[PATCH bpf-next V2 2/5] igc: add igc_xdp_buff wrapper for xdp_buff in driver

Jesper Dangaard Brouer
2023-04-18T13:31:51Z

Driver specific metadata data for XDP-hints kfuncs are propagated via tail
extending the struct xdp_buff with a locally scoped driver struct.

Zero-Copy AF_XDP/XSK does similar tricks via struct xdp_buff_xsk. This
xdp_buff_xsk struct contains a CB area (24 bytes) that can be used for
extending the locally scoped driver into. The XSK_CHECK_PRIV_TYPE define
catch size violations build time.

The changes needed for AF_XDP zero-copy in igc_clean_rx_irq_zc()
is done in next patch, because the member rx_desc isn't available
at this point.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
---
drivers/net/ethernet/intel/igc/igc.h | 5 +++++
drivers/net/ethernet/intel/igc/igc_main.c | 16 +++++++++-------
2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
index f7f9e217e7b4..76a5115aefc8 100644
--- a/drivers/net/ethernet/intel/igc/igc.h
+++ b/drivers/net/ethernet/intel/igc/igc.h
@@ -499,6 +499,11 @@ struct igc_rx_buffer {
};
};

+/* context wrapper around xdp_buff to provide access to descriptor metadata */
+struct igc_xdp_buff {
+ struct xdp_buff xdp;
+};
+
struct igc_q_vector {
struct igc_adapter *adapter; /* backlink */
void __iomem *itr_register;
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index bfa9768d447f..6a4c7cd706bd 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -2236,6 +2236,8 @@ static bool igc_alloc_rx_buffers_zc(struct igc_ring *ring, u16 count)
if (!count)
return ok;

+ XSK_CHECK_PRIV_TYPE(struct igc_xdp_buff);
+
desc = IGC_RX_DESC(ring, i);
bi = &ring->rx_buffer_info[i];
i -= ring->count;
@@ -2520,8 +2522,8 @@ static int igc_clean_rx_irq(struct igc_q_vector *q_vector, const int budget)
union igc_adv_rx_desc *rx_desc;
struct igc_rx_buffer *rx_buffer;
unsigned int size, truesize;
+ struct igc_xdp_buff ctx;
ktime_t timestamp = 0;
- struct xdp_buff xdp;
int pkt_offset = 0;
void *pktbuf;

@@ -2555,13 +2557,13 @@ static int igc_clean_rx_irq(struct igc_q_vector *q_vector, const int budget)
}

if (!skb) {
- xdp_init_buff(&xdp, truesize, &rx_ring->xdp_rxq);
- xdp_prepare_buff(&xdp, pktbuf - igc_rx_offset(rx_ring),
+ xdp_init_buff(&ctx.xdp, truesize, &rx_ring->xdp_rxq);
+ xdp_prepare_buff(&ctx.xdp, pktbuf - igc_rx_offset(rx_ring),
igc_rx_offset(rx_ring) + pkt_offset,
size, true);
- xdp_buff_clear_frags_flag(&xdp);
+ xdp_buff_clear_frags_flag(&ctx.xdp);

- skb = igc_xdp_run_prog(adapter, &xdp);
+ skb = igc_xdp_run_prog(adapter, &ctx.xdp);
}

if (IS_ERR(skb)) {
@@ -2583,9 +2585,9 @@ static int igc_clean_rx_irq(struct igc_q_vector *q_vector, const int budget)
} else if (skb)
igc_add_rx_frag(rx_ring, rx_buffer, skb, size);
else if (ring_uses_build_skb(rx_ring))
- skb = igc_build_skb(rx_ring, rx_buffer, &xdp);
+ skb = igc_build_skb(rx_ring, rx_buffer, &ctx.xdp);
else
- skb = igc_construct_skb(rx_ring, rx_buffer, &xdp,
+ skb = igc_construct_skb(rx_ring, rx_buffer, &ctx.xdp,
timestamp);

/* exit if we failed to retrieve a buffer */