[dpdk-dev] [PATCH v3 3/5] mlx5: add RX CRC stripping configuration

[Adrien Mazarguil <adrien.mazarguil@6wind.com>]

From: Olga Shern <olgas@mellanox.com>

Until now, CRC was always stripped by hardware. This feature can be
configured since MLNX_OFED >= 3.2.

Signed-off-by: Olga Shern <olgas@mellanox.com>
---
 doc/guides/nics/mlx5.rst               |  2 ++
 doc/guides/rel_notes/release_16_04.rst |  6 ++++++
 drivers/net/mlx5/Makefile              |  5 +++++
 drivers/net/mlx5/mlx5.c                |  7 +++++++
 drivers/net/mlx5/mlx5.h                |  1 +
 drivers/net/mlx5/mlx5_rxq.c            | 24 ++++++++++++++++++++++++
 drivers/net/mlx5/mlx5_rxtx.c           |  6 ++++--
 drivers/net/mlx5/mlx5_rxtx.h           |  1 +
 8 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
index f0d8a7e..8b63f3f 100644
--- a/doc/guides/nics/mlx5.rst
+++ b/doc/guides/nics/mlx5.rst
@@ -84,6 +84,7 @@ Features
 - Support for multiple MAC addresses.
 - VLAN filtering.
 - RX VLAN stripping.
+- RX CRC stripping configuration.
 - Promiscuous mode.
 - Multicast promiscuous mode.
 - Hardware checksum offloads.
@@ -232,6 +233,7 @@ Currently supported by DPDK:
 
     - Flow director.
     - RX VLAN stripping.
+    - RX CRC stripping configuration.
 
 - Minimum firmware version:
 
diff --git a/doc/guides/rel_notes/release_16_04.rst b/doc/guides/rel_notes/release_16_04.rst
index ceef9b7..a498ef7 100644
--- a/doc/guides/rel_notes/release_16_04.rst
+++ b/doc/guides/rel_notes/release_16_04.rst
@@ -138,6 +138,12 @@ This section should contain new features added in this release. Sample format:
 
   Implemented TX support in secondary processes (like mlx4).
 
+* **Added mlx5 RX CRC stripping configuration.**
+
+  Until now, CRC was always stripped. It can now be configured.
+
+  Only available with Mellanox OFED >= 3.2.
+
 * **Added af_packet dynamic removal function.**
 
   Af_packet device can now be detached using API, like other PMD devices.
diff --git a/drivers/net/mlx5/Makefile b/drivers/net/mlx5/Makefile
index 7076ae3..cc6de2d 100644
--- a/drivers/net/mlx5/Makefile
+++ b/drivers/net/mlx5/Makefile
@@ -137,6 +137,11 @@ mlx5_autoconf.h: $(RTE_SDK)/scripts/auto-config-h.sh
 		infiniband/verbs.h \
 		enum IBV_EXP_CQ_RX_TCP_PACKET \
 		$(AUTOCONF_OUTPUT)
+	$Q sh -- '$<' '$@' \
+		HAVE_VERBS_FCS \
+		infiniband/verbs.h \
+		enum IBV_EXP_CREATE_WQ_FLAG_SCATTER_FCS \
+		$(AUTOCONF_OUTPUT)
 
 $(SRCS-$(CONFIG_RTE_LIBRTE_MLX5_PMD):.c=.o): mlx5_autoconf.h
 
diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
index 998e6f0..acfb365 100644
--- a/drivers/net/mlx5/mlx5.c
+++ b/drivers/net/mlx5/mlx5.c
@@ -417,6 +417,13 @@ mlx5_pci_devinit(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
 		DEBUG("VLAN stripping is %ssupported",
 		      (priv->hw_vlan_strip ? "" : "not "));
 
+#ifdef HAVE_VERBS_FCS
+		priv->hw_fcs_strip = !!(exp_device_attr.exp_device_cap_flags &
+					IBV_EXP_DEVICE_SCATTER_FCS);
+#endif /* HAVE_VERBS_FCS */
+		DEBUG("FCS stripping configuration is %ssupported",
+		      (priv->hw_fcs_strip ? "" : "not "));
+
 #else /* HAVE_EXP_QUERY_DEVICE */
 		priv->ind_table_max_size = RSS_INDIRECTION_TABLE_SIZE;
 #endif /* HAVE_EXP_QUERY_DEVICE */
diff --git a/drivers/net/mlx5/mlx5.h b/drivers/net/mlx5/mlx5.h
index bad9283..9690827 100644
--- a/drivers/net/mlx5/mlx5.h
+++ b/drivers/net/mlx5/mlx5.h
@@ -103,6 +103,7 @@ struct priv {
 	unsigned int hw_csum:1; /* Checksum offload is supported. */
 	unsigned int hw_csum_l2tun:1; /* Same for L2 tunnels. */
 	unsigned int hw_vlan_strip:1; /* VLAN stripping is supported. */
+	unsigned int hw_fcs_strip:1; /* FCS stripping is supported. */
 	unsigned int vf:1; /* This is a VF device. */
 	unsigned int pending_alarm:1; /* An alarm is pending. */
 	/* RX/TX queues. */
diff --git a/drivers/net/mlx5/mlx5_rxq.c b/drivers/net/mlx5/mlx5_rxq.c
index 3d84f41..19a1119 100644
--- a/drivers/net/mlx5/mlx5_rxq.c
+++ b/drivers/net/mlx5/mlx5_rxq.c
@@ -1258,6 +1258,30 @@ rxq_setup(struct rte_eth_dev *dev, struct rxq *rxq, uint16_t desc,
 				  0),
 #endif /* HAVE_EXP_DEVICE_ATTR_VLAN_OFFLOADS */
 	};
+
+#ifdef HAVE_VERBS_FCS
+	/* By default, FCS (CRC) is stripped by hardware. */
+	if (dev->data->dev_conf.rxmode.hw_strip_crc) {
+		tmpl.crc_present = 0;
+	} else if (priv->hw_fcs_strip) {
+		/* Ask HW/Verbs to leave CRC in place when supported. */
+		attr.wq.flags |= IBV_EXP_CREATE_WQ_FLAG_SCATTER_FCS;
+		attr.wq.comp_mask |= IBV_EXP_CREATE_WQ_FLAGS;
+		tmpl.crc_present = 1;
+	} else {
+		WARN("%p: CRC stripping has been disabled but will still"
+		     " be performed by hardware, make sure MLNX_OFED and"
+		     " firmware are up to date",
+		     (void *)dev);
+		tmpl.crc_present = 0;
+	}
+	DEBUG("%p: CRC stripping is %s, %u bytes will be subtracted from"
+	      " incoming frames to hide it",
+	      (void *)dev,
+	      tmpl.crc_present ? "disabled" : "enabled",
+	      tmpl.crc_present << 2);
+#endif /* HAVE_VERBS_FCS */
+
 	tmpl.wq = ibv_exp_create_wq(priv->ctx, &attr.wq);
 	if (tmpl.wq == NULL) {
 		ret = (errno ? errno : EINVAL);
diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
index 4919189..34340d2 100644
--- a/drivers/net/mlx5/mlx5_rxtx.c
+++ b/drivers/net/mlx5/mlx5_rxtx.c
@@ -828,7 +828,8 @@ mlx5_rx_burst_sp(void *dpdk_rxq, struct rte_mbuf **pkts, uint16_t pkts_n)
 		}
 		if (ret == 0)
 			break;
-		len = ret;
+		assert(ret >= (rxq->crc_present << 2));
+		len = ret - (rxq->crc_present << 2);
 		pkt_buf_len = len;
 		/*
 		 * Replace spent segments with new ones, concatenate and
@@ -1040,7 +1041,8 @@ mlx5_rx_burst(void *dpdk_rxq, struct rte_mbuf **pkts, uint16_t pkts_n)
 		}
 		if (ret == 0)
 			break;
-		len = ret;
+		assert(ret >= (rxq->crc_present << 2));
+		len = ret - (rxq->crc_present << 2);
 		rep = __rte_mbuf_raw_alloc(rxq->mp);
 		if (unlikely(rep == NULL)) {
 			/*
diff --git a/drivers/net/mlx5/mlx5_rxtx.h b/drivers/net/mlx5/mlx5_rxtx.h
index 6a0087e..61be3e4 100644
--- a/drivers/net/mlx5/mlx5_rxtx.h
+++ b/drivers/net/mlx5/mlx5_rxtx.h
@@ -116,6 +116,7 @@ struct rxq {
 	unsigned int csum:1; /* Enable checksum offloading. */
 	unsigned int csum_l2tun:1; /* Same for L2 tunnels. */
 	unsigned int vlan_strip:1; /* Enable VLAN stripping. */
+	unsigned int crc_present:1; /* CRC must be subtracted. */
 	union {
 		struct rxq_elt_sp (*sp)[]; /* Scattered RX elements. */
 		struct rxq_elt (*no_sp)[]; /* RX elements. */
-- 
2.1.4