[dpdk-dev] [PATCH v5] net: introduce IPv4 ihl and version fields

[Gregory Etelson <getelson@nvidia.com>]

RTE IPv4 header definition combines the `version' and `ihl'  fields
into a single structure member.
This patch introduces dedicated structure members for both `version'
and `ihl' IPv4 fields. Separated header fields definitions allow to
create simplified code to match on the IHL value in a flow rule.
The original `version_ihl' structure member is kept for backward
compatibility.
The patch implements one of 2 announced changes to the
IPv4 header.
IPv4 header encodes fragment information into 16 bits field.
3 bits hold flags and remaining 13 bits are for fragment offset.
13 bits bit-field cannot be defined both for big and little endian
systems.

Signed-off-by: Gregory Etelson <getelson@nvidia.com>

Acked-by: Olivier Matz <olivier.matz@6wind.com>

---
v2: Add dependency.
v3: Add comments.
v4: Update release notes.
v5: Remove deprecation notice.
    Update the patch comment.
---
 app/test/test_flow_classify.c          |  8 ++++----
 doc/guides/rel_notes/deprecation.rst   |  6 ------
 doc/guides/rel_notes/release_21_11.rst |  3 +++
 lib/net/rte_ip.h                       | 16 +++++++++++++++-
 4 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/app/test/test_flow_classify.c b/app/test/test_flow_classify.c
index 951606f248..4f64be5357 100644
--- a/app/test/test_flow_classify.c
+++ b/app/test/test_flow_classify.c
@@ -95,7 +95,7 @@ static struct rte_acl_field_def ipv4_defs[NUM_FIELDS_IPV4] = {
  *  dst mask 255.255.255.00 / udp src is 32 dst is 33 / end"
  */
 static struct rte_flow_item_ipv4 ipv4_udp_spec_1 = {
-	{ 0, 0, 0, 0, 0, 0, IPPROTO_UDP, 0,
+	{ { .version_ihl = 0}, 0, 0, 0, 0, 0, IPPROTO_UDP, 0,
 	  RTE_IPV4(2, 2, 2, 3), RTE_IPV4(2, 2, 2, 7)}
 };
 static const struct rte_flow_item_ipv4 ipv4_mask_24 = {
@@ -131,7 +131,7 @@ static struct rte_flow_item  end_item = { RTE_FLOW_ITEM_TYPE_END,
  *  dst mask 255.255.255.00 / tcp src is 16 dst is 17 / end"
  */
 static struct rte_flow_item_ipv4 ipv4_tcp_spec_1 = {
-	{ 0, 0, 0, 0, 0, 0, IPPROTO_TCP, 0,
+	{ { .version_ihl = 0}, 0, 0, 0, 0, 0, IPPROTO_TCP, 0,
 	  RTE_IPV4(1, 2, 3, 4), RTE_IPV4(5, 6, 7, 8)}
 };
 
@@ -150,8 +150,8 @@ static struct rte_flow_item  tcp_item_1 = { RTE_FLOW_ITEM_TYPE_TCP,
  *  dst mask 255.255.255.00 / sctp src is 16 dst is 17/ end"
  */
 static struct rte_flow_item_ipv4 ipv4_sctp_spec_1 = {
-	{ 0, 0, 0, 0, 0, 0, IPPROTO_SCTP, 0, RTE_IPV4(11, 12, 13, 14),
-	RTE_IPV4(15, 16, 17, 18)}
+	{ { .version_ihl = 0}, 0, 0, 0, 0, 0, IPPROTO_SCTP, 0,
+	RTE_IPV4(11, 12, 13, 14), RTE_IPV4(15, 16, 17, 18)}
 };
 
 static struct rte_flow_item_sctp sctp_spec_1 = {
diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
index a2fe766d4b..040f4a8868 100644
--- a/doc/guides/rel_notes/deprecation.rst
+++ b/doc/guides/rel_notes/deprecation.rst
@@ -167,12 +167,6 @@ Deprecation Notices
 * net: ``s_addr`` and ``d_addr`` fields of ``rte_ether_hdr`` structure
   will be renamed in DPDK 21.11 to avoid conflict with Windows Sockets headers.
 
-* net: The structure ``rte_ipv4_hdr`` will have two unions.
-  The first union is for existing ``version_ihl`` byte
-  and new bitfield for version and IHL.
-  The second union is for existing ``fragment_offset``
-  and new bitfield for fragment flags and offset.
-
 * vhost: ``rte_vdpa_register_device``, ``rte_vdpa_unregister_device``,
   ``rte_vhost_host_notifier_ctrl`` and ``rte_vdpa_relay_vring_used`` vDPA
   driver interface will be marked as internal in DPDK v21.11.
diff --git a/doc/guides/rel_notes/release_21_11.rst b/doc/guides/rel_notes/release_21_11.rst
index dfc2cbdeed..4fb4a1dac4 100644
--- a/doc/guides/rel_notes/release_21_11.rst
+++ b/doc/guides/rel_notes/release_21_11.rst
@@ -187,6 +187,9 @@ API Changes
   the crypto/security operation. This field will be used to communicate
   events such as soft expiry with IPsec in lookaside mode.
 
+* net: Add ``version`` and ``ihl`` bit-fields to ``struct rte_ipv4_hdr``.
+  Existing ``version_ihl`` field was kept for backward compatibility.
+
 
 ABI Changes
 -----------
diff --git a/lib/net/rte_ip.h b/lib/net/rte_ip.h
index 05948b69b7..89a68d9433 100644
--- a/lib/net/rte_ip.h
+++ b/lib/net/rte_ip.h
@@ -38,7 +38,21 @@ extern "C" {
  * IPv4 Header
  */
 struct rte_ipv4_hdr {
-	uint8_t  version_ihl;		/**< version and header length */
+	__extension__
+	union {
+		uint8_t version_ihl;    /**< version and header length */
+		struct {
+#if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN
+			uint8_t ihl:4;     /**< header length */
+			uint8_t version:4; /**< version */
+#elif RTE_BYTE_ORDER == RTE_BIG_ENDIAN
+			uint8_t version:4; /**< version */
+			uint8_t ihl:4;     /**< header length */
+#else
+#error "setup endian definition"
+#endif
+		};
+	};
 	uint8_t  type_of_service;	/**< type of service */
 	rte_be16_t total_length;	/**< length of packet */
 	rte_be16_t packet_id;		/**< packet ID */
-- 
2.33.0