[v5,1/2] ethdev: introduce conntrack flow action and item

diff --git a/doc/guides/prog_guide/rte_flow.rst b/doc/guides/prog_guide/rte_flow.rst
index 4b54588995..5f6129f799 100644
--- a/doc/guides/prog_guide/rte_flow.rst
+++ b/doc/guides/prog_guide/rte_flow.rst
@@ -1398,6 +1398,14 @@  Matches a eCPRI header.
 - ``hdr``: eCPRI header definition (``rte_ecpri.h``).
 - Default ``mask`` matches nothing, for all eCPRI messages.
 
+Item: ``CONNTRACK``
+^^^^^^^^^^^^^^^^^^^
+
+Matches a conntrack state after conntrack action.
+
+- ``flags``: conntrack packet state flags.
+- Default ``mask`` matches all state bits.
+
 Actions
 ~~~~~~~
 
@@ -2842,6 +2850,116 @@  for ``RTE_FLOW_FIELD_VALUE`` and ``RTE_FLOW_FIELD_POINTER`` respectively.
    | ``value``     | immediate value or a pointer to this value               |
    +---------------+----------------------------------------------------------+
 
+Action: ``CONNTRACK``
+^^^^^^^^^^^^^^^^^^^^^
+
+Create a conntrack (connection tracking) context with the provided information.
+
+In stateful session like TCP, the conntrack action provides the ability to
+examine every packet of this connection and associate the state to every
+packet. It will help to realize the stateful offload of connections with little
+software participation. For example, the packets with invalid state may be
+handled by the software. The control packets could be handled in the hardware.
+The software just need to query the state of a connection when needed, and then
+decide how to handle the flow rules and conntrack context.
+
+A conntrack context should be created via ``rte_flow_action_handle_create()``
+before using. Then the handle with ``INDIRECT`` type is used for a flow rule
+creation. If a flow rule with an opposite direction needs to be created, the
+``rte_flow_action_handle_update()`` should be used to modify the direction.
+
+Not all the fields of the ``struct rte_flow_action_conntrack`` will be used
+for a conntrack context creating, depending on the HW, and they should be
+in host byte order. PMD should convert them into network byte order when
+needed by the HW.
+
+The ``struct rte_flow_modify_conntrack`` should be used for an updating.
+
+The current conntrack context information could be queried via the
+``rte_flow_action_handle_query()`` interface.
+
+.. _table_rte_flow_action_conntrack:
+
+.. table:: CONNTRACK
+
+   +--------------------------+-------------------------------------------------------------+
+   | Field                    | Value                                                       |
+   +==========================+=============================================================+
+   | ``peer_port``            | peer port number                                            |
+   +--------------------------+-------------------------------------------------------------+
+   | ``is_original_dir``      | direction of this connection for creating flow rule         |
+   +--------------------------+-------------------------------------------------------------+
+   | ``enable``               | enable the conntrack context                                |
+   +--------------------------+-------------------------------------------------------------+
+   | ``live_connection``      | one ack was seen for this connection                        |
+   +--------------------------+-------------------------------------------------------------+
+   | ``selective_ack``        | SACK enabled                                                |
+   +--------------------------+-------------------------------------------------------------+
+   | ``challenge_ack_passed`` | a challenge ack has passed                                  |
+   +--------------------------+-------------------------------------------------------------+
+   | ``last_direction``       | direction of the last passed packet                         |
+   +--------------------------+-------------------------------------------------------------+
+   | ``liberal_mode``         | only report state change                                    |
+   +--------------------------+-------------------------------------------------------------+
+   | ``state``                | current state                                               |
+   +--------------------------+-------------------------------------------------------------+
+   | ``max_ack_window``       | maximal window scaling factor                               |
+   +--------------------------+-------------------------------------------------------------+
+   | ``retransmission_limit`` | maximal retransmission times                                |
+   +--------------------------+-------------------------------------------------------------+
+   | ``original_dir``         | TCP parameters of the original direction                    |
+   +--------------------------+-------------------------------------------------------------+
+   | ``reply_dir``            | TCP parameters of the reply direction                       |
+   +--------------------------+-------------------------------------------------------------+
+   | ``last_window``          | window size of the last passed packet                       |
+   +--------------------------+-------------------------------------------------------------+
+   | ``last_seq``             | sequence number of the last passed packet                   |
+   +--------------------------+-------------------------------------------------------------+
+   | ``last_ack``             | acknowledgment number the last passed packet                |
+   +--------------------------+-------------------------------------------------------------+
+   | ``last_end``             | sum of ack number and length of the last passed packet      |
+   +--------------------------+-------------------------------------------------------------+
+
+.. _table_rte_flow_tcp_dir_param:
+
+.. table:: configuration parameters for each direction
+
+   +---------------------+---------------------------------------------------------+
+   | Field               | Value                                                   |
+   +=====================+=========================================================+
+   | ``scale``           | TCP window scaling factor                               |
+   +---------------------+---------------------------------------------------------+
+   | ``close_initiated`` | FIN sent from this direction                            |
+   +---------------------+---------------------------------------------------------+
+   | ``last_ack_seen``   | an ACK packet received                                  |
+   +---------------------+---------------------------------------------------------+
+   | ``data_unacked``    | unacknowledged data for packets from this direction     |
+   +---------------------+---------------------------------------------------------+
+   | ``sent_end``        | max{seq + len} seen in sent packets                     |
+   +---------------------+---------------------------------------------------------+
+   | ``reply_end``       | max{sack + max{win, 1}} seen in reply packets           |
+   +---------------------+---------------------------------------------------------+
+   | ``max_win``         | max{max{win, 1}} + {sack - ack} seen in sent packets    |
+   +---------------------+---------------------------------------------------------+
+   | ``max_ack``         | max{ack} + seen in sent packets                         |
+   +---------------------+---------------------------------------------------------+
+
+.. _table_rte_flow_modify_conntrack:
+
+.. table:: update a conntrack context
+
+   +----------------+-------------------------------------------------+
+   | Field          | Value                                           |
+   +================+=================================================+
+   | ``new_ct``     | new conntrack information                       |
+   +----------------+-------------------------------------------------+
+   | ``direction``  | direction will be updated                       |
+   +----------------+-------------------------------------------------+
+   | ``state``      | other fields except direction will be updated   |
+   +----------------+-------------------------------------------------+
+   | ``reserved``   | reserved bits                                   |
+   +----------------+-------------------------------------------------+
+
 Negative types
 ~~~~~~~~~~~~~~
 
diff --git a/doc/guides/rel_notes/release_21_05.rst b/doc/guides/rel_notes/release_21_05.rst
index 8913dd4f9c..a5e2a8e503 100644
--- a/doc/guides/rel_notes/release_21_05.rst
+++ b/doc/guides/rel_notes/release_21_05.rst
@@ -87,6 +87,10 @@  New Features
   to support metering traffic by packet per second (PPS),
   in addition to the initial bytes per second (BPS) mode (value 0).
 
+* **Added TCP connection tracking offload in flow API.**
+
+  * Added conntrack item and action for stateful connection offload.
+
 * **Updated Arkville PMD driver.**
 
   Updated Arkville net driver with new features and improvements, including:
diff --git a/lib/librte_ethdev/rte_flow.c b/lib/librte_ethdev/rte_flow.c
index 0d2610b7c4..c7c7108933 100644
--- a/lib/librte_ethdev/rte_flow.c
+++ b/lib/librte_ethdev/rte_flow.c
@@ -98,6 +98,7 @@  static const struct rte_flow_desc_data rte_flow_desc_item[] = {
 	MK_FLOW_ITEM(PFCP, sizeof(struct rte_flow_item_pfcp)),
 	MK_FLOW_ITEM(ECPRI, sizeof(struct rte_flow_item_ecpri)),
 	MK_FLOW_ITEM(GENEVE_OPT, sizeof(struct rte_flow_item_geneve_opt)),
+	MK_FLOW_ITEM(CONNTRACK, sizeof(uint32_t)),
 };
 
 /** Generate flow_action[] entry. */
@@ -186,6 +187,7 @@  static const struct rte_flow_desc_data rte_flow_desc_action[] = {
 	 * indirect action handle.
 	 */
 	MK_FLOW_ACTION(INDIRECT, 0),
+	MK_FLOW_ACTION(CONNTRACK, sizeof(struct rte_flow_action_conntrack)),
 };
 
 int
diff --git a/lib/librte_ethdev/rte_flow.h b/lib/librte_ethdev/rte_flow.h
index 0447d36002..dae16b3433 100644
--- a/lib/librte_ethdev/rte_flow.h
+++ b/lib/librte_ethdev/rte_flow.h
@@ -30,6 +30,7 @@ 
 #include <rte_esp.h>
 #include <rte_higig.h>
 #include <rte_ecpri.h>
+#include <rte_bitops.h>
 #include <rte_mbuf.h>
 #include <rte_mbuf_dyn.h>
 
@@ -551,6 +552,15 @@  enum rte_flow_item_type {
 	 * See struct rte_flow_item_geneve_opt
 	 */
 	RTE_FLOW_ITEM_TYPE_GENEVE_OPT,
+
+	/**
+	 * [META]
+	 *
+	 * Matches conntrack state.
+	 *
+	 * @see struct rte_flow_item_conntrack.
+	 */
+	RTE_FLOW_ITEM_TYPE_CONNTRACK,
 };
 
 /**
@@ -1685,6 +1695,51 @@  rte_flow_item_geneve_opt_mask = {
 };
 #endif
 
+/**
+ * The packet is valid after conntrack checking.
+ */
+#define RTE_FLOW_CONNTRACK_PKT_STATE_VALID RTE_BIT32(0)
+/**
+ * The state of the connection is changed.
+ */
+#define RTE_FLOW_CONNTRACK_PKT_STATE_CHANGED RTE_BIT32(1)
+/**
+ * Error is detected on this packet for this connection and
+ * an invalid state is set.
+ */
+#define RTE_FLOW_CONNTRACK_PKT_STATE_INVALID RTE_BIT32(2)
+/**
+ * The HW connection tracking module is disabled.
+ * It can be due to application command or an invalid state.
+ */
+#define RTE_FLOW_CONNTRACK_PKT_STATE_DISABLED RTE_BIT32(3)
+/**
+ * The packet contains some bad field(s) and cannot continue
+ * with the conntrack module checking.
+ */
+#define RTE_FLOW_CONNTRACK_PKT_STATE_BAD RTE_BIT32(4)
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this structure may change without prior notice
+ *
+ * RTE_FLOW_ITEM_TYPE_CONNTRACK
+ *
+ * Matches the state of a packet after it passed the connection tracking
+ * examination. The state is a bitmap of one RTE_FLOW_CONNTRACK_PKT_STATE*
+ * or a reasonable combination of these bits.
+ */
+struct rte_flow_item_conntrack {
+	uint32_t flags;
+};
+
+/** Default mask for RTE_FLOW_ITEM_TYPE_CONNTRACK. */
+#ifndef __cplusplus
+static const struct rte_flow_item_conntrack rte_flow_item_conntrack_mask = {
+	.flags = 0xffffffff,
+};
+#endif
+
 /**
  * Matching pattern item definition.
  *
@@ -2278,6 +2333,15 @@  enum rte_flow_action_type {
 	 * or different ethdev ports.
 	 */
 	RTE_FLOW_ACTION_TYPE_INDIRECT,
+
+	/**
+	 * [META]
+	 *
+	 * Enable tracking a TCP connection state.
+	 *
+	 * @see struct rte_flow_action_conntrack.
+	 */
+	RTE_FLOW_ACTION_TYPE_CONNTRACK,
 };
 
 /**
@@ -2876,6 +2940,154 @@  struct rte_flow_action_set_dscp {
  */
 struct rte_flow_action_handle;
 
+/**
+ * The state of a TCP connection.
+ */
+enum rte_flow_conntrack_state {
+	/** SYN-ACK packet was seen. */
+	RTE_FLOW_CONNTRACK_STATE_SYN_RECV,
+	/** 3-way handshake was done. */
+	RTE_FLOW_CONNTRACK_STATE_ESTABLISHED,
+	/** First FIN packet was received to close the connection. */
+	RTE_FLOW_CONNTRACK_STATE_FIN_WAIT,
+	/** First FIN was ACKed. */
+	RTE_FLOW_CONNTRACK_STATE_CLOSE_WAIT,
+	/** Second FIN was received, waiting for the last ACK. */
+	RTE_FLOW_CONNTRACK_STATE_LAST_ACK,
+	/** Second FIN was ACKed, connection was closed. */
+	RTE_FLOW_CONNTRACK_STATE_TIME_WAIT,
+};
+
+/**
+ * The last passed TCP packet flags of a connection.
+ */
+enum rte_flow_conntrack_tcp_last_index {
+	RTE_FLOW_CONNTRACK_FLAG_NONE = 0, /**< No Flag. */
+	RTE_FLOW_CONNTRACK_FLAG_SYN = RTE_BIT32(0), /**< With SYN flag. */
+	RTE_FLOW_CONNTRACK_FLAG_SYNACK = RTE_BIT32(1), /**< With SYNACK flag. */
+	RTE_FLOW_CONNTRACK_FLAG_FIN = RTE_BIT32(2), /**< With FIN flag. */
+	RTE_FLOW_CONNTRACK_FLAG_ACK = RTE_BIT32(3), /**< With ACK flag. */
+	RTE_FLOW_CONNTRACK_FLAG_RST = RTE_BIT32(4), /**< With RST flag. */
+};
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this structure may change without prior notice
+ *
+ * Configuration parameters for each direction of a TCP connection.
+ * All fields should be in host byte order.
+ * If needed, driver should convert all fields to network byte order
+ * if HW needs them in that way.
+ */
+struct rte_flow_tcp_dir_param {
+	/** TCP window scaling factor, 0xF to disable. */
+	uint32_t scale:4;
+	/** The FIN was sent by this direction. */
+	uint32_t close_initiated:1;
+	/** An ACK packet has been received by this side. */
+	uint32_t last_ack_seen:1;
+	/**
+	 * If set, it indicates that there is unacknowledged data for the
+	 * packets sent from this direction.
+	 */
+	uint32_t data_unacked:1;
+	/**
+	 * Maximal value of sequence + payload length in sent
+	 * packets (next ACK from the opposite direction).
+	 */
+	uint32_t sent_end;
+	/**
+	 * Maximal value of (ACK + window size) in received packet + length
+	 * over sent packet (maximal sequence could be sent).
+	 */
+	uint32_t reply_end;
+	/** Maximal value of actual window size in sent packets. */
+	uint32_t max_win;
+	/** Maximal value of ACK in sent packets. */
+	uint32_t max_ack;
+};
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this structure may change without prior notice
+ *
+ * RTE_FLOW_ACTION_TYPE_CONNTRACK
+ *
+ * Configuration and initial state for the connection tracking module.
+ * This structure could be used for both setting and query.
+ * All fields should be in host byte order.
+ */
+struct rte_flow_action_conntrack {
+	/** The peer port number, can be the same port. */
+	uint16_t peer_port;
+	/**
+	 * Direction of this connection when creating a flow rule, the
+	 * value only affects the creation of subsequent flow rules.
+	 */
+	uint32_t is_original_dir:1;
+	/**
+	 * Enable / disable the conntrack HW module. When disabled, the
+	 * result will always be RTE_FLOW_CONNTRACK_FLAG_DISABLED.
+	 * In this state the HW will act as passthrough.
+	 * It only affects this conntrack object in the HW without any effect
+	 * to the other objects.
+	 */
+	uint32_t enable:1;
+	/** At least one ack was seen after the connection was established. */
+	uint32_t live_connection:1;
+	/** Enable selective ACK on this connection. */
+	uint32_t selective_ack:1;
+	/** A challenge ack has passed. */
+	uint32_t challenge_ack_passed:1;
+	/**
+	 * 1: The last packet is seen from the original direction.
+	 * 0: The last packet is seen from the reply direction.
+	 */
+	uint32_t last_direction:1;
+	/** No TCP check will be done except the state change. */
+	uint32_t liberal_mode:1;
+	/**<The current state of this connection. */
+	enum rte_flow_conntrack_state state;
+	/** Scaling factor for maximal allowed ACK window. */
+	uint8_t max_ack_window;
+	/** Maximal allowed number of retransmission times. */
+	uint8_t retransmission_limit;
+	/** TCP parameters of the original direction. */
+	struct rte_flow_tcp_dir_param original_dir;
+	/** TCP parameters of the reply direction. */
+	struct rte_flow_tcp_dir_param reply_dir;
+	/** The window value of the last packet passed this conntrack. */
+	uint16_t last_window;
+	enum rte_flow_conntrack_tcp_last_index last_index;
+	/** The sequence of the last packet passed this conntrack. */
+	uint32_t last_seq;
+	/** The acknowledgment of the last packet passed this conntrack. */
+	uint32_t last_ack;
+	/**
+	 * The total value ACK + payload length of the last packet
+	 * passed this conntrack.
+	 */
+	uint32_t last_end;
+};
+
+/**
+ * RTE_FLOW_ACTION_TYPE_CONNTRACK
+ *
+ * Wrapper structure for the context update interface.
+ * Ports cannot support updating, and the only valid solution is to
+ * destroy the old context and create a new one instead.
+ */
+struct rte_flow_modify_conntrack {
+	/** New connection tracking parameters to be updated. */
+	struct rte_flow_action_conntrack new_ct;
+	/** The direction field will be updated. */
+	uint32_t direction:1;
+	/** All the other fields except direction will be updated. */
+	uint32_t state:1;
+	/** Reserved bits for the future usage. */
+	uint32_t reserved:30;
+};
+
 /**
  * Field IDs for MODIFY_FIELD action.
  */