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

[wenxuanx.wu@intel.com]

From: Wenxuan Wu <wenxuanx.wu@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 happens
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.

struct rte_eth_rxseg_split {

        struct rte_mempool *mp; /* memory pools to allocate segment from */
        uint16_t length; /* segment maximal data length,
                            configures "split point" */
        uint16_t offset; /* data offset from beginning
                            of mbuf data buffer */
        uint32_t proto_hdr; /* inner/outer L2/L3/L4 protocol header,
			       configures "split point" */
    };

If both inner and outer L2/L3/L4 level protocol header split can be
supported by a PMD. Corresponding protocol header capability is
RTE_PTYPE_L2_ETHER, RTE_PTYPE_L3_IPV4, RTE_PTYPE_L3_IPV6, RTE_PTYPE_L4_TCP,
RTE_PTYPE_L4_UDP, RTE_PTYPE_L4_SCTP, RTE_PTYPE_INNER_L2_ETHER,
RTE_PTYPE_INNER_L3_IPV4, RTE_PTYPE_INNER_L3_IPV6, RTE_PTYPE_INNER_L4_TCP,
RTE_PTYPE_INNER_L4_UDP, RTE_PTYPE_INNER_L4_SCTP.

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

The packet consists of MAC_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. For length based
buffer split, the mp, length, offset field in Rx packet segment should
be configured, while the proto_hdr field should not be configured.
For protocol header based buffer split, the mp, offset, proto_hdr field
in Rx packet segment should be configured, while the length field should
not be configured.

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: Xuan Ding <xuan.ding@intel.com>
Signed-off-by: Wenxuan Wu <wenxuanx.wu@intel.com>
Signed-off-by: Yuan Wang <yuanx.wang@intel.com>
Reviewed-by: Qi Zhang <qi.z.zhang@intel.com>
Acked-by: Ray Kinsella <mdr@ashroe.eu>
---
 lib/ethdev/rte_ethdev.c | 32 +++++++++++++++++++++++++++++++-
 lib/ethdev/rte_ethdev.h | 14 +++++++++++++-
 2 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
index e1f2a0ffe3..b89e30296f 100644
--- a/lib/ethdev/rte_ethdev.c
+++ b/lib/ethdev/rte_ethdev.c
@@ -1662,6 +1662,7 @@ rte_eth_rx_queue_check_split(uint16_t port_id,
 		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");
@@ -1695,7 +1696,36 @@ rte_eth_rx_queue_check_split(uint16_t port_id,
 		}
 		offset += seg_idx != 0 ? 0 : RTE_PKTMBUF_HEADROOM;
 		*mbp_buf_size = rte_pktmbuf_data_room_size(mpl);
-
+		uint32_t ptypes_mask;
+		int ret = rte_eth_supported_hdrs_get(port_id, &ptypes_mask);
+
+		if (ret == ENOTSUP || ptypes_mask == RTE_PTYPE_UNKNOWN) {
+			/* Split at fixed length. */
+			length = length != 0 ? length : *mbp_buf_size;
+			if (*mbp_buf_size < length + offset) {
+				RTE_ETHDEV_LOG(ERR,
+					"%s mbuf_data_room_size %u < %u (segment length=%u + segment offset=%u)\n",
+					mpl->name, *mbp_buf_size,
+					length + offset, length, offset);
+				return -EINVAL;
+			}
+		} else if (ret == 0) {
+			/* Split after specified protocol header. */
+			if (proto_hdr & ~ptypes_mask) {
+				RTE_ETHDEV_LOG(ERR,
+					"Protocol header 0x%x is not supported.\n",
+					proto_hdr & ~ptypes_mask);
+				return -EINVAL;
+			}
+			if (*mbp_buf_size < offset) {
+				RTE_ETHDEV_LOG(ERR,
+						"%s mbuf_data_room_size %u < %u segment offset)\n",
+						mpl->name, *mbp_buf_size,
+						offset);
+				return -EINVAL;
+			}
+		} else {
+			return ret;
 		}
 	}
 	return 0;
diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
index 72cac1518e..7df40f9f9b 100644
--- a/lib/ethdev/rte_ethdev.h
+++ b/lib/ethdev/rte_ethdev.h
@@ -1176,6 +1176,9 @@ 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.
@@ -1197,12 +1200,21 @@ 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 should not be configured.
+ *
+ * - Protocol header based buffer split:
+ *     - mp, offset, proto_hdr should be configured.
+ *     - The length field should not be configured.
  */
 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. */
+	/**< Supported ptypes mask of a specific pmd, configures split point. */
+	uint32_t proto_hdr;
 };
 
 /**
-- 
2.25.1