[dpdk-stable] [PATCH v2] net/ixgbe: fix UDP zero checksum error

[Haiyue Wang <haiyue.wang@intel.com>]

There is an 82599 errata that UDP frames with a zero checksum are
incorrectly marked as checksum invalid by the hardware.  This was
leading to misleading PKT_RX_L4_CKSUM_BAD flag.

This patch changes the bad UDP checksum to PKT_RX_L4_CKSUM_UNKNOWN,
so the software application will then have to recompute the checksum
itself if needed.

Bugzilla ID: 629

Fixes: af75078fece3 ("first public release")
Cc: stable@dpdk.org

Reported-by: Paolo Valerio <pvalerio@redhat.com>
Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
---
v2: Change the always GOOD checksum to UNKOWN if BAD.
---
 doc/guides/nics/ixgbe.rst              |  7 ++++++
 drivers/net/ixgbe/ixgbe_rxtx.c         | 30 ++++++++++++++++++++----
 drivers/net/ixgbe/ixgbe_rxtx.h         |  2 ++
 drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c | 32 +++++++++++++++++++++++---
 4 files changed, 64 insertions(+), 7 deletions(-)

diff --git a/doc/guides/nics/ixgbe.rst b/doc/guides/nics/ixgbe.rst
index 696cbd93ba..41b07b9aff 100644
--- a/doc/guides/nics/ixgbe.rst
+++ b/doc/guides/nics/ixgbe.rst
@@ -287,6 +287,13 @@ the VFs which are required.::
 Currently hot-plugging of representor ports is not supported so all required
 representors must be specified on the creation of the PF.
 
+Limitations or Known issues
+---------------------------
+The 82599 hardware errata: UDP frames with a zero checksum can be marked as
+checksum errors. To support UDP zero checksum, the bad UDP checksum is marked
+as PKT_RX_L4_CKSUM_UNKNOWN, so the application will recompute the checksum to
+validate it again.
+
 Supported Chipsets and NICs
 ---------------------------
 
diff --git a/drivers/net/ixgbe/ixgbe_rxtx.c b/drivers/net/ixgbe/ixgbe_rxtx.c
index 72d27f35ca..950b7894e0 100644
--- a/drivers/net/ixgbe/ixgbe_rxtx.c
+++ b/drivers/net/ixgbe/ixgbe_rxtx.c
@@ -1466,7 +1466,8 @@ rx_desc_status_to_pkt_flags(uint32_t rx_status, uint64_t vlan_flags)
 }
 
 static inline uint64_t
-rx_desc_error_to_pkt_flags(uint32_t rx_status)
+rx_desc_error_to_pkt_flags(uint32_t rx_status, uint16_t pkt_info,
+			   uint8_t rx_udp_csum_zero_err)
 {
 	uint64_t pkt_flags;
 
@@ -1483,6 +1484,15 @@ rx_desc_error_to_pkt_flags(uint32_t rx_status)
 	pkt_flags = error_to_pkt_flags_map[(rx_status >>
 		IXGBE_RXDADV_ERR_CKSUM_BIT) & IXGBE_RXDADV_ERR_CKSUM_MSK];
 
+	/* Mask out the bad UDP checksum error if the hardware has UDP zero
+	 * checksum error issue, so that the software application will then
+	 * have to recompute the checksum itself if needed.
+	 */
+	if ((rx_status & IXGBE_RXDADV_ERR_TCPE) &&
+	    (pkt_info & IXGBE_RXDADV_PKTTYPE_UDP) &&
+	    rx_udp_csum_zero_err)
+		pkt_flags &= ~PKT_RX_L4_CKSUM_BAD;
+
 	if ((rx_status & IXGBE_RXD_STAT_OUTERIPCS) &&
 	    (rx_status & IXGBE_RXDADV_ERR_OUTERIPER)) {
 		pkt_flags |= PKT_RX_EIP_CKSUM_BAD;
@@ -1569,7 +1579,9 @@ ixgbe_rx_scan_hw_ring(struct ixgbe_rx_queue *rxq)
 			/* convert descriptor fields to rte mbuf flags */
 			pkt_flags = rx_desc_status_to_pkt_flags(s[j],
 				vlan_flags);
-			pkt_flags |= rx_desc_error_to_pkt_flags(s[j]);
+			pkt_flags |= rx_desc_error_to_pkt_flags(s[j],
+					(uint16_t)pkt_info[j],
+					rxq->rx_udp_csum_zero_err);
 			pkt_flags |= ixgbe_rxd_pkt_info_to_pkt_flags
 					((uint16_t)pkt_info[j]);
 			mb->ol_flags = pkt_flags;
@@ -1902,7 +1914,9 @@ ixgbe_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		rxm->vlan_tci = rte_le_to_cpu_16(rxd.wb.upper.vlan);
 
 		pkt_flags = rx_desc_status_to_pkt_flags(staterr, vlan_flags);
-		pkt_flags = pkt_flags | rx_desc_error_to_pkt_flags(staterr);
+		pkt_flags = pkt_flags |
+			rx_desc_error_to_pkt_flags(staterr, (uint16_t)pkt_info,
+						   rxq->rx_udp_csum_zero_err);
 		pkt_flags = pkt_flags |
 			ixgbe_rxd_pkt_info_to_pkt_flags((uint16_t)pkt_info);
 		rxm->ol_flags = pkt_flags;
@@ -1995,7 +2009,8 @@ ixgbe_fill_cluster_head_buf(
 	head->vlan_tci = rte_le_to_cpu_16(desc->wb.upper.vlan);
 	pkt_info = rte_le_to_cpu_32(desc->wb.lower.lo_dword.data);
 	pkt_flags = rx_desc_status_to_pkt_flags(staterr, rxq->vlan_flags);
-	pkt_flags |= rx_desc_error_to_pkt_flags(staterr);
+	pkt_flags |= rx_desc_error_to_pkt_flags(staterr, (uint16_t)pkt_info,
+						rxq->rx_udp_csum_zero_err);
 	pkt_flags |= ixgbe_rxd_pkt_info_to_pkt_flags((uint16_t)pkt_info);
 	head->ol_flags = pkt_flags;
 	head->packet_type =
@@ -3116,6 +3131,13 @@ ixgbe_dev_rx_queue_setup(struct rte_eth_dev *dev,
 	else
 		rxq->pkt_type_mask = IXGBE_PACKET_TYPE_MASK_82599;
 
+	/*
+	 * 82599 errata, UDP frames with a 0 checksum can be marked as checksum
+	 * errors.
+	 */
+	if (hw->mac.type == ixgbe_mac_82599EB)
+		rxq->rx_udp_csum_zero_err = 1;
+
 	/*
 	 * Allocate RX ring hardware descriptors. A memzone large enough to
 	 * handle the maximum ring size is allocated in order to allow for
diff --git a/drivers/net/ixgbe/ixgbe_rxtx.h b/drivers/net/ixgbe/ixgbe_rxtx.h
index 8a25e98df6..476ef62cfd 100644
--- a/drivers/net/ixgbe/ixgbe_rxtx.h
+++ b/drivers/net/ixgbe/ixgbe_rxtx.h
@@ -129,6 +129,8 @@ struct ixgbe_rx_queue {
 	uint8_t             crc_len;  /**< 0 if CRC stripped, 4 otherwise. */
 	uint8_t             drop_en;  /**< If not 0, set SRRCTL.Drop_En. */
 	uint8_t             rx_deferred_start; /**< not in global dev start. */
+	/** UDP frames with a 0 checksum can be marked as checksum errors. */
+	uint8_t             rx_udp_csum_zero_err;
 	/** flags to set in mbuf when a vlan is detected. */
 	uint64_t            vlan_flags;
 	uint64_t	    offloads; /**< Rx offloads with DEV_RX_OFFLOAD_* */
diff --git a/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c b/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c
index 9bbffe6119..7610fd93db 100644
--- a/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c
+++ b/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c
@@ -132,9 +132,9 @@ desc_to_olflags_v_ipsec(__m128i descs[4], struct rte_mbuf **rx_pkts)
 
 static inline void
 desc_to_olflags_v(__m128i descs[4], __m128i mbuf_init, uint8_t vlan_flags,
-	struct rte_mbuf **rx_pkts)
+		  uint16_t udp_p_flag, struct rte_mbuf **rx_pkts)
 {
-	__m128i ptype0, ptype1, vtag0, vtag1, csum;
+	__m128i ptype0, ptype1, vtag0, vtag1, csum, udp_csum_skip;
 	__m128i rearm0, rearm1, rearm2, rearm3;
 
 	/* mask everything except rss type */
@@ -161,6 +161,7 @@ desc_to_olflags_v(__m128i descs[4], __m128i mbuf_init, uint8_t vlan_flags,
 		(IXGBE_RXDADV_ERR_TCPE | IXGBE_RXDADV_ERR_IPE) >> 16,
 		IXGBE_RXD_STAT_VP, IXGBE_RXD_STAT_VP,
 		IXGBE_RXD_STAT_VP, IXGBE_RXD_STAT_VP);
+
 	/* map vlan present (0x8), IPE (0x2), L4E (0x1) to ol_flags */
 	const __m128i vlan_csum_map_lo = _mm_set_epi8(
 		0, 0, 0, 0,
@@ -182,12 +183,23 @@ desc_to_olflags_v(__m128i descs[4], __m128i mbuf_init, uint8_t vlan_flags,
 		0, PKT_RX_L4_CKSUM_GOOD >> sizeof(uint8_t), 0,
 		PKT_RX_L4_CKSUM_GOOD >> sizeof(uint8_t));
 
+	/* mask everything except UDP header present if specified */
+	const __m128i udp_hdr_p_msk = _mm_set_epi16
+		(0, 0, 0, 0,
+		 udp_p_flag, udp_p_flag, udp_p_flag, udp_p_flag);
+
+	const __m128i udp_csum_bad_shuf = _mm_set_epi8
+		(0, 0, 0, 0, 0, 0, 0, 0,
+		 0, 0, 0, 0, 0, 0, ~(uint8_t)PKT_RX_L4_CKSUM_BAD, 0xFF);
+
 	ptype0 = _mm_unpacklo_epi16(descs[0], descs[1]);
 	ptype1 = _mm_unpacklo_epi16(descs[2], descs[3]);
 	vtag0 = _mm_unpackhi_epi16(descs[0], descs[1]);
 	vtag1 = _mm_unpackhi_epi16(descs[2], descs[3]);
 
 	ptype0 = _mm_unpacklo_epi32(ptype0, ptype1);
+	/* save the UDP header present information */
+	udp_csum_skip = _mm_and_si128(ptype0, udp_hdr_p_msk);
 	ptype0 = _mm_and_si128(ptype0, rsstype_msk);
 	ptype0 = _mm_shuffle_epi8(rss_flags, ptype0);
 
@@ -215,6 +227,15 @@ desc_to_olflags_v(__m128i descs[4], __m128i mbuf_init, uint8_t vlan_flags,
 
 	vtag1 = _mm_or_si128(ptype0, vtag1);
 
+	/* convert the UDP header present 0x200 to 0x1 for aligning with each
+	 * PKT_RX_L4_CKSUM_BAD value in low byte of 16 bits word ol_flag in
+	 * vtag1 (4x16). Then mask out the bad checksum value by shuffle and
+	 * bit-mask.
+	 */
+	udp_csum_skip = _mm_srli_epi16(udp_csum_skip, 9);
+	udp_csum_skip = _mm_shuffle_epi8(udp_csum_bad_shuf, udp_csum_skip);
+	vtag1 = _mm_and_si128(vtag1, udp_csum_skip);
+
 	/*
 	 * At this point, we have the 4 sets of flags in the low 64-bits
 	 * of vtag1 (4x16).
@@ -341,6 +362,7 @@ _recv_raw_pkts_vec(struct ixgbe_rx_queue *rxq, struct rte_mbuf **rx_pkts,
 	__m128i dd_check, eop_check;
 	__m128i mbuf_init;
 	uint8_t vlan_flags;
+	uint16_t udp_p_flag = 0; /* Rx Descriptor UDP header present */
 
 	/* nb_pkts has to be floor-aligned to RTE_IXGBE_DESCS_PER_LOOP */
 	nb_pkts = RTE_ALIGN_FLOOR(nb_pkts, RTE_IXGBE_DESCS_PER_LOOP);
@@ -365,6 +387,9 @@ _recv_raw_pkts_vec(struct ixgbe_rx_queue *rxq, struct rte_mbuf **rx_pkts,
 				rte_cpu_to_le_32(IXGBE_RXDADV_STAT_DD)))
 		return 0;
 
+	if (rxq->rx_udp_csum_zero_err)
+		udp_p_flag = IXGBE_RXDADV_PKTTYPE_UDP;
+
 	/* 4 packets DD mask */
 	dd_check = _mm_set_epi64x(0x0000000100000001LL, 0x0000000100000001LL);
 
@@ -477,7 +502,8 @@ _recv_raw_pkts_vec(struct ixgbe_rx_queue *rxq, struct rte_mbuf **rx_pkts,
 		sterr_tmp1 = _mm_unpackhi_epi32(descs[1], descs[0]);
 
 		/* set ol_flags with vlan packet type */
-		desc_to_olflags_v(descs, mbuf_init, vlan_flags, &rx_pkts[pos]);
+		desc_to_olflags_v(descs, mbuf_init, vlan_flags, udp_p_flag,
+				  &rx_pkts[pos]);
 
 #ifdef RTE_LIB_SECURITY
 		if (unlikely(use_ipsec))
-- 
2.30.0