[PATCH v2 5/5] ethdev: add MPLS header modification support

[Ori Kam]

Hi Michael,

> -----Original Message-----
> From: Michael Baum <michaelba at nvidia.com>
> Sent: Thursday, May 18, 2023 8:40 PM
> 
> Add support for MPLS modify header using "RTE_FLOW_FIELD_MPLS" id.
> 
> Since MPLS heaser might appear more the one time in inner/outer/tunnel,
> a new field was added to "rte_flow_action_modify_data" structure in
> addition to "level" field.
> The "tag_index" field is the index of the header inside encapsulation
> level. It is used for modify multiple MPLS headers in same encapsulation
> level.
> 
> This addition enables to modify multiple VLAN headers too, so the
> description of "RTE_FLOW_FIELD_VLAN_XXXX" was updated.
> 
> Signed-off-by: Michael Baum <michaelba at nvidia.com>
> ---

[Snip]

> diff --git a/doc/guides/prog_guide/rte_flow.rst
> b/doc/guides/prog_guide/rte_flow.rst
> index ec812de335..591e43b5ac 100644
> --- a/doc/guides/prog_guide/rte_flow.rst
> +++ b/doc/guides/prog_guide/rte_flow.rst
> @@ -2925,8 +2925,7 @@ See ``enum rte_flow_field_id`` for the list of
> supported fields.
> 
>  ``width`` defines a number of bits to use from ``src`` field.
> 
> -``level`` is used to access any packet field on any encapsulation level
> -as well as any tag element in the tag array:
> +``level`` is used to access any packet field on any encapsulation level:
> 
>  - ``0`` means the default behaviour. Depending on the packet type,
>    it can mean outermost, innermost or anything in between.
> @@ -2934,8 +2933,9 @@ as well as any tag element in the tag array:
>  - ``2`` and subsequent values requests access to the specified packet
>    encapsulation level, from outermost to innermost (lower to higher values).
> 
> -For the tag array (in case of multiple tags are supported and present)
> -``level`` translates directly into the array index.
> +``tag_index`` is the index of the header inside encapsulation level.
> +It is used for modify either ``VLAN`` or ``MPLS`` or ``TAG`` headers which
> +multiple of them might be supported in same encapsulation level.
> 
This is an API change and must be documented as such in the release notes.
I suggest to avoid breaking working apps that it will be documented that
for this release when using tag the PMD will look at level and tag_id
If both equal to 0 --> the requested tag is zero
If tag_id == 0 and level != 0 PMD will selected the tag based on level, but will output a warning
If tag_id != 0 and level == 0 PMD will select the tag based on the tag_id

>  ``type`` is used to specify (along with ``class_id``) the Geneve option which
>  is being modified.
> @@ -3011,7 +3011,9 @@ and provide immediate value 0xXXXX85XX.
> 
> +=================+============================================
> ==============+
>     | ``field``       | ID: packet field, mark, meta, tag, immediate, pointer    |
>     +-----------------+----------------------------------------------------------+
> -   | ``level``       | encapsulation level of a packet field or tag array index |
> +   | ``level``       | encapsulation level of a packet field                    |
> +   +-----------------+----------------------------------------------------------+
> +   | ``tag_index``   | tag index inside encapsulation level                     |
>     +-----------------+----------------------------------------------------------+
>     | ``type``        | geneve option type                                       |
>     +-----------------+----------------------------------------------------------+
> diff --git a/lib/ethdev/rte_flow.h b/lib/ethdev/rte_flow.h
> index f30d4b033f..34e536d662 100644
> --- a/lib/ethdev/rte_flow.h
> +++ b/lib/ethdev/rte_flow.h
> @@ -3740,8 +3740,8 @@ enum rte_flow_field_id {
>  	RTE_FLOW_FIELD_START = 0,	/**< Start of a packet. */
>  	RTE_FLOW_FIELD_MAC_DST,		/**< Destination MAC
> Address. */
>  	RTE_FLOW_FIELD_MAC_SRC,		/**< Source MAC Address. */
> -	RTE_FLOW_FIELD_VLAN_TYPE,	/**< 802.1Q Tag Identifier. */
> -	RTE_FLOW_FIELD_VLAN_ID,		/**< 802.1Q VLAN Identifier.
> */
> +	RTE_FLOW_FIELD_VLAN_TYPE,	/**< VLAN Tag Identifier. */
> +	RTE_FLOW_FIELD_VLAN_ID,		/**< VLAN Identifier. */
>  	RTE_FLOW_FIELD_MAC_TYPE,	/**< EtherType. */
>  	RTE_FLOW_FIELD_IPV4_DSCP,	/**< IPv4 DSCP. */
>  	RTE_FLOW_FIELD_IPV4_TTL,	/**< IPv4 Time To Live. */
> @@ -3775,7 +3775,8 @@ enum rte_flow_field_id {
>  	RTE_FLOW_FIELD_HASH_RESULT,	/**< Hash result. */
>  	RTE_FLOW_FIELD_GENEVE_OPT_TYPE,	/**< GENEVE option type */
>  	RTE_FLOW_FIELD_GENEVE_OPT_CLASS,/**< GENEVE option class */
> -	RTE_FLOW_FIELD_GENEVE_OPT_DATA	/**< GENEVE option data */
> +	RTE_FLOW_FIELD_GENEVE_OPT_DATA,	/**< GENEVE option
> data */
> +	RTE_FLOW_FIELD_MPLS		/**< MPLS header. */
>  };
> 
>  /**
> @@ -3789,7 +3790,7 @@ struct rte_flow_action_modify_data {
>  	RTE_STD_C11
>  	union {
>  		struct {
> -			/** Encapsulation level or tag index or flex item
> handle. */
> +			/** Encapsulation level and tag index or flex item
> handle. */
>  			union {
>  				struct {
>  					/**
> @@ -3820,20 +3821,36 @@ struct rte_flow_action_modify_data {
>  					 *
>  					 * Values other than @p 0 are not
>  					 * necessarily supported.
> +					 *
> +					 * @note that for MPLS field,
> +					 * encapsulation level also include
> +					 * tunnel since MPLS may appear in
> +					 * outer, inner or tunnel.
>  					 */
>  					uint8_t level;
> -					/**
> -					 * Geneve option type. relevant only
> -					 * for
> RTE_FLOW_FIELD_GENEVE_OPT_XXXX
> -					 * modification type.
> -					 */
> -					uint8_t type;
> -					/**
> -					 * Geneve option class. relevant only
> -					 * for
> RTE_FLOW_FIELD_GENEVE_OPT_XXXX
> -					 * modification type.
> -					 */
> -					rte_be16_t class_id;
> +					union {
> +						/**
> +						 * Tag index array inside
> +						 * encapsulation level.
> +						 */

I think it is also worth noting that this is used also for VLAN and MPLS.

> +						uint8_t tag_index;
> +						/**
> +						 * Geneve option identifier.
> +						 * relevant only for
> +						 *
> RTE_FLOW_FIELD_GENEVE_OPT_XXXX
> +						 * modification type.
> +						 */
> +						struct {
> +							/**
> +							 * Geneve option
> type.
> +							 */
> +							uint8_t type;
> +							/**
> +							 * Geneve option
> class.
> +							 */
> +							rte_be16_t class_id;
> +						};
> +					};
>  				};
>  				struct rte_flow_item_flex_handle
> *flex_handle;
>  			};
> --
> 2.25.1