[PATCH net-next v4 11/33] dpaa2-eth: add XDP frame size

[Jesper Dangaard Brouer <brouer@redhat.com>]

The dpaa2-eth driver reserve some headroom used for hardware and
software annotation area in RX/TX buffers. Thus, xdp.data_hard_start
doesn't start at page boundary.

When XDP is configured the area reserved via dpaa2_fd_get_offset(fd) is
448 bytes of which XDP have reserved 256 bytes. As frame_sz is
calculated as an offset from xdp_buff.data_hard_start, an adjust from
the full PAGE_SIZE == DPAA2_ETH_RX_BUF_RAW_SIZE.

When doing XDP_REDIRECT, the driver doesn't need this reserved headroom
any-longer and allows xdp_do_redirect() to use it. This is an advantage
for the drivers own ndo-xdp_xmit, as it uses part of this headroom for
itself.  Patch also adjust frame_sz in this case.

The driver cannot support XDP data_meta, because it uses the headroom
just before xdp.data for struct dpaa2_eth_swa (DPAA2_ETH_SWA_SIZE=64),
when transmitting the packet. When transmitting a xdp_frame in
dpaa2_eth_xdp_xmit_frame (call via ndo_xdp_xmit) is uses this area to
store a pointer to xdp_frame and dma_size, which is used in TX
completion (free_tx_fd) to return frame via xdp_return_frame().

Cc: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
---
 drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
index 0f3e842a4fd6..8c8d95aa1dfd 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
@@ -331,6 +331,9 @@ static u32 run_xdp(struct dpaa2_eth_priv *priv,
 	xdp_set_data_meta_invalid(&xdp);
 	xdp.rxq = &ch->xdp_rxq;
 
+	xdp.frame_sz = DPAA2_ETH_RX_BUF_RAW_SIZE -
+		(dpaa2_fd_get_offset(fd) - XDP_PACKET_HEADROOM);
+
 	xdp_act = bpf_prog_run_xdp(xdp_prog, &xdp);
 
 	/* xdp.data pointer may have changed */
@@ -366,7 +369,11 @@ static u32 run_xdp(struct dpaa2_eth_priv *priv,
 		dma_unmap_page(priv->net_dev->dev.parent, addr,
 			       DPAA2_ETH_RX_BUF_SIZE, DMA_BIDIRECTIONAL);
 		ch->buf_count--;
+
+		/* Allow redirect use of full headroom */
 		xdp.data_hard_start = vaddr;
+		xdp.frame_sz = DPAA2_ETH_RX_BUF_RAW_SIZE;
+
 		err = xdp_do_redirect(priv->net_dev, &xdp, xdp_prog);
 		if (unlikely(err))
 			ch->stats.xdp_drop++;