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

[Andrew Rybchenko <arybchenko@solarflare.com>]

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.

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

Andrew.