protocol 802.1Q pref 49152 flower chain 0
> filter parent ffff: protocol 802.1Q pref 49152 flower chain 0 handle 0x1 hw_tc 1
>   vlan_prio 1
>   in_hw in_hw_count 1
> 
> # Delete tc filters
> $ tc filter del dev $IFDEVNAME parent ffff: pref 49149
> $ tc filter del dev $IFDEVNAME parent ffff: pref 49150
> $ tc filter del dev $IFDEVNAME parent ffff: pref 49151
> $ tc filter del dev $IFDEVNAME parent ffff: pref 49152
> 
> Thanks,
> BL
> 
> Ong Boon Leong (2):
>   net: stmmac: fix tc flower deletion for VLAN priority Rx steering
>   net: stmmac: add tc flower filter for EtherType matching
> 
>  drivers/net/ethernet/stmicro/stmmac/stmmac.h  |  20 ++
>  .../net/ethernet/stmicro/stmmac/stmmac_tc.c   | 189 +++++++++++++++++-
>  2 files changed, 205 insertions(+), 4 deletions(-)
> 
> -- 
> 2.25.1
> 

Is it the canonical approach to perform flow steering via tc-flower hw_tc,
as opposed to ethtool --config-nfc? My understanding from reading the
documentation is that tc-flower hw_tc only selects the hardware traffic
class for a packet, and that this has to do with prioritization
(although the concept in itself is a bit ill-defined as far as I
understand it, how does it relate to things like offloaded skbedit priority?).
But selecting a traffic class, in itself, doesn't (directly or
necessarily) select a ring per se, as ethtool does? Just like ethtool
doesn't select packet priority, just RX queue. When the RX queue
priority is configurable (see the "snps,priority" device tree property
in stmmac_mtl_setup) and more RX queues have the same priority, I'm not
sure what hw_tc is supposed to do in terms of RX queue selection?