[dpdk-dev] [PATCH v1 4/5] net/mlx4: restore UDP RSS by probing capabilities

[Adrien Mazarguil]

Until now, UDP RSS support could not be relied on due to a problem in the
Linux kernel implementation and mlx4 RSS capabilities were not reported at
all, hence the PMD had to make assumptions.

Since both issues will be addressed simultaneously in Linux 4.15 (related
patches already upstream) and likely backported afterward, UDP RSS support
can be enabled by probing RSS capabilities.

Signed-off-by: Adrien Mazarguil <adrien.mazarguil at 6wind.com>
---
 drivers/net/mlx4/mlx4.c      | 20 ++++++++++++++++++++
 drivers/net/mlx4/mlx4.h      |  1 +
 drivers/net/mlx4/mlx4_flow.c | 27 +++++++++++++++------------
 drivers/net/mlx4/mlx4_flow.h |  1 +
 4 files changed, 37 insertions(+), 12 deletions(-)

diff --git a/drivers/net/mlx4/mlx4.c b/drivers/net/mlx4/mlx4.c
index f9e4f9d..025b887 100644
--- a/drivers/net/mlx4/mlx4.c
+++ b/drivers/net/mlx4/mlx4.c
@@ -426,6 +426,7 @@ mlx4_pci_probe(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
 	int err = 0;
 	struct ibv_context *attr_ctx = NULL;
 	struct ibv_device_attr device_attr;
+	struct ibv_device_attr_ex device_attr_ex;
 	struct mlx4_conf conf = {
 		.ports.present = 0,
 	};
@@ -499,6 +500,11 @@ mlx4_pci_probe(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
 	/* Use all ports when none are defined */
 	if (!conf.ports.enabled)
 		conf.ports.enabled = conf.ports.present;
+	/* Retrieve extended device attributes. */
+	if (ibv_query_device_ex(attr_ctx, NULL, &device_attr_ex)) {
+		rte_errno = ENODEV;
+		goto error;
+	}
 	for (i = 0; i < device_attr.phys_port_cnt; i++) {
 		uint32_t port = i + 1; /* ports are indexed from one */
 		struct ibv_context *ctx = NULL;
@@ -573,6 +579,20 @@ mlx4_pci_probe(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
 			 PCI_DEVICE_ID_MELLANOX_CONNECTX3PRO);
 		DEBUG("L2 tunnel checksum offloads are %ssupported",
 		      (priv->hw_csum_l2tun ? "" : "not "));
+		priv->hw_rss_sup = device_attr_ex.rss_caps.rx_hash_fields_mask;
+		if (!priv->hw_rss_sup) {
+			WARN("no RSS capabilities reported; disabling support"
+			     " for UDP RSS");
+			/* Fake support for all possible RSS hash fields. */
+			priv->hw_rss_sup = ~UINT64_C(0);
+			priv->hw_rss_sup = mlx4_conv_rss_hf(priv, -1);
+			/* Filter out known unsupported fields. */
+			priv->hw_rss_sup &=
+				~(uint64_t)(IBV_RX_HASH_SRC_PORT_UDP |
+					    IBV_RX_HASH_DST_PORT_UDP);
+		}
+		DEBUG("supported RSS hash fields mask: %016" PRIx64,
+		      priv->hw_rss_sup);
 		/* Configure the first MAC address by default. */
 		if (mlx4_get_mac(priv, &mac.addr_bytes)) {
 			ERROR("cannot get MAC address, is mlx4_en loaded?"
diff --git a/drivers/net/mlx4/mlx4.h b/drivers/net/mlx4/mlx4.h
index 7721858..e5ab934 100644
--- a/drivers/net/mlx4/mlx4.h
+++ b/drivers/net/mlx4/mlx4.h
@@ -128,6 +128,7 @@ struct priv {
 	uint32_t isolated:1; /**< Toggle isolated mode. */
 	uint32_t hw_csum:1; /**< Checksum offload is supported. */
 	uint32_t hw_csum_l2tun:1; /**< Checksum support for L2 tunnels. */
+	uint64_t hw_rss_sup; /**< Supported RSS hash fields (Verbs format). */
 	struct rte_intr_handle intr_handle; /**< Port interrupt handle. */
 	struct mlx4_drop *drop; /**< Shared resources for drop flow rules. */
 	LIST_HEAD(, mlx4_rss) rss; /**< Shared targets for Rx flow rules. */
diff --git a/drivers/net/mlx4/mlx4_flow.c b/drivers/net/mlx4/mlx4_flow.c
index 7397dde..a41d99d 100644
--- a/drivers/net/mlx4/mlx4_flow.c
+++ b/drivers/net/mlx4/mlx4_flow.c
@@ -108,6 +108,8 @@ struct mlx4_drop {
  * This function returns the supported (default) set when @p rss_hf has
  * special value (uint64_t)-1.
  *
+ * @param priv
+ *   Pointer to private structure.
  * @param rss_hf
  *   Hash fields in DPDK format (see struct rte_eth_rss_conf).
  *
@@ -115,8 +117,8 @@ struct mlx4_drop {
  *   A valid Verbs RSS hash fields mask for mlx4 on success, (uint64_t)-1
  *   otherwise and rte_errno is set.
  */
-static uint64_t
-mlx4_conv_rss_hf(uint64_t rss_hf)
+uint64_t
+mlx4_conv_rss_hf(struct priv *priv, uint64_t rss_hf)
 {
 	enum { IPV4, IPV6, TCP, UDP, };
 	const uint64_t in[] = {
@@ -136,11 +138,9 @@ mlx4_conv_rss_hf(uint64_t rss_hf)
 		[TCP] = (ETH_RSS_NONFRAG_IPV4_TCP |
 			 ETH_RSS_NONFRAG_IPV6_TCP |
 			 ETH_RSS_IPV6_TCP_EX),
-		/*
-		 * UDP support is temporarily disabled due to an
-		 * implementation issue in the kernel.
-		 */
-		[UDP] = 0,
+		[UDP] = (ETH_RSS_NONFRAG_IPV4_UDP |
+			 ETH_RSS_NONFRAG_IPV6_UDP |
+			 ETH_RSS_IPV6_UDP_EX),
 	};
 	const uint64_t out[RTE_DIM(in)] = {
 		[IPV4] = IBV_RX_HASH_SRC_IPV4 | IBV_RX_HASH_DST_IPV4,
@@ -157,10 +157,12 @@ mlx4_conv_rss_hf(uint64_t rss_hf)
 			seen |= rss_hf & in[i];
 			conv |= out[i];
 		}
-	if (rss_hf == (uint64_t)-1)
-		return conv;
-	if (!(rss_hf & ~seen))
-		return conv;
+	if ((conv & priv->hw_rss_sup) == conv) {
+		if (rss_hf == (uint64_t)-1)
+			return conv;
+		if (!(rss_hf & ~seen))
+			return conv;
+	}
 	rte_errno = ENOTSUP;
 	return (uint64_t)-1;
 }
@@ -803,7 +805,8 @@ mlx4_flow_prepare(struct priv *priv,
 				goto exit_action_not_supported;
 			}
 			flow->rss = mlx4_rss_get
-				(priv, mlx4_conv_rss_hf(rss_conf->rss_hf),
+				(priv,
+				 mlx4_conv_rss_hf(priv, rss_conf->rss_hf),
 				 rss_conf->rss_key, rss->num, rss->queue);
 			if (!flow->rss) {
 				msg = "either invalid parameters or not enough"
diff --git a/drivers/net/mlx4/mlx4_flow.h b/drivers/net/mlx4/mlx4_flow.h
index 651fd37..b10c4f5 100644
--- a/drivers/net/mlx4/mlx4_flow.h
+++ b/drivers/net/mlx4/mlx4_flow.h
@@ -75,6 +75,7 @@ struct rte_flow {
 
 /* mlx4_flow.c */
 
+uint64_t mlx4_conv_rss_hf(struct priv *priv, uint64_t rss_hf);
 int mlx4_flow_sync(struct priv *priv, struct rte_flow_error *error);
 void mlx4_flow_clean(struct priv *priv);
 int mlx4_filter_ctrl(struct rte_eth_dev *dev,
-- 
2.1.4