[dpdk-dev] [PATCH v2 1/5] ethdev: update modify field flow action

[Viacheslav Ovsiienko]

The generic modify field flow action introduced in [1] has
some issues related to the immediate source operand:

  - immediate source can be presented either as an unsigned
    64-bit integer or pointer to data pattern in memory.
    There was no explicit pointer field defined in the union.

  - the byte ordering for 64-bit integer was not specified.
    Many fields have shorter lengths and byte ordering
    is crucial.

  - how the bit offset is applied to the immediate source
    field was not defined and documented.

  - 64-bit integer size is not enough to provide IPv6
    addresses.

In order to cover the issues and exclude any ambiguities
the following is done:

  - introduce the explicit pointer field
    in rte_flow_action_modify_data structure

  - replace the 64-bit unsigned integer with 16-byte array

  - update the modify field flow action documentation

[1] commit 73b68f4c54a0 ("ethdev: introduce generic modify flow action")

Signed-off-by: Viacheslav Ovsiienko <viacheslavo at nvidia.com>
---
 doc/guides/prog_guide/rte_flow.rst     | 16 ++++++++++++++++
 doc/guides/rel_notes/release_21_11.rst |  9 +++++++++
 lib/ethdev/rte_flow.h                  | 17 ++++++++++++++---
 3 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/doc/guides/prog_guide/rte_flow.rst b/doc/guides/prog_guide/rte_flow.rst
index 2b42d5ec8c..1ceecb399f 100644
--- a/doc/guides/prog_guide/rte_flow.rst
+++ b/doc/guides/prog_guide/rte_flow.rst
@@ -2835,6 +2835,22 @@ a packet to any other part of it.
 ``value`` sets an immediate value to be used as a source or points to a
 location of the value in memory. It is used instead of ``level`` and ``offset``
 for ``RTE_FLOW_FIELD_VALUE`` and ``RTE_FLOW_FIELD_POINTER`` respectively.
+The data in memory should be presented exactly in the same byte order and
+length as in the relevant flow item, i.e. data for field with type
+RTE_FLOW_FIELD_MAC_DST should follow the conventions of dst field
+in rte_flow_item_eth structure, with type RTE_FLOW_FIELD_IPV6_SRC -
+rte_flow_item_ipv6 conventions, and so on. If the field size is large than
+16 bytes the pattern can be provided as pointer only.
+
+The bitfield extracted from the memory being applied as second operation
+parameter is defined by action width and by the destination field offset.
+Application should provide the data in immediate value memory (either as
+buffer or by pointer) exactly as item field without any applied explicit offset,
+and destination packet field (with specified width and bit offset) will be
+replaced by immediate source bits from the same bit offset. For example,
+to replace the third byte of MAC address with value 0x85, application should
+specify destination width as 8, destination width as 16, and provide immediate
+value as sequence of bytes {xxx, xxx, 0x85, xxx, xxx, xxx}.
 
 .. _table_rte_flow_action_modify_field:
 
diff --git a/doc/guides/rel_notes/release_21_11.rst b/doc/guides/rel_notes/release_21_11.rst
index dfc2cbdeed..41a087d7c1 100644
--- a/doc/guides/rel_notes/release_21_11.rst
+++ b/doc/guides/rel_notes/release_21_11.rst
@@ -187,6 +187,13 @@ API Changes
   the crypto/security operation. This field will be used to communicate
   events such as soft expiry with IPsec in lookaside mode.
 
+* ethdev: ``rte_flow_action_modify_data`` structure udpdated, immediate data
+  array is extended, data pointer field is explicitly added to union, the
+  action behavior is defined in more strict fashion and documentation updated.
+  The immediate value behavior has been changed, the entire immediate field
+  should be provided, and offset for immediate source bitfield is assigned
+  from destination one.
+
 
 ABI Changes
 -----------
@@ -222,6 +229,8 @@ ABI Changes
   ``rte_security_ipsec_xform`` to allow applications to configure SA soft
   and hard expiry limits. Limits can be either in number of packets or bytes.
 
+* ethdev: ``rte_flow_action_modify_data`` structure udpdated.
+
 
 Known Issues
 ------------
diff --git a/lib/ethdev/rte_flow.h b/lib/ethdev/rte_flow.h
index 7b1ed7f110..953924d42b 100644
--- a/lib/ethdev/rte_flow.h
+++ b/lib/ethdev/rte_flow.h
@@ -3204,6 +3204,9 @@ enum rte_flow_field_id {
 };
 
 /**
+ * @warning
+ * @b EXPERIMENTAL: this structure may change without prior notice
+ *
  * Field description for MODIFY_FIELD action.
  */
 struct rte_flow_action_modify_data {
@@ -3217,10 +3220,18 @@ struct rte_flow_action_modify_data {
 			uint32_t offset;
 		};
 		/**
-		 * Immediate value for RTE_FLOW_FIELD_VALUE or
-		 * memory address for RTE_FLOW_FIELD_POINTER.
+		 * Immediate value for RTE_FLOW_FIELD_VALUE, presented in the
+		 * same byte order and length as in relevant rte_flow_item_xxx.
+		 * The immediate source bitfield offset is inherited from
+		 * the destination's one.
 		 */
-		uint64_t value;
+		uint8_t value[16];
+		/*
+		 * Memory address for RTE_FLOW_FIELD_POINTER, memory layout
+		 * should be the same as for relevant field in the
+		 * rte_flow_item_xxx structure.
+		 */
+		void *pvalue;
 	};
 };
 
-- 
2.18.1