RE: [PATCH v2] doc: fix support table for ETH and VLAN flow items

[Ori Kam <orika@nvidia.com>]

> -----Original Message-----
> From: fengchengwen <fengchengwen@huawei.com>
> Sent: Monday, 17 October 2022 14:55
> 
> Thanks Ilya and Eli
> 
> On 2022/10/16 13:26, Eli Britstein wrote:
> >
> >
> >> -----Original Message-----
> >> From: Ilya Maximets <i.maximets@ovn.org>
> >> Sent: Friday, October 14, 2022 3:37 PM
> >> To: fengchengwen <fengchengwen@huawei.com>; dev@dpdk.org; Ori
> Kam
> >> <orika@nvidia.com>; NBU-Contact-Thomas Monjalon (EXTERNAL)
> >> <thomas@monjalon.net>; Eli Britstein <elibr@nvidia.com>
> >> Cc: i.maximets@ovn.org; Ajit Khaparde <ajit.khaparde@broadcom.com>;
> >> Somnath Kotur <somnath.kotur@broadcom.com>; Rahul Lakkireddy
> >> <rahul.lakkireddy@chelsio.com>; Hemant Agrawal
> >> <hemant.agrawal@nxp.com>; Sachin Saxena
> <sachin.saxena@oss.nxp.com>;
> >> Simei Su <simei.su@intel.com>; Wenjun Wu <wenjun1.wu@intel.com>;
> John
> >> Daley <johndale@cisco.com>; Hyong Youb Kim <hyonkim@cisco.com>;
> Ziyang
> >> Xuan <xuanziyang2@huawei.com>; Xiaoyun Wang
> >> <cloud.wangxiaoyun@huawei.com>; Guoyang Zhou
> >> <zhouguoyang@huawei.com>; Dongdong Liu
> <liudongdong3@huawei.com>;
> >> Yisen Zhuang <yisen.zhuang@huawei.com>; Yuying Zhang
> >> <Yuying.Zhang@intel.com>; Beilei Xing <beilei.xing@intel.com>; Jingjing
> Wu
> >> <jingjing.wu@intel.com>; Qiming Yang <qiming.yang@intel.com>; Qi
> Zhang
> >> <qi.z.zhang@intel.com>; Junfeng Guo <junfeng.guo@intel.com>; Rosen
> Xu
> >> <rosen.xu@intel.com>; Matan Azrad <matan@nvidia.com>; Slava
> Ovsiienko
> >> <viacheslavo@nvidia.com>; Liron Himi <lironh@marvell.com>; Jiawen Wu
> >> <jiawenwu@trustnetic.com>; Jian Wang <jianwang@trustnetic.com>;
> Dekel
> >> Peled <dekelp@nvidia.com>; stable@dpdk.org
> >> Subject: Re: [PATCH v2] doc: fix support table for ETH and VLAN flow items
> >>
> >> External email: Use caution opening links or attachments
> >>
> >>
> >> On 10/14/22 11:41, fengchengwen wrote:
> >>> Hi Ilya,
> >>>
> >>>    I have some questions about has_vlan/has_more_vlan fields:
> >>
> >> I think, these questions are more for rte_flow maintainers, but I'll try
> answer.
> >> Maintainers can correct me if I'm wrong.
> >>
> >>>
> >>>    a\ DPDK framework support cvlan-tag(0x8100) and svlan-tag(0x88A8),
> >>> and also deprecated qinq-tag(eg. 0x9100)
> >>
> >> Didn't check, but sounds about right.
> > It is not related to "DPDK framework". It is up to the HW to determine.
> >>
> >>>    b\ If has_vlan is used, does it mean that all the VLAN
> >> tags(0x8100/88A8/9100) must be matched ?
> >>>       I think this is different from using type, which can only match one of
> >> them.
> >>
> >> I think so.  has_vlan = 1 means that packet has some vlan regardless of the
> >> actual type of the vlan header.
> > Again, it is up to the HW.
> >>
> >>>    c\ And has_more_vlan has the same function as has_vlan ?
> >>
> >> Yes, from my understanding, 'has_more_vlan' is the same as 'has_vlan',
> but
> >> for the 'inner_type'.
> >>
> >>>    d\ What the problems are solved by the new two fields?
> >>
> >> One of the problems we solved in OVS by using these fields is that we
> need a
> >> way to match on the fact that there is a vlan, but we do not care what this
> vlan
> >> tag is and at the same time we want to match on the inner type for such
> >> packets.
> >>
> >> Trying to workaround that situation will likely require breaking the 1:1
> >> mapping between OVS flows and rte_flow rules, so it is not really
> possible.  In
> >> the end, we had to use 'has_vlan' field to fix an incorrect packet matching
> in
> >> OVS.  Alternative, I guess, would be to just not offload vlan flows, but
> doesn't
> >> make a lot of sense.
> >>
> >> Eli should know better what was the actual problem, I think.
> > OVS does not support offload of qinq, so "has_more_vlan" is still not in
> use.
> > For native (untagged) flows, there is a need to tell the HW "has_vlan is 0",
> otherwise the HW flow will hit both tagged/untagged traffic, which is wrong.
> > For tagged flows, OVS will always match on the VLAN properties, so
> "has_vlan is 1" can be deducted/implicit.
> > Before that field existed, it could be implicit to deduct "lack" of VLAN
> header (e.g. "eth / ipv4" for example) as "has_vlan is 0". However, other
> applications that would like both tagged/untagged traffic to hit needed to
> have 2 separated flows (with a probably slightly lower performance).
> 
> Got it, Thanks.
> 
> > Also, DPDK rte-flow is to have things explicit.
> >>
> >>>
> >>>
> >>>    If the above understanding is correct, and the hardware support
> identify
> >> there TPID(cvlan-0x8100, svlan-0x88A8, dqing-0x9100) as VLAN, then:
> >>>      Rule: eth has_vlan is 1 / vlan vid is 100 / ipv4 / end actions xxx
> >>>      Result: all ipv4 packets with at least one VLAN(the TPID can be one of
> the
> >> above) and the vid is 100 can be matched.
> >>>

Right, just to be extra clear the vid == 100 is for the outer most.
 
> >>>      Rule: eth type is 0x8100 / vlan vid is 100 / ipv4 / end actions xxx
> >>>      Result: all ipv4 packets with at lease one VLAN(which TPID must be
> >> 0x8100) and the vid is 100 can be matched.
> >>>

Right,

> >>>      Rule: eth has_vlan is 1 / vlan vid is 100 has_more_vlan is 1 / vlan vid is
> 200
> >> / ipv4 / end action xxx
> >>>      Result: all ipv4 packets with at least two VLAN(the TPID can be one of
> the
> >> above) and outer vid is 100 and the next vid is 200 can be matched.
> >>>

Right, but you don't need to use the has_vlan since vlan item is given in the pattern.

> >>>      Rule: eth type is 0x88A8 / vlan vid is 100 inner_type is 0x8100 / vlan
> vid is
> >> 200 / ipv4 / end action xxx
> >>>      Result: all ipv4 packets with at least two VLAN(the first TPID is 0x88A8
> and
> >> second TPID is 0x8100) and outer vid is 100 and the next vid is 200 can be
> >> matched.
> >>>    Is the above result correct ?
> >>
> >> Seems correct, but I don't have much experience with rte_flow notations.
> >>
> >> Ori, could you comment on this?
> 

Yes, everything looks good.

> Assuming that A is the number of VLANs by flow creation,
> and B is the number of VLANs of real flow
> 
> What I'm concerned about is: Whether the matching is successful only when
> A is equal to B?
> 
> In addition, the maximum number of VLANs that can be parsed by hardware
> is limited,
> For example, if the hardware supports a maximum of two VLAN tags, a rule
> with the number
> of two VLAN tags is created for the RTE_Flow. However, the actual flow has
> more than two
> VLAN tags. Can this situation be matched?
> 
> Hi Ori, Could you check on this?
> 

A must be smaller than B and the last  vlan has_more = 1
The matching is based on HW limitations, it depends on how the HW works.
> >>
> >> Best regards, Ilya Maximets.
> >>
> >>>
> >>> Thanks
> >>>
> >>> On 2022/10/13 18:48, Ilya Maximets wrote:
> >>>> 'has_vlan' attribute is only supported by sfc, mlx5 and cnxk.
> >>>> Other drivers doesn't support it.  Most of them (like i40e) just
> >>>> ignore it silently.  Some drivers (like mlx4) never had a full
> >>>> support of the eth item even before introduction of 'has_vlan'
> >>>> (mlx4 allows to match on the destination MAC only).
> >>>>
> >>>> Same for the 'has_more_vlan' flag of the vlan item.
> >>>>
> >>>> 'has_vlan' is part of 'rte_flow_item_eth', so changing 'eth'
> >>>> field to 'partial support' in documentation for all such drivers.
> >>>> 'has_more_vlan' is part of 'rte_flow_item_vlan', so changing 'vlan'
> >>>> to 'partial support' as well.
> >>>>
> >>>> This doesn't solve the issue, but at least marks the problematic
> >>>> drivers.
> >>>>
> >>>> Some details are available in:
> >>>>   https://bugs.dpdk.org/show_bug.cgi?id=958
> >>>>
> >>>> Fixes: 09315fc83861 ("ethdev: add VLAN attributes to ethernet and
> >>>> VLAN items")
> >>>> Cc: stable@dpdk.org
> >>>>
> >>>> Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
> >>>> ---
> >>>>
> >>>> Version 2:
> >>>>   - Rebased on a current main branch.
> >>>>   - Added more clarifications to the commit message.
> >>>>
> >>>> I added the stable in CC, but the patch should be extended while
> >>>> backporting.  For 21.11 the cnxk driver should be also updated, for
> >>>> 20.11, sfc driver should also be included.
> >>>>
> >>>>  doc/guides/nics/features/bnxt.ini   | 4 ++--
> >>>>  doc/guides/nics/features/cxgbe.ini  | 4 ++--
> >>>> doc/guides/nics/features/dpaa2.ini  | 4 ++--
> >>>> doc/guides/nics/features/e1000.ini  | 2 +-
> >>>>  doc/guides/nics/features/enic.ini   | 4 ++--
> >>>>  doc/guides/nics/features/hinic.ini  | 2 +-
> >>>>  doc/guides/nics/features/hns3.ini   | 4 ++--
> >>>>  doc/guides/nics/features/i40e.ini   | 4 ++--
> >>>>  doc/guides/nics/features/iavf.ini   | 4 ++--
> >>>>  doc/guides/nics/features/ice.ini    | 4 ++--
> >>>>  doc/guides/nics/features/igc.ini    | 2 +-
> >>>>  doc/guides/nics/features/ipn3ke.ini | 4 ++--
> >>>> doc/guides/nics/features/ixgbe.ini  | 4 ++--
> >>>>  doc/guides/nics/features/mlx4.ini   | 4 ++--
> >>>>  doc/guides/nics/features/mvpp2.ini  | 4 ++--
> >>>>  doc/guides/nics/features/tap.ini    | 4 ++--
> >>>>  doc/guides/nics/features/txgbe.ini  | 4 ++--
> >>>>  17 files changed, 31 insertions(+), 31 deletions(-)
> >