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

[Thomas Monjalon <thomas@monjalon.net>]

11/01/2021 12:26, Zhang, Qi Z:
> From: Thomas Monjalon <thomas@monjalon.net>
> > 10/01/2021 11:46, Ori Kam:
> > > From: Zhang, Qi Z <qi.z.zhang@intel.com>
> > > > From: Thomas Monjalon <thomas@monjalon.net>
> > > > > 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%2Fto
> > > > ols.ietf
> > > > .org%2Fhtml%2Frfc7348&amp;data=04%7C01%7Corika%40nvidia.com%7C
> > 46b2
> > > >
> > d8f48944422f0d9008d8b43a2293%7C43083d15727340c1b7db39efd9ccc17a
> > %7
> > > >
> > C0%7C0%7C637457509081543237%7CUnknown%7CTWFpbGZsb3d8eyJWIjoi
> > MC
> > > >
> > 4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&a
> > > >
> > mp;sdata=RYWFMjuxkcUZ982kK2s44tBAjf%2FTkDyaa7VEybCtxOo%3D&amp;r
> > es
> > > > 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.
> 
> As I mentioned in previous, this is a device (port) level configuration, so it can only be configured by a PF driver or a privileged VF base on our security model.
> A typical usage in a NFV environment could be:
> 
> 1. A privileged VF (e.g. ice_dcf PMD) use rte_eth_dev_udp_tunnel_port_add to create tunnel port for eCPRI, them this will impact on all VFs in the same PF.
> 2. A normal VF driver can create rte_flow rule that match specific patch for queue steering or apply RSS for eCPRI packets, but it DON'T have the permission to define the tunnel port.

Whaooh! A normal Intel VF is not allowed to match the tunnel it wants
if not enabled by a priviledged VF?
I would say it is a HW design flaw, but that's not the question.

> So it does not help to have a rte_flow that match dst udp port
> as tunnel while have an action in the same rule.

Now I understand you are truly looking for a device configuration.
But as it looks more as a HW limitation,
I don't think it should be part of ethdev.
The fact is that it is already part of ethdev...

I don't know what to say. I need to digest how Intel limitation
is "still" trying to drive some parts of the "generic" API.


> > > > #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.