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

[fengchengwen <fengchengwen@huawei.com>]

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.
>>>
>>>      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.
>>>
>>>      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.
>>>
>>>      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?

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?

>>
>> 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(-)
>