Re: [dpdk-dev] [PATCH v4 1/3] ethdev: add raw encapsulation action

[Ori Kam <orika@mellanox.com>]

> -----Original Message-----
> From: Andrew Rybchenko <arybchenko@solarflare.com>
> Sent: Monday, October 22, 2018 4:06 PM
> To: Ori Kam <orika@mellanox.com>; wenzhuo.lu@intel.com;
> jingjing.wu@intel.com; bernard.iremonger@intel.com; ferruh.yigit@intel.com;
> stephen@networkplumber.org; Adrien Mazarguil
> <adrien.mazarguil@6wind.com>
> Cc: dev@dpdk.org; Dekel Peled <dekelp@mellanox.com>; Thomas Monjalon
> <thomas@monjalon.net>; Nélio Laranjeiro <nelio.laranjeiro@6wind.com>;
> Yongseok Koh <yskoh@mellanox.com>; Shahaf Shuler
> <shahafs@mellanox.com>
> Subject: Re: [dpdk-dev] [PATCH v4 1/3] ethdev: add raw encapsulation action
> 
> On 10/17/18 11:43 AM, Ori Kam wrote:
> >> -----Original Message-----
> >> From: Andrew Rybchenko <arybchenko@solarflare.com>
> >> Sent: Wednesday, October 17, 2018 10:56 AM
> >> To: Ori Kam <orika@mellanox.com>; wenzhuo.lu@intel.com;
> >> jingjing.wu@intel.com; bernard.iremonger@intel.com;
> ferruh.yigit@intel.com;
> >> stephen@networkplumber.org; Adrien Mazarguil
> >> <adrien.mazarguil@6wind.com>
> >> Cc: dev@dpdk.org; Dekel Peled <dekelp@mellanox.com>; Thomas Monjalon
> >> <thomas@monjalon.net>; Nélio Laranjeiro <nelio.laranjeiro@6wind.com>;
> >> Yongseok Koh <yskoh@mellanox.com>; Shahaf Shuler
> >> <shahafs@mellanox.com>
> >> Subject: Re: [dpdk-dev] [PATCH v4 1/3] ethdev: add raw encapsulation action
> >>
> >> On 10/17/18 12:41 AM, Ori Kam wrote:
> >> Currenlty the encap/decap actions only support encapsulation
> >> of VXLAN and NVGRE L2 packets (L2 encapsulation is where
> >> the inner packet has a valid Ethernet header, while L3 encapsulation
> >> is where the inner packet doesn't have the Ethernet header).
> >> In addtion the parameter to to the encap action is a list of rte items,
> >> this results in 2 extra translation, between the application to the
> >> actioni and from the action to the NIC. This results in negetive impact
> >> on the insertion performance.
> >>
> >> Looking forward there are going to be a need to support many more tunnel
> >> encapsulations. For example MPLSoGRE, MPLSoUDP.
> >> Adding the new encapsulation will result in duplication of code.
> >> For example the code for handling NVGRE and VXLAN are exactly the same,
> >> and each new tunnel will have the same exact structure.
> >>
> >> This patch introduce a raw encapsulation that can support L2 tunnel types
> >> and L3 tunnel types. In addtion the new
> >> encapsulations commands are using raw buffer inorder to save the
> >> converstion time, both for the application and the PMD.
> >>
> >> In order to encapsulate L3 tunnel type there is a need to use both
> >> actions in the same rule: The decap to remove the L2 of the original
> >> packet, and then encap command to encapsulate the packet with the
> >> tunnel.
> >> For decap L3 there is also a need to use both commands in the same flow
> >> first the decap command to remove the outer tunnel header and then encap
> >> to add the L2 header.
> >>
> >> Signed-off-by: Ori Kam mailto:orika@mellanox.com
> 
> [...]
> 
> >> +
> >> +This action modifies the payload of matched flows. The data supplied must
> >> +be a valid header, either holding layer 2 data in case of removing layer 2
> >> +before incapsulation of layer 3 tunnel (for example MPLSoGRE) or
> complete
> >> +tunnel definition starting from layer 2 and moving to the tunel item itself.
> >> +When applied to the original packet the resulting packet must be a
> >> +valid packet.
> >> +
> >> +.. _table_rte_flow_action_raw_decap:
> >> +
> >> +.. table:: RAW_DECAP
> >> +
> >> +   +----------------+----------------------------------------+
> >> +   | Field          | Value                                  |
> >> +   +================+========================================+
> >> +   | ``data``       | Decapsulation data                     |
> >>
> >> Sorry, I've missed the point why it is here. Is it used for matching?
> >> Why is the size insufficient?
> >>
> > No it is not used for matching this is only for the encapsulation data.
> > The data is for PMD that needs to validate that they can decapsulate
> > The packet, and on some PMD there might need the specify which headers
> > to remove and not just number of bytes.
> 
> Sorry, but I still don't understand. How should PMD or HW use it?
> I guess the main problem here is that it is a generic action.
> If it is VXLAN_DECAP, it would not be a problem and neither
> size nor data would be required.
> 

The data is buffer of the encap/decap headers, so the PMD can parse the this data
and check the validity and if the HW supports it.
Some NICs will not use this others can check if the tunnel request is valid.
For example let's assume that some tunnel encapsulation is supported on some FW version
and not supported in other version so the PMD can check the encapsulation data to see 
what is the requested tunnel type and the FW capabilities to return success or fail.

This was one of Adrien requests, 

> >> +   +----------------+----------------------------------------+
> >> +   | ``size``       | Size of data                           |
> >> +   +----------------+----------------------------------------+
> >> +
> >>   Action: ``SET_IPV4_SRC``
> >>   ^^^^^^^^^^^^^^^^^^^^^^^^
> 
> Andrew.

Thanks,
Ori