[dpdk-dev] [RFC v2] ethdev: add action to swap source and destination MAC to flow API

[Rahul Lakkireddy]

From: Shagun Agrawal <shaguna at chelsio.com>

This action is useful for offloading loopback mode, where the hardware
will swap source and destination MAC addresses in the outermost Ethernet
header before looping back the packet. This action can be used in
conjunction with other rewrite actions to achieve MAC layer transparent
NAT where the MAC addresses are swapped before either the source or
destination MAC address is rewritten and NAT is performed.

Must be used with a valid RTE_FLOW_ITEM_TYPE_ETH flow pattern item.
Otherwise, RTE_FLOW_ERROR_TYPE_ACTION error should be returned by the
PMDs.

Signed-off-by: Shagun Agrawal <shaguna at chelsio.com>
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy at chelsio.com>
---
v2:
- Updated all comments and doc to indicate outermost Ethernet header's
  source and destination MAC addresses are swapped and that a valid
  RTE_FLOW_ITEM_TYPE_ETH must be specified. Otherwise,
  RTE_FLOW_ERROR_TYPE_ACTION error should be returned by the PMDs.

 app/test-pmd/cmdline_flow.c                 | 10 ++++++++++
 app/test-pmd/config.c                       |  1 +
 doc/guides/prog_guide/rte_flow.rst          | 19 +++++++++++++++++++
 doc/guides/testpmd_app_ug/testpmd_funcs.rst |  3 +++
 lib/librte_ethdev/rte_flow.c                |  1 +
 lib/librte_ethdev/rte_flow.h                | 11 +++++++++++
 6 files changed, 45 insertions(+)

diff --git a/app/test-pmd/cmdline_flow.c b/app/test-pmd/cmdline_flow.c
index f9260600e..196c76de1 100644
--- a/app/test-pmd/cmdline_flow.c
+++ b/app/test-pmd/cmdline_flow.c
@@ -243,6 +243,7 @@ enum index {
 	ACTION_VXLAN_DECAP,
 	ACTION_NVGRE_ENCAP,
 	ACTION_NVGRE_DECAP,
+	ACTION_MAC_SWAP,
 };
 
 /** Maximum size for pattern in struct rte_flow_item_raw. */
@@ -816,6 +817,7 @@ static const enum index next_action[] = {
 	ACTION_VXLAN_DECAP,
 	ACTION_NVGRE_ENCAP,
 	ACTION_NVGRE_DECAP,
+	ACTION_MAC_SWAP,
 	ZERO,
 };
 
@@ -2470,6 +2472,14 @@ static const struct token token_list[] = {
 		.next = NEXT(NEXT_ENTRY(ACTION_NEXT)),
 		.call = parse_vc,
 	},
+	[ACTION_MAC_SWAP] = {
+		.name = "mac_swap",
+		.help = "Swap the source and destination MAC addresses"
+			" in the outermost Ethernet header",
+		.priv = PRIV_ACTION(MAC_SWAP, 0),
+		.next = NEXT(NEXT_ENTRY(ACTION_NEXT)),
+		.call = parse_vc,
+	},
 };
 
 /** Remove and return last entry from argument stack. */
diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c
index 14ccd6864..b7393967a 100644
--- a/app/test-pmd/config.c
+++ b/app/test-pmd/config.c
@@ -1153,6 +1153,7 @@ static const struct {
 		       sizeof(struct rte_flow_action_of_pop_mpls)),
 	MK_FLOW_ACTION(OF_PUSH_MPLS,
 		       sizeof(struct rte_flow_action_of_push_mpls)),
+	MK_FLOW_ACTION(MAC_SWAP, 0),
 };
 
 /** Compute storage space needed by action configuration and copy it. */
diff --git a/doc/guides/prog_guide/rte_flow.rst b/doc/guides/prog_guide/rte_flow.rst
index b305a72a5..d09806d38 100644
--- a/doc/guides/prog_guide/rte_flow.rst
+++ b/doc/guides/prog_guide/rte_flow.rst
@@ -2076,6 +2076,25 @@ RTE_FLOW_ERROR_TYPE_ACTION error should be returned.
 
 This action modifies the payload of matched flows.
 
+Action: ``MAC_SWAP``
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Swap the source and destination MAC addresses in the outermost Ethernet
+header.
+
+It must be used with a valid RTE_FLOW_ITEM_TYPE_ETH flow pattern item.
+Otherwise, RTE_FLOW_ERROR_TYPE_ACTION error will be returned.
+
+.. _table_rte_flow_action_mac_swap:
+
+.. table:: MAC_SWAP
+
+   +---------------+
+   | 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 dde205a2b..f32c6d11e 100644
--- a/doc/guides/testpmd_app_ug/testpmd_funcs.rst
+++ b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
@@ -3697,6 +3697,9 @@ This section lists supported actions and their attributes, if any.
 - ``nvgre_decap``: Performs a decapsulation action by stripping all headers of
   the NVGRE tunnel network overlay from the matched flow.
 
+- ``mac_swap``: Swap the source and destination MAC addresses in the outermost
+  Ethernet header.
+
 Destroying flow rules
 ~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/lib/librte_ethdev/rte_flow.c b/lib/librte_ethdev/rte_flow.c
index cff4b5209..04b0b40ea 100644
--- a/lib/librte_ethdev/rte_flow.c
+++ b/lib/librte_ethdev/rte_flow.c
@@ -109,6 +109,7 @@ static const struct rte_flow_desc_data rte_flow_desc_action[] = {
 		       sizeof(struct rte_flow_action_of_pop_mpls)),
 	MK_FLOW_ACTION(OF_PUSH_MPLS,
 		       sizeof(struct rte_flow_action_of_push_mpls)),
+	MK_FLOW_ACTION(MAC_SWAP, 0),
 };
 
 static int
diff --git a/lib/librte_ethdev/rte_flow.h b/lib/librte_ethdev/rte_flow.h
index f8ba71cdb..c743f818e 100644
--- a/lib/librte_ethdev/rte_flow.h
+++ b/lib/librte_ethdev/rte_flow.h
@@ -1505,6 +1505,17 @@ enum rte_flow_action_type {
 	 * error.
 	 */
 	RTE_FLOW_ACTION_TYPE_NVGRE_DECAP,
+
+	/**
+	 * Swap the source and destination MAC addresses in the outermost
+	 * Ethernet header.
+	 *
+	 * If flow pattern does not define a valid RTE_FLOW_ITEM_TYPE_ETH,
+	 * then the PMD should return a RTE_FLOW_ERROR_TYPE_ACTION error.
+	 *
+	 * No associated configuration structure.
+	 */
+	RTE_FLOW_ACTION_TYPE_MAC_SWAP,
 };
 
 /**
-- 
2.14.1