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Date:   Thu, 16 Jul 2020 17:45:19 +0300
From:   Vladimir Oltean <olteanv@gmail.com>
To:     Xiaoliang Yang <xiaoliang.yang_1@nxp.com>
Cc:     Joergen Andreasen <joergen.andreasen@microchip.com>,
        "Allan W. Nielsen" <allan.nielsen@microchip.com>,
        Po Liu <po.liu@nxp.com>,
        Claudiu Manoil <claudiu.manoil@nxp.com>,
        Alexandru Marginean <alexandru.marginean@nxp.com>,
        Vladimir Oltean <vladimir.oltean@nxp.com>,
        Leo Li <leoyang.li@nxp.com>, Mingkai Hu <mingkai.hu@nxp.com>,
        Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jiri Pirko <jiri@resnulli.us>,
        Ido Schimmel <idosch@idosch.org>,
        Jakub Kicinski <kuba@kernel.org>,
        Vinicius Costa Gomes <vinicius.gomes@intel.com>,
        Nikolay Aleksandrov <nikolay@cumulusnetworks.com>,
        Roopa Prabhu <roopa@cumulusnetworks.com>,
        netdev <netdev@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        Horatiu Vultur <horatiu.vultur@microchip.com>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Microchip Linux Driver Support <UNGLinuxDriver@microchip.com>,
        "linux-devel@linux.nxdi.nxp.com" <linux-devel@linux.nxdi.nxp.com>
Subject: Re: [EXT] Re: [PATCH v2 net-next 03/10] net: mscc: ocelot: allocated
 rules to different hardware VCAP TCAMs by chain index
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On Thu, Jul 16, 2020 at 10:37:40AM +0000, Xiaoliang Yang wrote:
> Hi Joergen,
> 
> 
> -----Original Message-----
> From: Joergen Andreasen <joergen.andreasen@microchip.com> 
> Sent: 2020年7月16日 16:51
> 
> > >> >> Chain 0:           The default chain - today this is in IS2. If we proceed
> > >> >>                     with this as is - then this will change.
> > >> >> Chain 1-9999:      These are offloaded by "basic" classification.
> > >> >> Chain 10000-19999: These are offloaded in IS1
> > >> >>                     Chain 10000: Lookup-0 in IS1, and here we could limit the
> > >> >>                                  action to do QoS related stuff (priority
> > >> >>                                  update)
> > >> >>                     Chain 11000: Lookup-1 in IS1, here we could do VLAN
> > >> >>                                  stuff
> > >> >>                     Chain 12000: Lookup-2 in IS1, here we could apply the
> > >> >>                                  "PAG" which is essentially a GOTO.
> > >> >>
> > >> >> Chain 20000-29999: These are offloaded in IS2
> > >> >>                     Chain 20000-20255: Lookup-0 in IS2, where CHAIN-ID -
> > >> >>                                        20000 is the PAG value.
> > >> >>                     Chain 21000-21000: Lookup-1 in IS2.
> > >> >>
> > >> >> All these chains should be optional - users should only need to 
> > >> >> configure the chains they need. To make this work, we need to 
> > >> >> configure both the desired actions (could be priority update) and the goto action.
> > >> >> Remember in HW, all packets goes through this process, while in 
> > >> >> SW they only follow the "goto" path.
> > >> >>
> >>
> >> I agree with this chain assignment, following is an example to set rules:
> >>
> >> 1. Set a matchall rule for each chain, the last chain do not need goto chain action.
> >> # tc filter add dev swp0 chain 0 flower skip_sw action goto chain 10000
> >> # tc filter add dev swp0 chain 10000 flower skip_sw action goto chain 21000
> >> In driver, use these rules to register the chain.
> >>
> >> 2. Set normal rules.
> >> # tc filter add dev swp0 chain 10000 protocol 802.1Q parent ffff: flower skip_sw vlan_id 1 vlan_prio 1 action skbedit priority 1 action goto chain 21000
> >> # tc filter add dev swp0 chain 21000 protocol 802.1Q parent ffff: flower skip_sw vlan_id 1 vlan_prio 1 action drop
> >>
> >> In driver, we check if the chain ID has been registered, and goto
> >> chain is the same as first matchall rule, if is not, then return
> >> error. Each rule need has goto action except last chain.
> >>
> >> I also have check about chain template, it can not set an action
> >> template for each chain, so I think it's no use for our case. If
> >> this way to set rules is OK, I will update the patch to do as this.
> >>
> >> Thanks,
> >> Xiaoliang Yang
> >
> 
> > I agree that you cannot set an action template for each chain but
> > you can set a match template which for example can be used for
> > setting up which IS1 key to generate for the device/port.
> > The template ensures that you cannot add an illegal match.
> > I have attached a snippet from a testcase I wrote in order to test these ideas.
> > Note that not all actions are valid for the hardware.
> >
> > SMAC       = "00:00:00:11:11:11"
> > DMAC       = "00:00:00:dd:dd:dd"
> > VID1       = 0x10
> > VID2       = 0x20
> > PCP1       = 3
> > PCP2       = 5
> > DEI        = 1
> > SIP        = "10.10.0.1"
> > DIP        = "10.10.0.2"
> >
> > IS1_L0     = 10000 # IS1 lookup 0
> > IS1_L1     = 11000 # IS1 lookup 1
> > IS1_L2     = 12000 # IS1 lookup 2
> >
> > IS2_L0     = 20000 # IS2 lookup 0 # IS2 20000 - 20255 -> pag 0-255
> > IS2_L0_P1  = 20001 # IS2 lookup 0 pag 1
> > IS2_L0_P2  = 20002 # IS2 lookup 0 pag 2
> >
> > IS2_L1     = 21000 # IS2 lookup 1
> >
> > $skip = "skip_hw" # or "skip_sw"
> >
> > test "Chain templates and goto" do
> >     t_i "'prio #' sets the sequence of filters. Lowest number = highest priority = checked first. 0..0xffff"
> >     t_i "'handle #' is a reference to the filter. Use this is if you need to reference the filter later. 0..0xffffffff"
> >     t_i "'chain #' is the chain to use. Chain 0 is the default. Different chains can have different templates. 0..0xffffffff"
> >     $ts.dut.run "tc qdisc add dev #{$dp[0]} clsact"
> >
> >     t_i "Add templates"
> >     t_i "Configure the VCAP port configuration to match the shortest key that fulfill the purpose"
> 
> >     t_i "Create a template that sets IS1 lookup 0 to generate S1_NORMAL with S1_DMAC_DIP_ENA"
> >     t_i "If you match on both src and dst you will generate S1_7TUPLE"
> >     $ts.dut.run "tc chain add dev #{$dp[0]} ingress protocol ip chain #{IS1_L0} flower #{$skip} "\
> >                 "dst_mac 00:00:00:00:00:00 "\
> >                 "dst_ip 0.0.0.0 "
> >
> >     t_i "Create a template that sets IS1 lookup 1 to generate S1_5TUPLE_IP4"
> >     $ts.dut.run "tc chain add dev #{$dp[0]} ingress protocol ip chain #{IS1_L1} flower #{$skip} "\
> >                 "src_ip 0.0.0.0 "\
> >                 "dst_ip 0.0.0.0 "
> >
> >     t_i "Create a template that sets IS1 lookup 2 to generate S1_DBL_VID"
> >     $ts.dut.run "tc chain add dev #{$dp[0]} ingress protocol 802.1ad chain #{IS1_L2} flower #{$skip} "\
> >                 "vlan_id 0 "\
> >                 "vlan_prio 0 "\
> >                 "vlan_ethtype 802.1q "\
> >                 "cvlan_id 0 "\
> >                 "cvlan_prio 0 "
> >
> >     $ts.dut.run "tc chain show dev #{$dp[0]} ingress"
> 
> Why you set different filter keys on different lookup? Each lookup
> only filter one type of keys?
> If I want to filter a same key like dst_mac and do both QoS classified
> action and vlan modify action, how to implement this in the same chain
> #{IS1_L0} ?
> 
> I think it's more reasonable to distinguish different lookup by different action like this:
> IS1_L0     = 10000 # IS1 lookup 0	# do QoS classified action
> IS1_L1     = 11000 # IS1 lookup 1	# do vlan modify action
> IS1_L2     = 12000 # IS1 lookup 2	# do goto PAG action
> 
> IS2_L0     = 20000 # IS2 lookup 0 # IS2 20000 - 20255 -> pag 0-255
> IS2_L1 	  = 21000 # IS2 lookup 1
> 
> So it’s no need to add templates, each lookup can support filtering
> mac, IP or vlan tag, but only support one action.
> 
> Thanks,
> Xiaoliang

As far as I understand, he's still using the static chain numbers
exactly for that, even though he didn't explicitly mention the action
for each individual IS1 lookup.

The reason why he's also adding templates on each individual chain is to
be able to configure VCAP_S1_KEY_CFG and VCAP_S2_CFG. The configuration
of key type is per lookup.

Honestly, Joergen, I would take dynamic key configuration per lookup as
a separate item. Xiaoliang's patch series for IS1 support is pretty
large already.

Right now we have:

- In mainline:

S2_IP6_CFG
S2_IP6_CFG controls the key generation for IPv6 frames. Bits 1:0
control the first lookup and bits 3:2 control the second lookup.
0: IPv6 frames are matched against IP6_TCP_UDP or IP6_OTHER entries
1: IPv6 frames are matched against IP6_STD entries
2: IPv6 frames are matched against IP4_TCP_UDP or IP4_OTHER entries
3: IPv6 frames are matched against MAC_ETYPE entries

We set this field to 0xa (0b1010, aka 2 for both lookups: IP4_TCP_UDP).
Although we don't really parse IPv6 keys coming from tc.

Also there are these fields which we're managing dynamically through
ocelot_match_all_as_mac_etype, depending on whether there is any
MAC_ETYPE key added by the user:
S2_SNAP_DIS
S2_ARP_DIS
S2_IP_TCPUDP_DIS
S2_IP_OTHER_DIS

- In Xiaoliang's patchset:

S1_KEY_IP6_CFG
Selects key per lookup in S1 for IPv6 frames.
0: Use key S1_NORMAL
1: Use key S1_7TUPLE
2: Use key S1_5TUPLE_IP4
3: Use key S1_NORMAL_IP6
4: Use key S1_5TUPLE_IP6
5: Use key S1_DBL_VID

We set this to 2.

S1_KEY_IP4_CFG
Selects key per lookup in S1 for IPv4 frames.
0: Use key S1_NORMAL
1: Use key S1_7TUPLE
2: Use key S1_5TUPLE_IP4
3: Use key S1_DBL_VID

We set this to 2.

Your input on which tc chain template could be used for each key type is
valuable, we should create a table with all the options and associated
key sizes (and therefore, number of available filters) and post it
somewhere. I'm not completely sure that chains will be enough to
describe every key type, at least not intuitively, For example if I just
want to match on EtherType (protocol), I'll need an ETYPE (IS1) or
MAC_ETYPE (IS2) rule, but the template for that will need to be
formulated in terms of dst_mac because I don't think there's a way to
use only the protocol in a template.

But I expect we keep using some default values (perhaps even the current
ones, or deduce a valid key type from the first added rule, which is
exactly what ocelot_match_all_as_mac_etype tries to do now) and don't
expect the user to open the datasheet unless some advanced configuration
is required. Otherwise I'm not sure who is going to use this. If the
user sees a template shell script with the chains already set up,
chances are it won't be too hard to add the right actions to the right
chains. But if that is going to involve fiddling with templates to set
up the right key type, when all they want is a source IPv4 address
match, well, no chance.

If we agree that templates won't be strictly necessary for basic
functionality, we can resubmit what we have already and think more about
the best way to expose all key types. I don't honestly know about using
a flower filter with 'protocol all' and no other key as a matchall
replacement. This is going to be really, really restrictive, and this
particular restriction could even be perhaps lifted in the meantime (I
don't see a reason why 'matchall' wouldn't be allowed in a chain with a
template installed).

But Xiaoliang has a point though: there is something which can never be
supported: if I want to do QoS based on a list of filters, some of which
need a S1_7TUPLE key, and others need a S1_NORMAL_IP6 key, then I can
never do that, because in our model, there's only one chain/lookup
reserved for QoS classification (a software constraint) but we need 2
chains/lookups for the 2 different key types (a hardware constraint).
Yes, this is something hypothetical at this point, but it bothers me
that the model would be limiting us. The hardware should support QoS
classification in more than 1 IS1 lookup, no? It isn't limited to
IS1_L0. Maybe, after all, we should permit dynamic assignment of actions
to chains. This way, "the QoS on multiple key types" use case could be
supported. What do you think?

Allan also mentioned shared blocks. Do we see anything particularly
difficult with those, that we should address first?

Thanks,
-Vladimir