Re: [dpdk-dev] [dpdk-dev v2 1/2] ethdev: add new tunnel type for ecpri

[Thomas Monjalon <thomas@monjalon.net>]

10/01/2021 11:46, Ori Kam:
> Hi,
> 
> > -----Original Message-----
> > From: Zhang, Qi Z <qi.z.zhang@intel.com>
> > Sent: Saturday, January 9, 2021 3:01 AM
> > Subject: RE: [dpdk-dev] [dpdk-dev v2 1/2] ethdev: add new tunnel type for ecpri
> > 
> > 
> > 
> > > -----Original Message-----
> > > From: Thomas Monjalon <thomas@monjalon.net>
> > > Subject: Re: [dpdk-dev] [dpdk-dev v2 1/2] ethdev: add new tunnel type for
> > ecpri
> > >
> > > 08/01/2021 10:29, Andrew Rybchenko:
> > > > On 1/8/21 11:57 AM, Ferruh Yigit wrote:
> > > > > On 1/8/2021 1:41 AM, Zhang, Qi Z wrote:
> > > > >> From: Thomas Monjalon <thomas@monjalon.net>
> > > > >>> 07/01/2021 16:24, Zhang, Qi Z:
> > > > >>>> From: Thomas Monjalon <thomas@monjalon.net>
> > > > >>>>> 07/01/2021 13:47, Zhang, Qi Z:
> > > > >>>>>> From: Thomas Monjalon <thomas@monjalon.net>
> > > > >>>>>>> 07/01/2021 10:32, Guo, Jia:
> > > > >>>>>>>> From: Thomas Monjalon <thomas@monjalon.net>
> > > > >>>>>>>>> 24/12/2020 07:59, Jeff Guo:
> > > > >>>>>>>>>> --- a/lib/librte_ethdev/rte_ethdev.h
> > > > >>>>>>>>>> +++ b/lib/librte_ethdev/rte_ethdev.h
> > > > >>>>>>>>>> @@ -1219,6 +1219,7 @@ enum rte_eth_tunnel_type {
> > > > >>>>>>>>>>       RTE_TUNNEL_TYPE_IP_IN_GRE,
> > > > >>>>>>>>>>       RTE_L2_TUNNEL_TYPE_E_TAG,
> > > > >>>>>>>>>>       RTE_TUNNEL_TYPE_VXLAN_GPE,
> > > > >>>>>>>>>> +    RTE_TUNNEL_TYPE_ECPRI,
> > > > >>>>>>>>>>       RTE_TUNNEL_TYPE_MAX,
> > > > >>>>>>>>>>   };
> > > > >>>>>>>>>
> > > > >>>>>>>>> We tried to remove all these legacy API in DPDK 20.11.
> > > > >>>>>>>>> Andrew decided to not remove this one because it is not yet
> > > > >>>>>>>>> completely replaced by rte_flow in all drivers.
> > > > >>>>>>>>> However, I am against continuing to update this API.
> > > > >>>>>>>>> The opposite work should be done: migrate to rte_flow.
> > > > >>>>>>>>
> > > > >>>>>>>> Agree but seems that the legacy api and driver legacy
> > > > >>>>>>>> implementation still keep in this release, and there is no a
> > > > >>>>>>>> general way to replace the legacy by rte_flow right now.
> > > > >>>>>>>
> > > > >>>>>>> I think rte_flow is a complete replacement with more features.
> > > > >>>>>>
> > > > >>>>>> Thomas, I may not agree with this.
> > > > >>>>>>
> > > > >>>>>> Actually the "enum rte_eth_tunnel_type" is used by
> > > > >>>>>> rte_eth_dev_udp_tunnel_port_add A packet with specific dst udp
> > > > >>>>>> port will be recognized as a specific tunnel packet type (e.g.
> > > > >>>>>> vxlan, vxlan-gpe,
> > > > >>>>> ecpri...) In Intel NIC, the API actually changes the
> > > > >>>>> configuration of the packet parser in HW but not add a filter
> > > > >>>>> rule and I guess all other devices may enable it in a similar way.
> > > > >>>>>> so naturally it should be a device (port) level configuration
> > > > >>>>>> but not a rte_flow
> > > > >>>>> rule for match, encap, decap...
> > > > >>>>>
> > > > >>>>> I don't understand how it helps to identify an UDP port if there
> > > > >>>>> is no rule for this tunnel.
> > > > >>>>> What is the usage?
> > > > >>>>
> > > > >>>> Yes, in general It is a rule, it matches a udp packet's dst port
> > > > >>>> and the action is
> > > > >>> "now the packet is identified as vxlan packet" then all other
> > > > >>> rte_flow rules that match for a vlxan as pattern will take effect.
> > > > >>> but somehow, I think they are not rules in the same domain, just
> > > > >>> like we have dedicate API for mac/vlan filter, we'd better have a
> > > > >>> dedicate API for this also. ( RFC for Vxlan explains why we need
> > > > >>> this.
> > https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftools.ietf
> > .org%2Fhtml%2Frfc7348&amp;data=04%7C01%7Corika%40nvidia.com%7C46b2
> > d8f48944422f0d9008d8b43a2293%7C43083d15727340c1b7db39efd9ccc17a%7
> > C0%7C0%7C637457509081543237%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC
> > 4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&a
> > mp;sdata=RYWFMjuxkcUZ982kK2s44tBAjf%2FTkDyaa7VEybCtxOo%3D&amp;res
> > erved=0).
> > > > >>>>
> > > > >>>> "Destination Port: IANA has assigned the value 4789 for the VXLAN
> > > > >>>> UDP port, and this value SHOULD be used by default as the
> > > > >>>> destination UDP port.  Some early implementations of VXLAN have
> > > > >>>> used other values for the destination port.  To enable
> > > > >>>> interoperability with these implementations, the destination port
> > > SHOULD be configurable."
> > > > >>>
> > > > >>> Yes the port number is free.
> > > > >>> But isn't it more natural to specify this port number as part of
> > > > >>> the rte_flow rule?
> > > > >>
> > > > >> I think if we have a rte_flow action type that can be used to set a
> > > > >> packet's tunnel type xxx, like below #flow create eth/ipv4/udp port
> > > > >> is 4789/... action set_tunnel_type VxLAN / end then we may replace
> > > > >> it with rte_flow, but I'm not sure if it's necessary, please share
> > > > >> if you have a better idea.
> > >
> > > Of course we can specify the UDP port in rte_flow rule.
> > > Please check rte_flow_item_udp.
> > > That's a basic of rte_flow.
> > 
> > Its not about the pattern match, it's about the action, what we need is a
> > rte_flow action to "define a packet's tunnel type", but we don't have.

A packet type alone is meaningless.
It is always associated to an action, this is what rte_flow does.


> > #flow create eth/ipv4/udp port is 4789/... action set_tunnel_type VxLAN
> > 
> > I think rte_eth_dev_udp_tunnel_port_add does this job well already, if we plan
> > to move it to rte_flow, at least we need a replacement solution.

The documentation does not say why it is useful.
With rte_flow you don't need it because a flow is specified with its action.


> Let me see if I understand it correctly.
> In your case, the issue is that you need to configure the HW to parse the packet correctly right?
> It is not about the matching it is about the configuration of the HW, you wish to tell
> the HW that the packet should be parsed by different means correct?
> 
> If this is the case it sounds to me that you should use rte_flow and if the 
> user adds the following rule:
> #flow create pattern eth / ivp4 / udp port is 4789 / .. action .....
> You simply need to configure your HW to support the ecpri configuration.
> 
> 
> > >
> > >
> > > > > Isn't this more a device configuration than filtering, not sure
> > > > > about using rte_flow for this.
> > > >
> > > > +1
> > >
> > > A device configuration? No, setting an UDP port is a stack configuration.
> > >
> > >
> > > > >> BTW, are we going to move all other filter like mac , VLAN
> > > > >> filter/strip/insert into rte_flow finally?
> > >
> > > Yes I think it should be the direction.
> > > All of this can be achieved with rte_flow.
> > >
> > >
> > > > >> if that's the plan, though I don't have much inputs for this right
> > > > >> now, but I think we may not need to prevent new features be added
> > > > >> based on current API if it does not introduce more complexity and
> > > > >> not break anything.
> > >
> > > If we continue updating old API, we are just forking ourself:
> > > having 2 APIs for the same feature is a non-sense.
> > > We must remove APIs which are superseded by rte_flow.
> > >
> 
>