dpaa2-eth: Add XDP frame size

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().

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Link: https://lore.kernel.org/bpf/158945339348.97035.8562488847066908856.stgit@firesoul

diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
index 0f3e842..8c8d95a 100644 (file)
--- 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++;