> Track and expose per-device XDP statistics via ethtool, covering both
> the RX and TX sides of the XDP data path.
> 
> A new struct airoha_xdp_stats is introduced and embedded in the existing
> struct airoha_hw_stats. It contains the following counters, all protected
> by the existing u64_stats_sync:
> 
>   rx_xdp_pass            - frames passed to the networking stack
>   rx_xdp_aborted         - frames with XDP_ABORTED or unknown action
>   rx_xdp_drop            - frames dropped by the BPF program or on error
>   rx_xdp_tx              - frames sent back out via XDP_TX
>   rx_xdp_tx_errors       - XDP_TX failures
>   rx_xdp_redirect        - frames successfully redirected
>   rx_xdp_redirect_errors - XDP_REDIRECT failures
>   tx_xdp_xmit            - frames successfully submitted via ndo_xdp_xmit
>   tx_xdp_xmit_errors     - frames dropped in ndo_xdp_xmit
> 
> The airoha_run_xdp() function is reworked to update the appropriate
> counter after each XDP action. The airoha_xdp_xmit() ndo_xdp_xmit handler
> is updated to record the number of successfully transmitted and dropped
> frames.
> 
> The ethtool interface is extended with three new callbacks:
> 
> - get_strings: emits the XDP counter names followed by the page pool
>   stat strings obtained from page_pool_ethtool_stats_get_strings().
> - get_sset_count: returns the combined count of XDP and page pool stats.
> - get_ethtool_stats: reads the XDP counters under the u64_stats_sync
>   seqcount and appends page pool stats collected from all active RX
>   queues via page_pool_get_stats().
> 
> PAGE_POOL_STATS is selected in Kconfig to enable the page pool statistics
> infrastructure required by the ethtool callbacks.
> 
> Signed-off-by: Til Kaiser <mail@tk154.de>
> ---
>  drivers/net/ethernet/airoha/Kconfig      |   1 +
>  drivers/net/ethernet/airoha/airoha_eth.c | 131 ++++++++++++++++++++---
>  drivers/net/ethernet/airoha/airoha_eth.h |  14 +++
>  3 files changed, 133 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/net/ethernet/airoha/Kconfig b/drivers/net/ethernet/airoha/Kconfig
> index 1f6640a15fc9..3fa7683a79e9 100644
> --- a/drivers/net/ethernet/airoha/Kconfig
> +++ b/drivers/net/ethernet/airoha/Kconfig
> @@ -20,6 +20,7 @@ config NET_AIROHA
>  	depends on NET_DSA || !NET_DSA
>  	select NET_AIROHA_NPU
>  	select PAGE_POOL
> +	select PAGE_POOL_STATS
>  	help
>  	  This driver supports the gigabit ethernet MACs in the
>  	  Airoha SoC family.
> diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c
> index 71b25f225a8a..29b837204842 100644
> --- a/drivers/net/ethernet/airoha/airoha_eth.c
> +++ b/drivers/net/ethernet/airoha/airoha_eth.c
> @@ -864,6 +864,11 @@ static int airoha_xdp_xmit(struct net_device *netdev, int n,
>  	spin_unlock(&q->lock);
>  	rcu_read_unlock();
>  
> +	u64_stats_update_begin(&dev->stats.syncp);
> +	dev->stats.xdp_stats.tx_xdp_xmit += n - drops;
> +	dev->stats.xdp_stats.tx_xdp_xmit_errors += drops;
> +	u64_stats_update_end(&dev->stats.syncp);
> +
>  	return n - drops;
>  }
>  
> @@ -871,40 +876,56 @@ static bool airoha_run_xdp(struct net_device *netdev, struct bpf_prog *prog,
>  			   struct xdp_buff *xdp, struct airoha_queue *q,
>  			   struct airoha_queue_entry *e, struct page *page)
>  {
> +	struct airoha_gdm_dev *dev = netdev_priv(netdev);
> +	struct airoha_hw_stats *hw_stats = &dev->stats;
>  	u32 act = bpf_prog_run_xdp(prog, xdp);
> +	u64 *count;
>  
>  	switch (act) {
>  	case XDP_PASS:
> -		return false;
> +		count = &hw_stats->xdp_stats.rx_xdp_pass;
> +		goto update_stats;
>  	case XDP_TX:
>  		if (unlikely(airoha_xdp_xmit_back(netdev, xdp, q->qdma) < 0)) {
> +			count = &hw_stats->xdp_stats.rx_xdp_tx_errors;
>  			trace_xdp_exception(netdev, prog, act);
> -			page_pool_put_full_page(q->page_pool, page, true);
> -		} else {
> -			e->buf = NULL;
> +			break;
>  		}
> -		break;
> +
> +		e->buf = NULL;
> +		count = &hw_stats->xdp_stats.rx_xdp_tx;
> +		goto update_stats;
>  	case XDP_REDIRECT:
>  		if (unlikely(xdp_do_redirect(netdev, xdp, prog) < 0)) {
> +			count = &hw_stats->xdp_stats.rx_xdp_redirect_errors;
>  			trace_xdp_exception(netdev, prog, act);
> -			page_pool_put_full_page(q->page_pool, page, true);
> -		} else {
> -			q->xdp_flush = true;
> -			e->buf = NULL;
> +			break;
>  		}
> -		break;
> +
> +		e->buf = NULL;
> +		q->xdp_flush = true;
> +		count = &hw_stats->xdp_stats.rx_xdp_redirect;
> +		goto update_stats;
>  	default:
>  		bpf_warn_invalid_xdp_action(netdev, prog, act);
>  		fallthrough;
>  	case XDP_ABORTED:
> +		count = &hw_stats->xdp_stats.rx_xdp_aborted;
>  		trace_xdp_exception(netdev, prog, act);
> -		fallthrough;
> +		break;
>  	case XDP_DROP:
> -		page_pool_put_full_page(q->page_pool, page, true);
> +		count = &hw_stats->xdp_stats.rx_xdp_drop;
>  		break;
>  	}
>  
> -	return true;
> +	page_pool_put_full_page(q->page_pool, page, true);
> +
> +update_stats:
> +	u64_stats_update_begin(&hw_stats->syncp);
> +	*count = *count + 1;
> +	u64_stats_update_end(&hw_stats->syncp);

Would it better if we update the stats in airoha_qdma_rx_process() passing a
airoha_xdp_stats struct to airoha_run_xdp(). I guess doing so we can even drop
xdp_flush field in airoha_qdma_queue struct.

> +
> +	return act != XDP_PASS;
>  }
>  
>  static int airoha_qdma_rx_process(struct airoha_queue *q, int budget)
> @@ -3676,12 +3697,96 @@ static const struct net_device_ops airoha_netdev_ops = {
>  	.ndo_xdp_xmit		= airoha_xdp_xmit,
>  };
>  
> +#define AIROHA_ETHTOOL_XDP_STAT(x) { #x, \
> +				  offsetof(struct airoha_hw_stats, xdp_stats.x) / \
> +				  sizeof(u64) }
> +
> +static const struct {
> +	const char name[ETH_GSTRING_LEN];
> +	u32 offset;
> +} airoha_ethtool_xdp_stats[] = {
> +	AIROHA_ETHTOOL_XDP_STAT(rx_xdp_redirect),
> +	AIROHA_ETHTOOL_XDP_STAT(rx_xdp_redirect_errors),
> +	AIROHA_ETHTOOL_XDP_STAT(rx_xdp_pass),
> +	AIROHA_ETHTOOL_XDP_STAT(rx_xdp_aborted),
> +	AIROHA_ETHTOOL_XDP_STAT(rx_xdp_drop),
> +	AIROHA_ETHTOOL_XDP_STAT(rx_xdp_tx),
> +	AIROHA_ETHTOOL_XDP_STAT(rx_xdp_tx_errors),
> +	AIROHA_ETHTOOL_XDP_STAT(tx_xdp_xmit),
> +	AIROHA_ETHTOOL_XDP_STAT(tx_xdp_xmit_errors),
> +};
> +
> +static void airoha_ethtool_get_strings(struct net_device *netdev, u32 stringset, u8 *data)

nit I like old style :)

	static void airoha_ethtool_get_strings(struct net_device *netdev,
					       u32 stringset, u8 *data)
	{
		....
	}

> +{
> +	int i;
> +
> +	switch (stringset) {
> +	case ETH_SS_STATS:
> +		for (i = 0; i < ARRAY_SIZE(airoha_ethtool_xdp_stats); i++) {
> +			strscpy(data, airoha_ethtool_xdp_stats[i].name, ETH_GSTRING_LEN);
> +			data += ETH_GSTRING_LEN;
> +		}
> +		page_pool_ethtool_stats_get_strings(data);
> +		break;
> +	}
> +}
> +
> +static int airoha_ethtool_get_sset_count(struct net_device *netdev, int stringset)
> +{
> +	switch (stringset) {
> +	case ETH_SS_STATS:
> +		return ARRAY_SIZE(airoha_ethtool_xdp_stats) + page_pool_ethtool_stats_get_count();

same here:
		return ARRAY_SIZE(airoha_ethtool_xdp_stats) +
		       page_pool_ethtool_stats_get_count();

> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static void airoha_ethtool_get_ethtool_stats(struct net_device *netdev,
> +					     struct ethtool_stats *stats,
> +					     u64 *data)
> +{
> +	struct airoha_gdm_dev *dev = netdev_priv(netdev);
> +	struct airoha_hw_stats *hw_stats = &dev->stats;
> +	u64 *hw_stats_base = (u64 *)hw_stats;
> +	struct page_pool_stats pp_stats = {};
> +	struct airoha_qdma *qdma;
> +	unsigned int start;
> +	int i;
> +
> +	if (netif_running(netdev))
> +		airoha_update_hw_stats(dev);
> +
> +	do {
> +		start = u64_stats_fetch_begin(&hw_stats->syncp);
> +		for (i = 0; i < ARRAY_SIZE(airoha_ethtool_xdp_stats); i++)
> +			data[i] = hw_stats_base[airoha_ethtool_xdp_stats[i].offset];
> +	} while (u64_stats_fetch_retry(&hw_stats->syncp, start));
> +
> +	rcu_read_lock();
> +	qdma = rcu_dereference(dev->qdma);

IIRC airoha_ethtool_get_ethtool_stats() is running under RTNL so you can just
use airoha_qdma_deref() here.

Regards,
Lorenzo

> +	if (qdma) {
> +		for (i = 0; i < ARRAY_SIZE(qdma->q_rx); i++) {
> +			struct airoha_queue *q = &qdma->q_rx[i];
> +
> +			if (q->page_pool)
> +				page_pool_get_stats(q->page_pool, &pp_stats);
> +		}
> +	}
> +	rcu_read_unlock();
> +
> +	page_pool_ethtool_stats_get(data + ARRAY_SIZE(airoha_ethtool_xdp_stats),
> +				    &pp_stats);
> +}
> +
>  static const struct ethtool_ops airoha_ethtool_ops = {
>  	.get_drvinfo		= airoha_ethtool_get_drvinfo,
>  	.get_eth_mac_stats      = airoha_ethtool_get_mac_stats,
>  	.get_rmon_stats		= airoha_ethtool_get_rmon_stats,
>  	.get_link_ksettings	= phy_ethtool_get_link_ksettings,
>  	.get_link		= ethtool_op_get_link,
> +	.get_strings		= airoha_ethtool_get_strings,
> +	.get_sset_count		= airoha_ethtool_get_sset_count,
> +	.get_ethtool_stats	= airoha_ethtool_get_ethtool_stats,
>  };
>  
>  static int airoha_metadata_dst_alloc(struct airoha_gdm_port *port)
> diff --git a/drivers/net/ethernet/airoha/airoha_eth.h b/drivers/net/ethernet/airoha/airoha_eth.h
> index cfbc0b8f5bf9..d2ac295c49e9 100644
> --- a/drivers/net/ethernet/airoha/airoha_eth.h
> +++ b/drivers/net/ethernet/airoha/airoha_eth.h
> @@ -236,6 +236,18 @@ struct airoha_tx_irq_queue {
>  	u32 *q;
>  };
>  
> +struct airoha_xdp_stats {
> +	u64 rx_xdp_redirect;
> +	u64 rx_xdp_redirect_errors;
> +	u64 rx_xdp_pass;
> +	u64 rx_xdp_aborted;
> +	u64 rx_xdp_drop;
> +	u64 rx_xdp_tx;
> +	u64 rx_xdp_tx_errors;
> +	u64 tx_xdp_xmit;
> +	u64 tx_xdp_xmit_errors;
> +};
> +
>  struct airoha_hw_stats {
>  	struct u64_stats_sync syncp;
>  
> @@ -259,6 +271,8 @@ struct airoha_hw_stats {
>  	u64 rx_jabber;
>  	u64 rx_len[7];
>  
> +	struct airoha_xdp_stats xdp_stats;
> +
>  	struct {
>  		/* Previous HW register values for 32-bit counter delta
>  		 * tracking. Storing the last seen value and accumulating
> -- 
> 2.55.0
> 
>