Merge branch 'net-mlx5e-add-support-for-pcie-congestion-events'

Tariq Toukan says:

====================
net/mlx5e: Add support for PCIe congestion events

Dragos says:

PCIe congestion events are events generated by the firmware when the
device side has sustained PCIe inbound or outbound traffic above
certain thresholds. The high and low threshold are hysteresis thresholds
to prevent flapping: once the high threshold has been reached, a low
threshold event will be triggered only after the bandwidth usage went
below the low threshold.

This series adds support for receiving and exposing such events as
ethtool counters.

2 new pairs of counters are exposed: pci_bw_in/outbound_high/low. These
should help the user understand if the device PCI is under pressure.

Planned followup patches:
- Allow configuration of thresholds through devlink.
- Add ethtool counter for wakeups which did not result in any state
  change.
====================

Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: kuba-moo

Documentation/networking/device_drivers/ethernet/mellanox/mlx5/counters.rst

@@ -1341,3 +1341,35 @@ Device Counters
      - The number of times the device owned queue had not enough buffers
        allocated.
      - Error
+
+   * - `pci_bw_inbound_high`
+     - The number of times the device crossed the high inbound pcie bandwidth
+       threshold. To be compared to pci_bw_inbound_low to check if the device
+       is in a congested state.
+       If pci_bw_inbound_high == pci_bw_inbound_low then the device is not congested.
+       If pci_bw_inbound_high > pci_bw_inbound_low then the device is congested.
+     - Tnformative
+
+   * - `pci_bw_inbound_low`
+     - The number of times the device crossed the low inbound PCIe bandwidth
+       threshold. To be compared to pci_bw_inbound_high to check if the device
+       is in a congested state.
+       If pci_bw_inbound_high == pci_bw_inbound_low then the device is not congested.
+       If pci_bw_inbound_high > pci_bw_inbound_low then the device is congested.
+     - Informative
+
+   * - `pci_bw_outbound_high`
+     - The number of times the device crossed the high outbound pcie bandwidth
+       threshold. To be compared to pci_bw_outbound_low to check if the device
+       is in a congested state.
+       If pci_bw_outbound_high == pci_bw_outbound_low then the device is not congested.
+       If pci_bw_outbound_high > pci_bw_outbound_low then the device is congested.
+     - Informative
+
+   * - `pci_bw_outbound_low`
+     - The number of times the device crossed the low outbound PCIe bandwidth
+       threshold. To be compared to pci_bw_outbound_high to check if the device
+       is in a congested state.
+       If pci_bw_outbound_high == pci_bw_outbound_low then the device is not congested.
+       If pci_bw_outbound_high > pci_bw_outbound_low then the device is congested.
+     - Informative

drivers/net/ethernet/mellanox/mlx5/core/Makefile

@@ -29,7 +29,7 @@ mlx5_core-$(CONFIG_MLX5_CORE_EN) += en/rqt.o en/tir.o en/rss.o en/rx_res.o \
 		en/reporter_tx.o en/reporter_rx.o en/params.o en/xsk/pool.o \
 		en/xsk/setup.o en/xsk/rx.o en/xsk/tx.o en/devlink.o en/ptp.o \
 		en/qos.o en/htb.o en/trap.o en/fs_tt_redirect.o en/selq.o \
-		lib/crypto.o lib/sd.o
+		lib/crypto.o lib/sd.o en/pcie_cong_event.o
 
 #
 # Netdev extra

drivers/net/ethernet/mellanox/mlx5/core/en.h

@@ -920,6 +920,8 @@ struct mlx5e_priv {
 	struct notifier_block      events_nb;
 	struct notifier_block      blocking_events_nb;
 
+	struct mlx5e_pcie_cong_event *cong_event;
+
 	struct udp_tunnel_nic_info nic_info;
 #ifdef CONFIG_MLX5_CORE_EN_DCB
 	struct mlx5e_dcbx          dcbx;

drivers/net/ethernet/mellanox/mlx5/core/en/pcie_cong_event.c

@@ -0,0 +1,315 @@
+// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
+// Copyright (c) 2025, NVIDIA CORPORATION & AFFILIATES.
+
+#include "en.h"
+#include "pcie_cong_event.h"
+
+#define MLX5E_CONG_HIGH_STATE 0x7
+
+enum {
+	MLX5E_INBOUND_CONG  = BIT(0),
+	MLX5E_OUTBOUND_CONG = BIT(1),
+};
+
+struct mlx5e_pcie_cong_thresh {
+	u16 inbound_high;
+	u16 inbound_low;
+	u16 outbound_high;
+	u16 outbound_low;
+};
+
+struct mlx5e_pcie_cong_stats {
+	u32 pci_bw_inbound_high;
+	u32 pci_bw_inbound_low;
+	u32 pci_bw_outbound_high;
+	u32 pci_bw_outbound_low;
+};
+
+struct mlx5e_pcie_cong_event {
+	u64 obj_id;
+
+	struct mlx5e_priv *priv;
+
+	/* For event notifier and workqueue. */
+	struct work_struct work;
+	struct mlx5_nb nb;
+
+	/* Stores last read state. */
+	u8 state;
+
+	/* For ethtool stats group. */
+	struct mlx5e_pcie_cong_stats stats;
+};
+
+/* In units of 0.01 % */
+static const struct mlx5e_pcie_cong_thresh default_thresh_config = {
+	.inbound_high = 9000,
+	.inbound_low = 7500,
+	.outbound_high = 9000,
+	.outbound_low = 7500,
+};
+
+static const struct counter_desc mlx5e_pcie_cong_stats_desc[] = {
+	{ MLX5E_DECLARE_STAT(struct mlx5e_pcie_cong_stats,
+			     pci_bw_inbound_high) },
+	{ MLX5E_DECLARE_STAT(struct mlx5e_pcie_cong_stats,
+			     pci_bw_inbound_low) },
+	{ MLX5E_DECLARE_STAT(struct mlx5e_pcie_cong_stats,
+			     pci_bw_outbound_high) },
+	{ MLX5E_DECLARE_STAT(struct mlx5e_pcie_cong_stats,
+			     pci_bw_outbound_low) },
+};
+
+#define NUM_PCIE_CONG_COUNTERS ARRAY_SIZE(mlx5e_pcie_cong_stats_desc)
+
+static MLX5E_DECLARE_STATS_GRP_OP_NUM_STATS(pcie_cong)
+{
+	return priv->cong_event ? NUM_PCIE_CONG_COUNTERS : 0;
+}
+
+static MLX5E_DECLARE_STATS_GRP_OP_UPDATE_STATS(pcie_cong) {}
+
+static MLX5E_DECLARE_STATS_GRP_OP_FILL_STRS(pcie_cong)
+{
+	if (!priv->cong_event)
+		return;
+
+	for (int i = 0; i < NUM_PCIE_CONG_COUNTERS; i++)
+		ethtool_puts(data, mlx5e_pcie_cong_stats_desc[i].format);
+}
+
+static MLX5E_DECLARE_STATS_GRP_OP_FILL_STATS(pcie_cong)
+{
+	if (!priv->cong_event)
+		return;
+
+	for (int i = 0; i < NUM_PCIE_CONG_COUNTERS; i++) {
+		u32 ctr = MLX5E_READ_CTR32_CPU(&priv->cong_event->stats,
+					       mlx5e_pcie_cong_stats_desc,
+					       i);
+
+		mlx5e_ethtool_put_stat(data, ctr);
+	}
+}
+
+MLX5E_DEFINE_STATS_GRP(pcie_cong, 0);
+
+static int
+mlx5_cmd_pcie_cong_event_set(struct mlx5_core_dev *dev,
+			     const struct mlx5e_pcie_cong_thresh *config,
+			     u64 *obj_id)
+{
+	u32 in[MLX5_ST_SZ_DW(pcie_cong_event_cmd_in)] = {};
+	u32 out[MLX5_ST_SZ_DW(general_obj_out_cmd_hdr)];
+	void *cong_obj;
+	void *hdr;
+	int err;
+
+	hdr = MLX5_ADDR_OF(pcie_cong_event_cmd_in, in, hdr);
+	cong_obj = MLX5_ADDR_OF(pcie_cong_event_cmd_in, in, cong_obj);
+
+	MLX5_SET(general_obj_in_cmd_hdr, hdr, opcode,
+		 MLX5_CMD_OP_CREATE_GENERAL_OBJECT);
+
+	MLX5_SET(general_obj_in_cmd_hdr, hdr, obj_type,
+		 MLX5_GENERAL_OBJECT_TYPES_PCIE_CONG_EVENT);
+
+	MLX5_SET(pcie_cong_event_obj, cong_obj, inbound_event_en, 1);
+	MLX5_SET(pcie_cong_event_obj, cong_obj, outbound_event_en, 1);
+
+	MLX5_SET(pcie_cong_event_obj, cong_obj,
+		 inbound_cong_high_threshold, config->inbound_high);
+	MLX5_SET(pcie_cong_event_obj, cong_obj,
+		 inbound_cong_low_threshold, config->inbound_low);
+
+	MLX5_SET(pcie_cong_event_obj, cong_obj,
+		 outbound_cong_high_threshold, config->outbound_high);
+	MLX5_SET(pcie_cong_event_obj, cong_obj,
+		 outbound_cong_low_threshold, config->outbound_low);
+
+	err = mlx5_cmd_exec(dev, in, sizeof(in), out, sizeof(out));
+	if (err)
+		return err;
+
+	*obj_id = MLX5_GET(general_obj_out_cmd_hdr, out, obj_id);
+
+	mlx5_core_dbg(dev, "PCIe congestion event (obj_id=%llu) created. Config: in: [%u, %u], out: [%u, %u]\n",
+		      *obj_id,
+		      config->inbound_high, config->inbound_low,
+		      config->outbound_high, config->outbound_low);
+
+	return 0;
+}
+
+static int mlx5_cmd_pcie_cong_event_destroy(struct mlx5_core_dev *dev,
+					    u64 obj_id)
+{
+	u32 in[MLX5_ST_SZ_DW(pcie_cong_event_cmd_in)] = {};
+	u32 out[MLX5_ST_SZ_DW(general_obj_out_cmd_hdr)];
+	void *hdr;
+
+	hdr = MLX5_ADDR_OF(pcie_cong_event_cmd_in, in, hdr);
+	MLX5_SET(general_obj_in_cmd_hdr, hdr, opcode,
+		 MLX5_CMD_OP_DESTROY_GENERAL_OBJECT);
+	MLX5_SET(general_obj_in_cmd_hdr, hdr, obj_type,
+		 MLX5_GENERAL_OBJECT_TYPES_PCIE_CONG_EVENT);
+	MLX5_SET(general_obj_in_cmd_hdr, hdr, obj_id, obj_id);
+
+	return mlx5_cmd_exec(dev, in, sizeof(in), out, sizeof(out));
+}
+
+static int mlx5_cmd_pcie_cong_event_query(struct mlx5_core_dev *dev,
+					  u64 obj_id,
+					  u32 *state)
+{
+	u32 in[MLX5_ST_SZ_DW(pcie_cong_event_cmd_in)] = {};
+	u32 out[MLX5_ST_SZ_DW(pcie_cong_event_cmd_out)];
+	void *obj;
+	void *hdr;
+	u8 cong;
+	int err;
+
+	hdr = MLX5_ADDR_OF(pcie_cong_event_cmd_in, in, hdr);
+
+	MLX5_SET(general_obj_in_cmd_hdr, hdr, opcode,
+		 MLX5_CMD_OP_QUERY_GENERAL_OBJECT);
+	MLX5_SET(general_obj_in_cmd_hdr, hdr, obj_type,
+		 MLX5_GENERAL_OBJECT_TYPES_PCIE_CONG_EVENT);
+	MLX5_SET(general_obj_in_cmd_hdr, hdr, obj_id, obj_id);
+
+	err = mlx5_cmd_exec(dev, in, sizeof(in), out, sizeof(out));
+	if (err)
+		return err;
+
+	obj = MLX5_ADDR_OF(pcie_cong_event_cmd_out, out, cong_obj);
+
+	if (state) {
+		cong = MLX5_GET(pcie_cong_event_obj, obj, inbound_cong_state);
+		if (cong == MLX5E_CONG_HIGH_STATE)
+			*state |= MLX5E_INBOUND_CONG;
+
+		cong = MLX5_GET(pcie_cong_event_obj, obj, outbound_cong_state);
+		if (cong == MLX5E_CONG_HIGH_STATE)
+			*state |= MLX5E_OUTBOUND_CONG;
+	}
+
+	return 0;
+}
+
+static void mlx5e_pcie_cong_event_work(struct work_struct *work)
+{
+	struct mlx5e_pcie_cong_event *cong_event;
+	struct mlx5_core_dev *dev;
+	struct mlx5e_priv *priv;
+	u32 new_cong_state = 0;
+	u32 changes;
+	int err;
+
+	cong_event = container_of(work, struct mlx5e_pcie_cong_event, work);
+	priv = cong_event->priv;
+	dev = priv->mdev;
+
+	err = mlx5_cmd_pcie_cong_event_query(dev, cong_event->obj_id,
+					     &new_cong_state);
+	if (err) {
+		mlx5_core_warn(dev, "Error %d when querying PCIe cong event object (obj_id=%llu).\n",
+			       err, cong_event->obj_id);
+		return;
+	}
+
+	changes = cong_event->state ^ new_cong_state;
+	if (!changes)
+		return;
+
+	cong_event->state = new_cong_state;
+
+	if (changes & MLX5E_INBOUND_CONG) {
+		if (new_cong_state & MLX5E_INBOUND_CONG)
+			cong_event->stats.pci_bw_inbound_high++;
+		else
+			cong_event->stats.pci_bw_inbound_low++;
+	}
+
+	if (changes & MLX5E_OUTBOUND_CONG) {
+		if (new_cong_state & MLX5E_OUTBOUND_CONG)
+			cong_event->stats.pci_bw_outbound_high++;
+		else
+			cong_event->stats.pci_bw_outbound_low++;
+	}
+}
+
+static int mlx5e_pcie_cong_event_handler(struct notifier_block *nb,
+					 unsigned long event, void *eqe)
+{
+	struct mlx5e_pcie_cong_event *cong_event;
+
+	cong_event = mlx5_nb_cof(nb, struct mlx5e_pcie_cong_event, nb);
+	queue_work(cong_event->priv->wq, &cong_event->work);
+
+	return NOTIFY_OK;
+}
+
+int mlx5e_pcie_cong_event_init(struct mlx5e_priv *priv)
+{
+	struct mlx5e_pcie_cong_event *cong_event;
+	struct mlx5_core_dev *mdev = priv->mdev;
+	int err;
+
+	if (!mlx5_pcie_cong_event_supported(mdev))
+		return 0;
+
+	cong_event = kvzalloc_node(sizeof(*cong_event), GFP_KERNEL,
+				   mdev->priv.numa_node);
+	if (!cong_event)
+		return -ENOMEM;
+
+	INIT_WORK(&cong_event->work, mlx5e_pcie_cong_event_work);
+	MLX5_NB_INIT(&cong_event->nb, mlx5e_pcie_cong_event_handler,
+		     OBJECT_CHANGE);
+
+	cong_event->priv = priv;
+
+	err = mlx5_cmd_pcie_cong_event_set(mdev, &default_thresh_config,
+					   &cong_event->obj_id);
+	if (err) {
+		mlx5_core_warn(mdev, "Error creating a PCIe congestion event object\n");
+		goto err_free;
+	}
+
+	err = mlx5_eq_notifier_register(mdev, &cong_event->nb);
+	if (err) {
+		mlx5_core_warn(mdev, "Error registering notifier for the PCIe congestion event\n");
+		goto err_obj_destroy;
+	}
+
+	priv->cong_event = cong_event;
+
+	return 0;
+
+err_obj_destroy:
+	mlx5_cmd_pcie_cong_event_destroy(mdev, cong_event->obj_id);
+err_free:
+	kvfree(cong_event);
+
+	return err;
+}
+
+void mlx5e_pcie_cong_event_cleanup(struct mlx5e_priv *priv)
+{
+	struct mlx5e_pcie_cong_event *cong_event = priv->cong_event;
+	struct mlx5_core_dev *mdev = priv->mdev;
+
+	if (!cong_event)
+		return;
+
+	priv->cong_event = NULL;
+
+	mlx5_eq_notifier_unregister(mdev, &cong_event->nb);
+	cancel_work_sync(&cong_event->work);
+
+	if (mlx5_cmd_pcie_cong_event_destroy(mdev, cong_event->obj_id))
+		mlx5_core_warn(mdev, "Error destroying PCIe congestion event (obj_id=%llu)\n",
+			       cong_event->obj_id);
+
+	kvfree(cong_event);
+}

drivers/net/ethernet/mellanox/mlx5/core/en/pcie_cong_event.h

@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
+/* Copyright (c) 2025, NVIDIA CORPORATION & AFFILIATES. */
+
+#ifndef __MLX5_PCIE_CONG_EVENT_H__
+#define __MLX5_PCIE_CONG_EVENT_H__
+
+int mlx5e_pcie_cong_event_init(struct mlx5e_priv *priv);
+void mlx5e_pcie_cong_event_cleanup(struct mlx5e_priv *priv);
+
+#endif /* __MLX5_PCIE_CONG_EVENT_H__ */