[PATCH V5 4/5] bnxt_en: Add TPH support in BNXT driver

[Wei Huang <wei.huang2@amd.com>]

From: Manoj Panicker <manoj.panicker2@amd.com>

Implement TPH support in Broadcom BNXT device driver. The driver uses TPH
functions to retrieve and configure the device's Steering Tags when its
interrupt affinity is being changed. With appropriate firmware, we see
sustancial memory bandwidth savings and other benefits using real network
benchmarks.

Co-developed-by: Somnath Kotur <somnath.kotur@broadcom.com>
Signed-off-by: Somnath Kotur <somnath.kotur@broadcom.com>
Co-developed-by: Wei Huang <wei.huang2@amd.com>
Signed-off-by: Wei Huang <wei.huang2@amd.com>
Signed-off-by: Manoj Panicker <manoj.panicker2@amd.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 85 +++++++++++++++++++++++
 drivers/net/ethernet/broadcom/bnxt/bnxt.h |  7 ++
 net/core/netdev_rx_queue.c                |  1 +
 3 files changed, 93 insertions(+)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 6e422e24750a..ea0bd25d1efb 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -55,6 +55,8 @@
 #include <net/page_pool/helpers.h>
 #include <linux/align.h>
 #include <net/netdev_queues.h>
+#include <net/netdev_rx_queue.h>
+#include <linux/pci-tph.h>
 
 #include "bnxt_hsi.h"
 #include "bnxt.h"
@@ -10865,6 +10867,63 @@ int bnxt_reserve_rings(struct bnxt *bp, bool irq_re_init)
 	return 0;
 }
 
+static void __bnxt_irq_affinity_notify(struct irq_affinity_notify *notify,
+				       const cpumask_t *mask)
+{
+	struct bnxt_rx_ring_info *rxr;
+	struct bnxt_irq *irq;
+	u16 tag;
+	int err;
+
+	irq = container_of(notify, struct bnxt_irq, affinity_notify);
+	cpumask_copy(irq->cpu_mask, mask);
+
+	if (pcie_tph_get_cpu_st(irq->bp->pdev, TPH_MEM_TYPE_VM,
+				cpumask_first(irq->cpu_mask), &tag))
+		return;
+
+	if (pcie_tph_set_st_entry(irq->bp->pdev, irq->msix_nr, tag))
+		return;
+
+	if (netif_running(irq->bp->dev)) {
+		rxr = &irq->bp->rx_ring[irq->ring_nr];
+		rtnl_lock();
+		err = netdev_rx_queue_restart(irq->bp->dev, irq->ring_nr);
+		if (err)
+			netdev_err(irq->bp->dev,
+				   "rx queue restart failed: err=%d\n", err);
+		rtnl_unlock();
+	}
+}
+
+static void __bnxt_irq_affinity_release(struct kref __always_unused *ref)
+{
+}
+
+static void bnxt_release_irq_notifier(struct bnxt_irq *irq)
+{
+	irq_set_affinity_notifier(irq->vector, NULL);
+}
+
+static void bnxt_register_irq_notifier(struct bnxt *bp, struct bnxt_irq *irq)
+{
+	struct irq_affinity_notify *notify;
+
+	/* Nothing to do if TPH is not enabled */
+	if (!bp->tph_mode)
+		return;
+
+	irq->bp = bp;
+
+	/* Register IRQ affinity notifier */
+	notify = &irq->affinity_notify;
+	notify->irq = irq->vector;
+	notify->notify = __bnxt_irq_affinity_notify;
+	notify->release = __bnxt_irq_affinity_release;
+
+	irq_set_affinity_notifier(irq->vector, notify);
+}
+
 static void bnxt_free_irq(struct bnxt *bp)
 {
 	struct bnxt_irq *irq;
@@ -10887,11 +10946,18 @@ static void bnxt_free_irq(struct bnxt *bp)
 				free_cpumask_var(irq->cpu_mask);
 				irq->have_cpumask = 0;
 			}
+
+			bnxt_release_irq_notifier(irq);
+
 			free_irq(irq->vector, bp->bnapi[i]);
 		}
 
 		irq->requested = 0;
 	}
+
+	/* Disable TPH support */
+	pcie_disable_tph(bp->pdev);
+	bp->tph_mode = 0;
 }
 
 static int bnxt_request_irq(struct bnxt *bp)
@@ -10911,6 +10977,12 @@ static int bnxt_request_irq(struct bnxt *bp)
 #ifdef CONFIG_RFS_ACCEL
 	rmap = bp->dev->rx_cpu_rmap;
 #endif
+
+	/* Enable TPH support as part of IRQ request */
+	rc = pcie_enable_tph(bp->pdev, PCI_TPH_ST_IV_MODE);
+	if (!rc)
+		bp->tph_mode = PCI_TPH_ST_IV_MODE;
+
 	for (i = 0, j = 0; i < bp->cp_nr_rings; i++) {
 		int map_idx = bnxt_cp_num_to_irq_num(bp, i);
 		struct bnxt_irq *irq = &bp->irq_tbl[map_idx];
@@ -10934,8 +11006,11 @@ static int bnxt_request_irq(struct bnxt *bp)
 
 		if (zalloc_cpumask_var(&irq->cpu_mask, GFP_KERNEL)) {
 			int numa_node = dev_to_node(&bp->pdev->dev);
+			u16 tag;
 
 			irq->have_cpumask = 1;
+			irq->msix_nr = map_idx;
+			irq->ring_nr = i;
 			cpumask_set_cpu(cpumask_local_spread(i, numa_node),
 					irq->cpu_mask);
 			rc = irq_set_affinity_hint(irq->vector, irq->cpu_mask);
@@ -10945,6 +11020,16 @@ static int bnxt_request_irq(struct bnxt *bp)
 					    irq->vector);
 				break;
 			}
+
+			bnxt_register_irq_notifier(bp, irq);
+
+			/* Init ST table entry */
+			if (pcie_tph_get_cpu_st(irq->bp->pdev, TPH_MEM_TYPE_VM,
+						cpumask_first(irq->cpu_mask),
+						&tag))
+				continue;
+
+			pcie_tph_set_st_entry(irq->bp->pdev, irq->msix_nr, tag);
 		}
 	}
 	return rc;
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
index 69231e85140b..641d25646367 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
@@ -1227,6 +1227,11 @@ struct bnxt_irq {
 	u8		have_cpumask:1;
 	char		name[IFNAMSIZ + BNXT_IRQ_NAME_EXTRA];
 	cpumask_var_t	cpu_mask;
+
+	struct bnxt	*bp;
+	int		msix_nr;
+	int		ring_nr;
+	struct irq_affinity_notify affinity_notify;
 };
 
 #define HWRM_RING_ALLOC_TX	0x1
@@ -2183,6 +2188,8 @@ struct bnxt {
 	struct net_device	*dev;
 	struct pci_dev		*pdev;
 
+	u8			tph_mode;
+
 	atomic_t		intr_sem;
 
 	u32			flags;
diff --git a/net/core/netdev_rx_queue.c b/net/core/netdev_rx_queue.c
index e217a5838c87..10e95d7b6892 100644
--- a/net/core/netdev_rx_queue.c
+++ b/net/core/netdev_rx_queue.c
@@ -79,3 +79,4 @@ int netdev_rx_queue_restart(struct net_device *dev, unsigned int rxq_idx)
 
 	return err;
 }
+EXPORT_SYMBOL_GPL(netdev_rx_queue_restart);
-- 
2.45.1