Subject: Re: [RFC bpf-next 06/23] ice: Support HW timestamp hint

From: Maciej Fijalkowski <[email-masked]>
Date: Mon, 4 Sep 2023 17:38:45 +0200

On Thu, Aug 24, 2023 at 09:26:45PM +0200, Larysa Zaremba wrote:
> Use previously refactored code and create a function
> that allows XDP code to read HW timestamp.
> 
> Also, move cached_phctime into packet context, this way this data still
> stays in the ring structure, just at the different address.
> 
> HW timestamp is the first supported hint in the driver,
> so also add xdp_metadata_ops.
> 
> Signed-off-by: Larysa Zaremba <[email-masked]>
> ---
>  drivers/net/ethernet/intel/ice/ice.h          |  2 ++
>  drivers/net/ethernet/intel/ice/ice_ethtool.c  |  2 +-
>  drivers/net/ethernet/intel/ice/ice_lib.c      |  2 +-
>  drivers/net/ethernet/intel/ice/ice_main.c     |  1 +
>  drivers/net/ethernet/intel/ice/ice_ptp.c      |  3 ++-
>  drivers/net/ethernet/intel/ice/ice_txrx.h     |  2 +-
>  drivers/net/ethernet/intel/ice/ice_txrx_lib.c | 26 ++++++++++++++++++-
>  7 files changed, 33 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice.h b/drivers/net/ethernet/intel/ice/ice.h
> index 5ac0ad12f9f1..34e4731b5d5f 100644
> --- a/drivers/net/ethernet/intel/ice/ice.h
> +++ b/drivers/net/ethernet/intel/ice/ice.h
> @@ -951,4 +951,6 @@ static inline void ice_clear_rdma_cap(struct ice_pf *pf)
>  	set_bit(ICE_FLAG_UNPLUG_AUX_DEV, pf->flags);
>  	clear_bit(ICE_FLAG_RDMA_ENA, pf->flags);
>  }
> +
> +extern const struct xdp_metadata_ops ice_xdp_md_ops;
>  #endif /* _ICE_H_ */
> diff --git a/drivers/net/ethernet/intel/ice/ice_ethtool.c b/drivers/net/ethernet/intel/ice/ice_ethtool.c
> index ad4d4702129f..f740e0ad0e3c 100644
> --- a/drivers/net/ethernet/intel/ice/ice_ethtool.c
> +++ b/drivers/net/ethernet/intel/ice/ice_ethtool.c
> @@ -2846,7 +2846,7 @@ ice_set_ringparam(struct net_device *netdev, struct ethtool_ringparam *ring,
>  		/* clone ring and setup updated count */
>  		rx_rings[i] = *vsi->rx_rings[i];
>  		rx_rings[i].count = new_rx_cnt;
> -		rx_rings[i].cached_phctime = pf->ptp.cached_phc_time;
> +		rx_rings[i].pkt_ctx.cached_phctime = pf->ptp.cached_phc_time;
>  		rx_rings[i].desc = NULL;
>  		rx_rings[i].rx_buf = NULL;
>  		/* this is to allow wr32 to have something to write to
> diff --git a/drivers/net/ethernet/intel/ice/ice_lib.c b/drivers/net/ethernet/intel/ice/ice_lib.c
> index 927518fcad51..12290defb730 100644
> --- a/drivers/net/ethernet/intel/ice/ice_lib.c
> +++ b/drivers/net/ethernet/intel/ice/ice_lib.c
> @@ -1445,7 +1445,7 @@ static int ice_vsi_alloc_rings(struct ice_vsi *vsi)
>  		ring->netdev = vsi->netdev;
>  		ring->dev = dev;
>  		ring->count = vsi->num_rx_desc;
> -		ring->cached_phctime = pf->ptp.cached_phc_time;
> +		ring->pkt_ctx.cached_phctime = pf->ptp.cached_phc_time;
>  		WRITE_ONCE(vsi->rx_rings[i], ring);
>  	}
>  
> diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
> index 0f04347eda39..557c6326ff87 100644
> --- a/drivers/net/ethernet/intel/ice/ice_main.c
> +++ b/drivers/net/ethernet/intel/ice/ice_main.c
> @@ -3395,6 +3395,7 @@ static void ice_set_ops(struct ice_vsi *vsi)
>  
>  	netdev->netdev_ops = &ice_netdev_ops;
>  	netdev->udp_tunnel_nic_info = &pf->hw.udp_tunnel_nic;
> +	netdev->xdp_metadata_ops = &ice_xdp_md_ops;
>  	ice_set_ethtool_ops(netdev);
>  
>  	if (vsi->type != ICE_VSI_PF)
> diff --git a/drivers/net/ethernet/intel/ice/ice_ptp.c b/drivers/net/ethernet/intel/ice/ice_ptp.c
> index a31333972c68..26fad7038996 100644
> --- a/drivers/net/ethernet/intel/ice/ice_ptp.c
> +++ b/drivers/net/ethernet/intel/ice/ice_ptp.c
> @@ -1038,7 +1038,8 @@ static int ice_ptp_update_cached_phctime(struct ice_pf *pf)
>  		ice_for_each_rxq(vsi, j) {
>  			if (!vsi->rx_rings[j])
>  				continue;
> -			WRITE_ONCE(vsi->rx_rings[j]->cached_phctime, systime);
> +			WRITE_ONCE(vsi->rx_rings[j]->pkt_ctx.cached_phctime,
> +				   systime);
>  		}
>  	}
>  	clear_bit(ICE_CFG_BUSY, pf->state);
> diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.h b/drivers/net/ethernet/intel/ice/ice_txrx.h
> index d0ab2c4c0c91..4237702a58a9 100644
> --- a/drivers/net/ethernet/intel/ice/ice_txrx.h
> +++ b/drivers/net/ethernet/intel/ice/ice_txrx.h
> @@ -259,6 +259,7 @@ enum ice_rx_dtype {
>  
>  struct ice_pkt_ctx {
>  	const union ice_32b_rx_flex_desc *eop_desc;
> +	u64 cached_phctime;
>  };
>  
>  struct ice_xdp_buff {
> @@ -354,7 +355,6 @@ struct ice_rx_ring {
>  	struct ice_tx_ring *xdp_ring;
>  	struct xsk_buff_pool *xsk_pool;
>  	dma_addr_t dma;			/* physical address of ring */
> -	u64 cached_phctime;
>  	u16 rx_buf_len;
>  	u8 dcb_tc;			/* Traffic class of ring */
>  	u8 ptp_rx;
> diff --git a/drivers/net/ethernet/intel/ice/ice_txrx_lib.c b/drivers/net/ethernet/intel/ice/ice_txrx_lib.c
> index 07241f4229b7..463d9e5cbe05 100644
> --- a/drivers/net/ethernet/intel/ice/ice_txrx_lib.c
> +++ b/drivers/net/ethernet/intel/ice/ice_txrx_lib.c
> @@ -233,7 +233,7 @@ ice_ptp_rx_hwts_to_skb(struct ice_rx_ring *rx_ring,
>  {
>  	u64 ts_ns, cached_time;
>  
> -	cached_time = READ_ONCE(rx_ring->cached_phctime);
> +	cached_time = READ_ONCE(rx_ring->pkt_ctx.cached_phctime);
>  	ts_ns = ice_ptp_get_rx_hwts(rx_desc, cached_time);
>  
>  	*skb_hwtstamps(skb) = (struct skb_shared_hwtstamps){
> @@ -546,3 +546,27 @@ void ice_finalize_xdp_rx(struct ice_tx_ring *xdp_ring, unsigned int xdp_res,
>  			spin_unlock(&xdp_ring->tx_lock);
>  	}
>  }
> +
> +/**
> + * ice_xdp_rx_hw_ts - HW timestamp XDP hint handler
> + * @ctx: XDP buff pointer
> + * @ts_ns: destination address
> + *
> + * Copy HW timestamp (if available) to the destination address.
> + */
> +static int ice_xdp_rx_hw_ts(const struct xdp_md *ctx, u64 *ts_ns)
> +{
> +	const struct ice_xdp_buff *xdp_ext = (void *)ctx;
> +	u64 cached_time;
> +
> +	cached_time = READ_ONCE(xdp_ext->pkt_ctx.cached_phctime);
> +	*ts_ns = ice_ptp_get_rx_hwts(xdp_ext->pkt_ctx.eop_desc, cached_time);

having cached_phctime within pkt_ctx doesn't stop skb side from using it
right? so again, why note read it within ice_ptp_get_rx_hwts.

> +	if (!*ts_ns)
> +		return -ENODATA;
> +
> +	return 0;
> +}
> +
> +const struct xdp_metadata_ops ice_xdp_md_ops = {
> +	.xmo_rx_timestamp		= ice_xdp_rx_hw_ts,
> +};
> -- 
> 2.41.0
> 
>