Re: [dpdk-dev] [PATCH v3 3/4] ethdev: add TTL change actions in flow API

[Shahaf Shuler <shahafs@mellanox.com>]

Hi Qi,

Am wondering if we can make the below more generic and not tailored for specific use cases. 

Monday, April 16, 2018 8:17 AM, Qi Zhang:
> Subject: [dpdk-dev] [PATCH v3 3/4] ethdev: add TTL change actions in flow
> API
> 
> Add couple OpenFlow frienldy TTL change actions.
> 
> RTE_FLOW_ACTION_MLPS_TTL_DEC - decrement MPLS TTL.
> RTE_FLOW_ACTION_IP_TTL_DEC - decrement IP TTL.
> RTE_FLOW_ACTION_TTL_COPY_OUT - copy TTL outwards.
> RTE_FLOW_ACTION_TTL_COPY_IN - copy TTL inwards.
> 
> Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
> ---
>  app/test-pmd/cmdline_flow.c                 | 64 +++++++++++++++++++++++
>  doc/guides/prog_guide/rte_flow.rst          | 80
> +++++++++++++++++++++++++++++
>  doc/guides/testpmd_app_ug/testpmd_funcs.rst | 12 +++++
>  lib/librte_ether/rte_flow.h                 | 77 +++++++++++++++++++++++++++
>  4 files changed, 233 insertions(+)

[...]

> 
>  /** Remove and return last entry from argument stack. */ diff --git
> a/doc/guides/prog_guide/rte_flow.rst
> b/doc/guides/prog_guide/rte_flow.rst
> index ea0e40a52..e81f0e375 100644
> --- a/doc/guides/prog_guide/rte_flow.rst
> +++ b/doc/guides/prog_guide/rte_flow.rst
> @@ -1588,6 +1588,86 @@ contain respective protocol layer.
>     |  ``mask``     | Bit-mask applied to new_val                                       |
>     +---------------+-------------------------------------------------------------------+
> 
> +Action: ``MPLS_TTL_DEC``
> +^^^^^^^^^^^^^^^^^^^^^^^^
> +
> +Decrement MPLS TTL, only applies to packets that contain specific MPLS
> +headers.
> +
> +.. _table_rte_flow_action_mpls_ttl_dec:
> +
> +.. table:: MPLS_TTL_DEC
> +
> +   +---------------+---------------------------------------------+
> +   | Field         | Value                                       |
> +
> +===============+=========================================
> ====+
> +   | ``dir_level`` | Specify the level of MPLS header.           |
> +   |               | direction (1b)                              |
> +   |               | 0: match start from outermost.              |
> +   |               | 1: match start from innermost.              |
> +   |               | level: (31b)                                |
> +   |               | 0: outermost or innermost MPLS header       |
> +   |               | 1: next to outmost or innermost MPLS header |
> +   |               | 2: and so on ...                            |
> +   +---------------+---------------------------------------------+

Why not exposing it is as generic operation: increment/decrement for any type of header.
The action struct will receive the flow item type to modify, list of increment/decrement values for each of its fields (+x/-y) along with corresponding mask?

It is true the main use case is TTL decrement for vRouters, however It will save the duplication of the TTL_DEC action below and maybe we will not need to modify the API for future similar actions.


> +
> +Action: ``IP_TTL_DEC``
> +^^^^^^^^^^^^^^^^^^^^^^
> +
> +Decrement IPv4 TTL or IPv6 hop limit field and update the IP checksum,
> +only applies to packets that contain specific MPLS headers.
> +
> +.. _table_rte_flow_action_ip_ttl_dec:
> +
> +.. table:: IP_TTL_DEC
> +
> +   +---------------+----------------------------------------------------------+
> +   | Field         | Value                                                    |
> +
> +===============+=========================================
> =================+
> +   | ``dir_level`` | Specify the level of IPv4 or IPv6 header.                |
> +   |               | direction (1b)                                           |
> +   |               | 0: match start from outermost.                           |
> +   |               | 1: match start from innermost.                           |
> +   |               | level: (31b)                                             |
> +   |               | 0: outermost or innermost Ipv4 or IPv6 header            |
> +   |               | 1: next to outmost or innermost MPLS IPv4 or IPv6 header |
> +   |               | 2: and so on ...                                         |
> +
> + +---------------+-----------------------------------------------------
> + -----+
> +
> +Action: ``TTL_COPY_OUT``
> +^^^^^^^^^^^^^^^^^^^^^^^^
> +
> +Copy the TTL from next-to-outermost to outermost header with TTL, copy
> +can be IP to IP, MPLS to MPLS or IP to MPLS, only applies packets that
> +contain required MPLS or IP headers.
> +
> +.. _table_rte_flow_action_ttl_copy_out:
> +
> +.. table:: TTL_COPY_OUT
> +
> +   +---------------+
> +   | Field         |
> +   +===============+
> +   | no properties |
> +   +---------------+

Why only the TTL ? and why only from outermost to next-to-outer-most? 

We can have an action to copy field from flow item to another flow item. 
We will need flow item for src + mask for the field to copy, flow item for dst + mask for the field to set

> +
> +Action: ``TTL_COPY_IN``
> +^^^^^^^^^^^^^^^^^^^^^^^
> +
> +Copy the TTL from outermost to next-to-outermost header with TTL, copy
> +can be IP to IP, MPLS to MPLS or MPLS to IP, only applies packets that
> +contain required MPLS or IP headers.
> +
> +.. _table_rte_flow_action_ttl_copy_in:
> +
> +.. table:: TTL_COPY_IN
> +
> +   +---------------+
> +   | Field         |
> +   +===============+
> +   | no properties |
> +   +---------------+
> +
>  Negative types
>  ~~~~~~~~~~~~~~
> 
> diff --git a/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> index 48688600e..4dd86f10e 100644
> --- a/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> +++ b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> @@ -3442,6 +3442,18 @@ This section lists supported actions and their
> attributes, if any.
>    - ``original {boolean}``: use original VF ID if possible.
>    - ``id {unsigned}``: VF ID to redirect packets to.
> 
> +- ``mpls_ttl_dec``: decrement MPLS TTL.
> +
> +  - ``level``: level of MPLS header.
> +
> +- ``ip_ttl_dec``: decrement IPv4 TTL or IPv6 Hot Limit.
> +
> +  - ``level``: level of IPv4 or IPv6 header.
> +
> +- ``ttl_copy_out``: copy TTL outwards.
> +
> +- ``ttl_copy_in``: copy TTL inwards.
> +
>  Destroying flow rules
>  ~~~~~~~~~~~~~~~~~~~~~
> 
> diff --git a/lib/librte_ether/rte_flow.h b/lib/librte_ether/rte_flow.h index
> 80cf75ff0..96a236945 100644
> --- a/lib/librte_ether/rte_flow.h
> +++ b/lib/librte_ether/rte_flow.h
> @@ -1250,6 +1250,37 @@ enum rte_flow_action_type {
>  	 * See struct rte_flow_action_field_set.
>  	 */
>  	RTE_FLOW_ACTION_TYPE_FIELD_SET,
> +
> +	/**
> +	 * Decrement MPLS TTL, only applies to packets that contain specific
> +	 * MPLS header.
> +	 *
> +	 * See struct rte_flow_action_mpls_ttl_dec.
> +	 */
> +	RTE_FLOW_ACTION_TYPE_MPLS_TTL_DEC,
> +
> +	/**
> +	 * Decrement IPv4 TTL or IPv6 Hop limit field and update the IP
> +	 * checksum, only applies to packets that contain specific IPv4
> +	 * or IPv6 header.
> +	 *
> +	 * See struct rte_flow_action_ip_ttl_dec.
> +	 */
> +	RTE_FLOW_ACTION_TYPE_IP_TTL_DEC,
> +
> +	/**
> +	 * Copy the TTL from next-to-outermost to outermost header with
> TTL,
> +	 * copy can be IP to IP, MPLS to MPLS or IP to MPLS, only applies
> +	 * packets that contain required protocol headers.
> +	 */
> +	RTE_FLOW_ACTION_TYPE_TTL_COPY_OUT,
> +
> +	/**
> +	 * Copy the TTL from outermost to next-to-outermost header with
> TTL,
> +	 * copy can be IP to IP, MPLS to MPLS or MPLS to IP, only applies
> +	 * packets that contain required protocol headers.
> +	 */
> +	RTE_FLOW_ACTION_TYPE_TTL_COPY_IN,
>  };
> 
>  /**
> @@ -1420,6 +1451,52 @@ struct rte_flow_action_field_set {  };
> 
>  /**
> + * RTE_FLOW_ACTION_TYPE_MPLS_TTL_DEC
> + *
> + * Decrement MPLS TTL, only applies to packets that contain specific
> + * MPLS header.
> + */
> +struct rte_flow_action_mpls_ttl_dec {
> +	/**
> +	 * Specify the level of MPLS header.
> +	 *
> +	 * direction (1b)
> +	 * 0: match start from outermost.
> +	 * 1: match start from innermost.
> +	 *
> +	 * level (31b)
> +	 * 0: outermost|innermost MPLS header.
> +	 * 1: next to outermost|innermost MPLS header.
> +	 * 2: and so on ...
> +	 */
> +	uint32_t dir_level;
> +
> +};
> +
> +/**
> + * RTE_FLOW_ACTION_TYPE_IP_TTL_DEC
> + *
> + * Decrement IPv4 TTL or IPv6 hop limit field and update the IP
> + * checksum, only applies to packets that contain specific IPv4
> + * or IPv6 header.
> + */
> +struct rte_flow_action_ip_ttl_dec {
> +	/**
> +	 * Specify the level of IPv4 or IPv6 header.
> +	 *
> +	 * direction (1b)
> +	 * 0: match start from outermost.
> +	 * 1: match start from innermost.
> +	 *
> +	 * level (31b)
> +	 * 0: outermost|innermost IPv4 or IPv6 header.
> +	 * 1: next to outermost|innermost IPv4 or IPv6 header.
> +	 * 2: and so on ...
> +	 */
> +	uint32_t dir_level;
> +};
> +
> +/**
>   * Definition of a single action.
>   *
>   * A list of actions is terminated by a END action.
> --
> 2.13.6