[PATCH v2 2/4] net/mlx5: fix real time counter reading from PCI BAR

[Viacheslav Ovsiienko <viacheslavo@nvidia.com>]

From: Tim Martin <timothym@nvidia.com>

There is the mlx5_txpp_read_clock() routine reading
the 64-bit real time counter from the device PCI BAR.
It introduced two issues:

  - it checks the PCI BAR mapping into process address
    space and tries to map this on demand. This might be
    problematic if something goes wrong and mapping fails.
    It happens on every read_clock API call, invokes kernel
    taking a long time and causing application malfunction.

  - the 64-bit counter should be read in single atomic
    transaction

Fixes: 9b31fc9007f9 ("net/mlx5: fix read device clock in real time mode")
Cc: stable@dpdk.org

Signed-off-by: Tim Martin <timothym@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
---
 .mailmap                     |  1 +
 drivers/net/mlx5/mlx5.c      |  4 ++++
 drivers/net/mlx5/mlx5_tx.h   | 34 +++++++++++++++++++++++++++++++++-
 drivers/net/mlx5/mlx5_txpp.c | 11 ++---------
 4 files changed, 40 insertions(+), 10 deletions(-)

diff --git a/.mailmap b/.mailmap
index b30d993f3b..3065211c0a 100644
--- a/.mailmap
+++ b/.mailmap
@@ -1505,6 +1505,7 @@ Timmons C. Player <timmons.player@spirent.com>
 Timothy McDaniel <timothy.mcdaniel@intel.com>
 Timothy Miskell <timothy.miskell@intel.com>
 Timothy Redaelli <tredaelli@redhat.com>
+Tim Martin <timothym@nvidia.com>
 Tim Shearer <tim.shearer@overturenetworks.com>
 Ting-Kai Ku <ting-kai.ku@intel.com>
 Ting Xu <ting.xu@intel.com>
diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
index e36fa651a1..52b90e6ff3 100644
--- a/drivers/net/mlx5/mlx5.c
+++ b/drivers/net/mlx5/mlx5.c
@@ -2242,6 +2242,7 @@ int
 mlx5_proc_priv_init(struct rte_eth_dev *dev)
 {
 	struct mlx5_priv *priv = dev->data->dev_private;
+	struct mlx5_dev_ctx_shared *sh = priv->sh;
 	struct mlx5_proc_priv *ppriv;
 	size_t ppriv_size;
 
@@ -2262,6 +2263,9 @@ mlx5_proc_priv_init(struct rte_eth_dev *dev)
 	dev->process_private = ppriv;
 	if (rte_eal_process_type() == RTE_PROC_PRIMARY)
 		priv->sh->pppriv = ppriv;
+	/* Check and try to map HCA PCI BAR to allow reading real time. */
+	if (sh->dev_cap.rt_timestamp && mlx5_dev_is_pci(dev->device))
+		mlx5_txpp_map_hca_bar(dev);
 	return 0;
 }
 
diff --git a/drivers/net/mlx5/mlx5_tx.h b/drivers/net/mlx5/mlx5_tx.h
index 983913faa2..587e6a9f7d 100644
--- a/drivers/net/mlx5/mlx5_tx.h
+++ b/drivers/net/mlx5/mlx5_tx.h
@@ -372,6 +372,38 @@ mlx5_txpp_convert_tx_ts(struct mlx5_dev_ctx_shared *sh, uint64_t mts)
 	return ci;
 }
 
+/**
+ * Read real time clock counter directly from the device PCI BAR area.
+ * The PCI BAR must be mapped to the process memory space at initialization.
+ *
+ * @param dev
+ *   Device to read clock counter from
+ *
+ * @return
+ *   0 - if HCA BAR is not supported or not mapped.
+ *   !=0 - read 64-bit value of real-time in UTC formatv (nanoseconds)
+ */
+static __rte_always_inline uint64_t mlx5_read_pcibar_clock(struct rte_eth_dev *dev)
+{
+	struct mlx5_proc_priv *ppriv = dev->process_private;
+
+	if (ppriv && ppriv->hca_bar) {
+		struct mlx5_priv *priv = dev->data->dev_private;
+		struct mlx5_dev_ctx_shared *sh = priv->sh;
+		uint64_t *hca_ptr = (uint64_t *)(ppriv->hca_bar) +
+				  __mlx5_64_off(initial_seg, real_time);
+		uint64_t __rte_atomic *ts_addr;
+		uint64_t ts;
+
+		ts_addr = (uint64_t __rte_atomic *)hca_ptr;
+		ts = rte_atomic_load_explicit(ts_addr, rte_memory_order_seq_cst);
+		ts = rte_be_to_cpu_64(ts);
+		ts = mlx5_txpp_convert_rx_ts(sh, ts);
+		return ts;
+	}
+	return 0;
+}
+
 /**
  * Set Software Parser flags and offsets in Ethernet Segment of WQE.
  * Flags must be preliminary initialized to zero.
@@ -822,7 +854,7 @@ mlx5_tx_cseg_init(struct mlx5_txq_data *__rte_restrict txq,
 		cs->flags = RTE_BE32(MLX5_COMP_ONLY_FIRST_ERR <<
 				     MLX5_COMP_MODE_OFFSET);
 	cs->misc = RTE_BE32(0);
-	if (__rte_trace_point_fp_is_enabled() && !loc->pkts_sent)
+	if (__rte_trace_point_fp_is_enabled())
 		rte_pmd_mlx5_trace_tx_entry(txq->port_id, txq->idx);
 	rte_pmd_mlx5_trace_tx_wqe((txq->wqe_ci << 8) | opcode);
 }
diff --git a/drivers/net/mlx5/mlx5_txpp.c b/drivers/net/mlx5/mlx5_txpp.c
index 4e26fa2db8..e6d3ad83e9 100644
--- a/drivers/net/mlx5/mlx5_txpp.c
+++ b/drivers/net/mlx5/mlx5_txpp.c
@@ -971,7 +971,6 @@ mlx5_txpp_read_clock(struct rte_eth_dev *dev, uint64_t *timestamp)
 {
 	struct mlx5_priv *priv = dev->data->dev_private;
 	struct mlx5_dev_ctx_shared *sh = priv->sh;
-	struct mlx5_proc_priv *ppriv;
 	uint64_t ts;
 	int ret;
 
@@ -997,15 +996,9 @@ mlx5_txpp_read_clock(struct rte_eth_dev *dev, uint64_t *timestamp)
 		*timestamp = ts;
 		return 0;
 	}
-	/* Check and try to map HCA PIC BAR to allow reading real time. */
-	ppriv = dev->process_private;
-	if (ppriv && !ppriv->hca_bar &&
-	    sh->dev_cap.rt_timestamp && mlx5_dev_is_pci(dev->device))
-		mlx5_txpp_map_hca_bar(dev);
 	/* Check if we can read timestamp directly from hardware. */
-	if (ppriv && ppriv->hca_bar) {
-		ts = MLX5_GET64(initial_seg, ppriv->hca_bar, real_time);
-		ts = mlx5_txpp_convert_rx_ts(sh, ts);
+	ts = mlx5_read_pcibar_clock(dev);
+	if (ts != 0) {
 		*timestamp = ts;
 		return 0;
 	}
-- 
2.34.1