[PATCH v9 2/4] ethdev: introduce protocol hdr based buffer split

[Yuan Wang <yuanx.wang@intel.com>]

Currently, Rx buffer split supports length based split. With Rx queue
offload RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT enabled and Rx packet segment
configured, PMD will be able to split the received packets into
multiple segments.

However, length based buffer split is not suitable for NICs that do split
based on protocol headers. Given an arbitrarily variable length in Rx
packet segment, it is almost impossible to pass a fixed protocol header to
driver. Besides, the existence of tunneling results in the composition of
a packet is various, which makes the situation even worse.

This patch extends current buffer split to support protocol header based
buffer split. A new proto_hdr field is introduced in the reserved field
of rte_eth_rxseg_split structure to specify protocol header. The proto_hdr
field defines the split position of packet, splitting will always happen
after the protocol header defined in the Rx packet segment. When Rx queue
offload RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT is enabled and corresponding
protocol header is configured, driver will split the ingress packets into
multiple segments.

Examples for proto_hdr field defines:
To split after ETH-IPV4-UDP, it should be defined as
proto_hdr = RTE_PTYPE_L2_ETHER | RTE_PTYPE_L3_IPV4_EXT_UNKNOWN |
            RTE_PTYPE_L4_UDP

For inner ETH-IPV4-UDP, it should be defined as
proto_hdr = RTE_PTYPE_TUNNEL_GRENAT | RTE_PTYPE_INNER_L2_ETHER |
            RTE_PTYPE_INNER_L3_IPV4_EXT_UNKNOWN | RTE_PTYPE_INNER_L4_UDP

If the protocol header is repeated with the previously defined one,
the repeated part should be omitted. For example, split after ETH, ETH-IPV4
and ETH-IPV4-UDP, it should be defined as
proto_hdr0 = RTE_PTYPE_L2_ETHER
proto_hdr1 = RTE_PTYPE_L3_IPV4_EXT_UNKNOWN
proto_hdr2 = RTE_PTYPE_L4_UDP

struct rte_eth_rxseg_split {
        struct rte_mempool *mp;
        uint16_t length;
        uint16_t offset;
        uint32_t proto_hdr;
};

If protocol header split can be supported by a PMD, the
rte_eth_buffer_split_get_supported_hdr_ptypes function can
be used to obtain a list of these protocol headers.

For example, let's suppose we configured the Rx queue with the
following segments:
        seg0 - pool0, proto_hdr0=RTE_PTYPE_L2_ETHER | RTE_PTYPE_L3_IPV4,
               off0=2B
        seg1 - pool1, proto_hdr1=RTE_PTYPE_L4_UDP, off1=128B
        seg2 - pool2, proto_hdr2=0, off1=0B

The packet consists of ETH_IPV4_UDP_PAYLOAD will be split like
following:
        seg0 - ipv4 header @ RTE_PKTMBUF_HEADROOM + 2 in mbuf from pool0
        seg1 - udp header @ 128 in mbuf from pool1
        seg2 - payload @ 0 in mbuf from pool2

Now buffer split can be configured in two modes. User can choose length
or protocol header to configure buffer split according to NIC's
capability. For length based buffer split, the mp, length, offset field
in Rx packet segment should be configured, while the proto_hdr field
must be 0. For protocol header based buffer split, the mp, offset,
proto_hdr field in Rx packet segment should be configured, while the
length field must be 0.

Note: When protocol header split is enabled, NIC may receive packets
which do not match all the protocol headers within the Rx segments.
At this point, NIC will have two possible split behaviors according to
matching results, one is exact match, another is longest match.
The split result of NIC must belong to one of them.

The exact match means NIC only do split when the packets exactly match all
the protocol headers in the segments. Otherwise, the whole packet will be
put into the last valid mempool. The longest match means NIC will do split
until packets mismatch the protocol header in the segments. The rest will
be put into the last valid pool.

Pseudo-code for exact match:
FOR each seg in segs except last one
    IF proto_hdr is not matched THEN
        BREAK
    END IF
END FOR
IF loop breaked THEN
    put whole pkt in last seg
ELSE
    put protocol header in each seg
    put everything else in last seg
END IF

Pseudo-code for longest match:
FOR each seg in segs except last one
    IF proto_hdr is matched THEN
        put protocol header in seg
    ELSE
        BREAK
    END IF
END FOR
put everything else in last seg

The split limitations imposed by underlying driver is reported in the
rte_eth_dev_info->rx_seg_capa field. The memory attributes for the split
parts may differ either, dpdk memory and external memory, respectively.

Signed-off-by: Yuan Wang <yuanx.wang@intel.com>
Signed-off-by: Xuan Ding <xuan.ding@intel.com>
Signed-off-by: Wenxuan Wu <wenxuanx.wu@intel.com>
---
 doc/guides/rel_notes/release_22_11.rst |  7 ++
 lib/ethdev/rte_ethdev.c                | 95 +++++++++++++++++++++++---
 lib/ethdev/rte_ethdev.h                | 37 +++++++++-
 3 files changed, 127 insertions(+), 12 deletions(-)

diff --git a/doc/guides/rel_notes/release_22_11.rst b/doc/guides/rel_notes/release_22_11.rst
index 16aca14bab..b4329d4cb0 100644
--- a/doc/guides/rel_notes/release_22_11.rst
+++ b/doc/guides/rel_notes/release_22_11.rst
@@ -193,6 +193,8 @@ New Features
 
   * Added ``rte_eth_buffer_split_get_supported_hdr_ptypes()``, to get supported
     header protocols of a PMD to split.
+  * Supported protocol-based buffer split using added ``proto_hdr``
+    in structure ``rte_eth_rxseg_split``.
 
 
 Removed Items
@@ -338,6 +340,11 @@ API Changes
   for per-queue packet split offload,
   which is configured by ``rte_eth_rxseg_split``.
 
+* ethdev: The ``reserved`` field in the ``rte_eth_rxseg_split`` structure is
+  replaced with ``proto_hdr`` to support protocol header based buffer split.
+  User can choose length or protocol header to configure buffer split
+  according to NIC's capability.
+
 * ethdev: Changed the type of the parameter ``rate`` of the function
   ``rte_eth_set_queue_rate_limit()`` from ``uint16_t`` to ``uint32_t``
   to support more than 64 Gbps.
diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
index 79d1f9b993..3696d4f044 100644
--- a/lib/ethdev/rte_ethdev.c
+++ b/lib/ethdev/rte_ethdev.c
@@ -1687,15 +1687,38 @@ rte_eth_check_rx_mempool(struct rte_mempool *mp, uint16_t offset,
 }
 
 static int
-rte_eth_rx_queue_check_split(const struct rte_eth_rxseg_split *rx_seg,
-			     uint16_t n_seg, uint32_t *mbp_buf_size,
-			     const struct rte_eth_dev_info *dev_info)
+eth_dev_buffer_split_get_supported_hdrs_helper(uint16_t port_id, uint32_t **ptypes)
+{
+	int cnt;
+
+	cnt = rte_eth_buffer_split_get_supported_hdr_ptypes(port_id, NULL, 0);
+	if (cnt <= 0)
+		return cnt;
+
+	*ptypes = malloc(sizeof(uint32_t) * cnt);
+	if (*ptypes == NULL)
+		return -ENOMEM;
+
+	return rte_eth_buffer_split_get_supported_hdr_ptypes(port_id, *ptypes, cnt);
+}
+
+static int
+rte_eth_rx_queue_check_split(uint16_t port_id,
+			const struct rte_eth_rxseg_split *rx_seg,
+			uint16_t n_seg, uint32_t *mbp_buf_size,
+			const struct rte_eth_dev_info *dev_info)
 {
 	const struct rte_eth_rxseg_capa *seg_capa = &dev_info->rx_seg_capa;
 	struct rte_mempool *mp_first;
 	uint32_t offset_mask;
 	uint16_t seg_idx;
 	int ret;
+	int ptype_cnt;
+	uint32_t *ptypes, prev_proto_hdrs;
+	int i;
+
+	ret = 0;
+	prev_proto_hdrs = RTE_PTYPE_UNKNOWN;
 
 	if (n_seg > seg_capa->max_nseg) {
 		RTE_ETHDEV_LOG(ERR,
@@ -1709,42 +1732,92 @@ rte_eth_rx_queue_check_split(const struct rte_eth_rxseg_split *rx_seg,
 	 */
 	mp_first = rx_seg[0].mp;
 	offset_mask = RTE_BIT32(seg_capa->offset_align_log2) - 1;
+
+	ptypes = NULL;
+	ptype_cnt = eth_dev_buffer_split_get_supported_hdrs_helper(port_id, &ptypes);
+
 	for (seg_idx = 0; seg_idx < n_seg; seg_idx++) {
 		struct rte_mempool *mpl = rx_seg[seg_idx].mp;
 		uint32_t length = rx_seg[seg_idx].length;
 		uint32_t offset = rx_seg[seg_idx].offset;
+		uint32_t proto_hdr = rx_seg[seg_idx].proto_hdr;
 
 		if (mpl == NULL) {
 			RTE_ETHDEV_LOG(ERR, "null mempool pointer\n");
-			return -EINVAL;
+			ret = -EINVAL;
+			goto out;
 		}
 		if (seg_idx != 0 && mp_first != mpl &&
 		    seg_capa->multi_pools == 0) {
 			RTE_ETHDEV_LOG(ERR, "Receiving to multiple pools is not supported\n");
-			return -ENOTSUP;
+			ret = -ENOTSUP;
+			goto out;
 		}
 		if (offset != 0) {
 			if (seg_capa->offset_allowed == 0) {
 				RTE_ETHDEV_LOG(ERR, "Rx segmentation with offset is not supported\n");
-				return -ENOTSUP;
+				ret = -ENOTSUP;
+				goto out;
 			}
 			if (offset & offset_mask) {
 				RTE_ETHDEV_LOG(ERR, "Rx segmentation invalid offset alignment %u, %u\n",
 					       offset,
 					       seg_capa->offset_align_log2);
-				return -EINVAL;
+				ret = -EINVAL;
+				goto out;
 			}
 		}
 
 		offset += seg_idx != 0 ? 0 : RTE_PKTMBUF_HEADROOM;
 		*mbp_buf_size = rte_pktmbuf_data_room_size(mpl);
-		length = length != 0 ? length : *mbp_buf_size;
+		if (proto_hdr != 0) {
+			/* Split based on protocol headers. */
+			if (length != 0) {
+				RTE_ETHDEV_LOG(ERR,
+					"Do not set length split and protocol split within a segment\n"
+					);
+				ret = -EINVAL;
+				goto out;
+			}
+			if ((proto_hdr & prev_proto_hdrs) != 0) {
+				RTE_ETHDEV_LOG(ERR,
+					"Repeat with previous protocol headers or proto-split after length-based split\n"
+					);
+				ret = -EINVAL;
+				goto out;
+			}
+			if (ptype_cnt <= 0) {
+				RTE_ETHDEV_LOG(ERR,
+					"Port %u failed to get supported buffer split header protocols\n",
+					port_id);
+				ret = -ENOTSUP;
+				goto out;
+			}
+			for (i = 0; i < ptype_cnt; i++) {
+				if ((prev_proto_hdrs | proto_hdr) == ptypes[i])
+					break;
+			}
+			if (i == ptype_cnt) {
+				RTE_ETHDEV_LOG(ERR,
+					"Requested Rx split header protocols 0x%x is not supported.\n",
+					proto_hdr);
+				ret = -EINVAL;
+				goto out;
+			}
+			prev_proto_hdrs |= proto_hdr;
+		} else {
+			/* Split at fixed length. */
+			length = length != 0 ? length : *mbp_buf_size;
+			prev_proto_hdrs = RTE_PTYPE_ALL_MASK;
+		}
 
 		ret = rte_eth_check_rx_mempool(mpl, offset, length);
 		if (ret != 0)
-			return ret;
+			goto out;
 	}
-	return 0;
+out:
+	free(ptypes);
+	return ret;
 }
 
 static int
@@ -1846,7 +1919,7 @@ rte_eth_rx_queue_setup(uint16_t port_id, uint16_t rx_queue_id,
 		n_seg = rx_conf->rx_nseg;
 
 		if (rx_offloads & RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT) {
-			ret = rte_eth_rx_queue_check_split(rx_seg, n_seg,
+			ret = rte_eth_rx_queue_check_split(port_id, rx_seg, n_seg,
 							   &mbp_buf_size,
 							   &dev_info);
 			if (ret != 0)
diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
index f9da569179..811c029bf8 100644
--- a/lib/ethdev/rte_ethdev.h
+++ b/lib/ethdev/rte_ethdev.h
@@ -994,6 +994,9 @@ struct rte_eth_txmode {
  *   specified in the first array element, the second buffer, from the
  *   pool in the second element, and so on.
  *
+ * - The proto_hdrs in the elements define the split position of
+ *   received packets.
+ *
  * - The offsets from the segment description elements specify
  *   the data offset from the buffer beginning except the first mbuf.
  *   The first segment offset is added with RTE_PKTMBUF_HEADROOM.
@@ -1015,12 +1018,44 @@ struct rte_eth_txmode {
  *     - pool from the last valid element
  *     - the buffer size from this pool
  *     - zero offset
+ *
+ * - Length based buffer split:
+ *     - mp, length, offset should be configured.
+ *     - The proto_hdr field must be 0.
+ *
+ * - Protocol header based buffer split:
+ *     - mp, offset, proto_hdr should be configured.
+ *     - The length field must be 0.
+ *     - The proto_hdr field in the last segment should be 0.
+ *
+ * - When protocol header split is enabled, NIC may receive packets
+ *   which do not match all the protocol headers within the Rx segments.
+ *   At this point, NIC will have two possible split behaviors according to
+ *   matching results, one is exact match, another is longest match.
+ *   The split result of NIC must belong to one of them.
+ *   The exact match means NIC only do split when the packets exactly match all
+ *   the protocol headers in the segments. Otherwise, the whole packet will be
+ *   put into the last valid mempool. The longest match means NIC will do split
+ *   until packets mismatch the protocol header in the segments. The rest will
+ *   be put into the last valid pool.
  */
 struct rte_eth_rxseg_split {
 	struct rte_mempool *mp; /**< Memory pool to allocate segment from. */
 	uint16_t length; /**< Segment data length, configures split point. */
 	uint16_t offset; /**< Data offset from beginning of mbuf data buffer. */
-	uint32_t reserved; /**< Reserved field. */
+	/**
+	 * Proto_hdr defines a bit mask of the protocol sequence as RTE_PTYPE_*,
+	 * configures split point. The last RTE_PTYPE* in the mask indicates the
+	 * split position.
+	 *
+	 * If one protocol header is defined to split packets into two segments,
+	 * for non-tunneling packets, the complete protocol sequence should be defined.
+	 * For tunneling packets, for simplicity, only the tunnel and inner part of
+	 * comple protocol sequence is required.
+	 * If several protocol headers are defined to split packets into multi-segments,
+	 * the repeated parts of adjacent segments should be omitted.
+	 */
+	uint32_t proto_hdr;
 };
 
 /**
-- 
2.25.1