linux-kernel - Re: [PATCH V1 8/9] bnxt_en: Add TPH support in BNXT driver

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Message-ID: <868a4758-2873-4ede-83e5-65f42cb12b81@linux.dev>
Date: Thu, 9 May 2024 22:50:46 +0100
From: Vadim Fedorenko <vadim.fedorenko@...ux.dev>
To: Wei Huang <wei.huang2@....com>, linux-pci@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
 netdev@...r.kernel.org
Cc: bhelgaas@...gle.com, corbet@....net, davem@...emloft.net,
 edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
 alex.williamson@...hat.com, gospo@...adcom.com, michael.chan@...adcom.com,
 ajit.khaparde@...adcom.com, manoj.panicker2@....com, Eric.VanTassell@....com
Subject: Re: [PATCH V1 8/9] bnxt_en: Add TPH support in BNXT driver

On 09/05/2024 17:27, Wei Huang wrote:
> From: Manoj Panicker <manoj.panicker2@....com>
> 
> As a usage example, this patch implements TPH support in Broadcom BNXT
> device driver by invoking pcie_tph_set_st() function when interrupt
> affinity is changed.
> 
> Reviewed-by: Ajit Khaparde <ajit.khaparde@...adcom.com>
> Reviewed-by: Andy Gospodarek <andrew.gospodarek@...adcom.com>
> Reviewed-by: Wei Huang <wei.huang2@....com>
> Signed-off-by: Manoj Panicker <manoj.panicker2@....com>
> ---
>   drivers/net/ethernet/broadcom/bnxt/bnxt.c | 51 +++++++++++++++++++++++
>   drivers/net/ethernet/broadcom/bnxt/bnxt.h |  4 ++
>   2 files changed, 55 insertions(+)
> 
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> index 2c2ee79c4d77..be9c17566fb4 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> @@ -55,6 +55,7 @@
>   #include <net/page_pool/helpers.h>
>   #include <linux/align.h>
>   #include <net/netdev_queues.h>
> +#include <linux/pci-tph.h>
>   
>   #include "bnxt_hsi.h"
>   #include "bnxt.h"
> @@ -10491,6 +10492,7 @@ static void bnxt_free_irq(struct bnxt *bp)
>   				free_cpumask_var(irq->cpu_mask);
>   				irq->have_cpumask = 0;
>   			}
> +			irq_set_affinity_notifier(irq->vector, NULL);
>   			free_irq(irq->vector, bp->bnapi[i]);
>   		}
>   
> @@ -10498,6 +10500,45 @@ static void bnxt_free_irq(struct bnxt *bp)
>   	}
>   }
>   
> +static void bnxt_rtnl_lock_sp(struct bnxt *bp);
> +static void bnxt_rtnl_unlock_sp(struct bnxt *bp);
> +static void bnxt_irq_affinity_notify(struct irq_affinity_notify *notify,
> +				     const cpumask_t *mask)
> +{
> +	struct bnxt_irq *irq;
> +
> +	irq = container_of(notify, struct bnxt_irq, affinity_notify);
> +	cpumask_copy(irq->cpu_mask, mask);
> +
> +	if (!pcie_tph_set_st(irq->bp->pdev, irq->msix_nr,
> +			     cpumask_first(irq->cpu_mask),
> +			     TPH_MEM_TYPE_VM, PCI_TPH_REQ_TPH_ONLY))
> +		pr_err("error in configuring steering tag\n");
> +
> +	if (netif_running(irq->bp->dev)) {
> +		rtnl_lock();
> +		bnxt_close_nic(irq->bp, false, false);
> +		bnxt_open_nic(irq->bp, false, false);
> +		rtnl_unlock();
> +	}

Is it really needed? It will cause link flap and pause in the traffic
service for the device. Why the device needs full restart in this case?

> +}
> +
> +static void bnxt_irq_affinity_release(struct kref __always_unused *ref)
> +{
> +}
> +
> +static inline void __bnxt_register_notify_irqchanges(struct bnxt_irq *irq)

No inlines in .c files, please. Let compiler decide what to inline.

> +{
> +	struct irq_affinity_notify *notify;
> +
> +	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 int bnxt_request_irq(struct bnxt *bp)
>   {
>   	int i, j, rc = 0;
> @@ -10543,6 +10584,7 @@ static int bnxt_request_irq(struct bnxt *bp)
>   			int numa_node = dev_to_node(&bp->pdev->dev);
>   
>   			irq->have_cpumask = 1;
> +			irq->msix_nr = map_idx;
>   			cpumask_set_cpu(cpumask_local_spread(i, numa_node),
>   					irq->cpu_mask);
>   			rc = irq_set_affinity_hint(irq->vector, irq->cpu_mask);
> @@ -10552,6 +10594,15 @@ static int bnxt_request_irq(struct bnxt *bp)
>   					    irq->vector);
>   				break;
>   			}
> +
> +			if (!pcie_tph_set_st(bp->pdev, i,
> +					     cpumask_first(irq->cpu_mask),
> +					     TPH_MEM_TYPE_VM, PCI_TPH_REQ_TPH_ONLY)) {
> +				netdev_err(bp->dev, "error in setting steering tag\n");
> +			} else {
> +				irq->bp = bp;
> +				__bnxt_register_notify_irqchanges(irq);
> +			}
>   		}
>   	}
>   	return rc;
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
> index dd849e715c9b..0d3442590bb4 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
> @@ -1195,6 +1195,10 @@ struct bnxt_irq {
>   	u8		have_cpumask:1;
>   	char		name[IFNAMSIZ + 2];
>   	cpumask_var_t	cpu_mask;
> +
> +	int		msix_nr;
> +	struct bnxt	*bp;
> +	struct irq_affinity_notify affinity_notify;
>   };
>   
>   #define HWRM_RING_ALLOC_TX	0x1