[PATCH net-next v3 0/6] net: bcmgenet: add XDP support

Nicolai Buchwitz
2026-03-19T11:54:51Z

Add XDP support to the bcmgenet driver, covering XDP_PASS, XDP_DROP,
XDP_TX, XDP_REDIRECT, and ndo_xdp_xmit.

The first patch converts the RX path from the existing kmalloc-based
allocation to page_pool, which is a prerequisite for XDP. The remaining
patches incrementally add XDP functionality and per-action statistics.

Tested on Raspberry Pi CM4 (BCM2711, bcmgenet, 1Gbps link):
- XDP_PASS: 943 Mbit/s TX, 935 Mbit/s RX (no regression vs baseline)
- XDP_PASS latency: 0.164ms avg, 0% packet loss
- XDP_DROP: all inbound traffic blocked as expected
- XDP_TX: TX counter increments (packet reflection working)
- Link flap with XDP attached: no errors
- Program swap under iperf3 load: no errors
- Upstream XDP selftests (xdp.py): pass_sb, drop_sb, tx_sb passing

Changes since v2:
- Fixed xdp_prepare_buff() called with meta_valid=false, causing
bcmgenet_xdp_build_skb() to compute metasize=UINT_MAX and corrupt
skb meta_len. Now passes true. (Simon Horman)
- Removed bcmgenet_dump_tx_queue() for ring 16 in bcmgenet_timeout().
Ring 16 has no netdev TX queue, so netdev_get_tx_queue(dev, 16)
accessed beyond the allocated _tx array. (Simon Horman)
- Fixed checkpatch alignment warnings in patches 4 and 5.

Changes since v1:
- Fixed tx_rings[DESC_INDEX] out-of-bounds access. Expanded array
to DESC_INDEX+1 and initialized ring 16 with dedicated BDs.
- Use ring 16 (hardware default descriptor ring) for XDP TX,
isolating from normal SKB TX queues.
- Piggyback ring 16 TX completion on RX NAPI poll (INTRL2_1 bit
collision with RX ring 0).
- Fixed ring 16 TX reclaim: skip INTRL2_1 clear, skip BQL
completion, use non-destructive reclaim in RX poll path.
- Prepend zeroed TSB before XDP TX frame data (TBUF_64B_EN requires
64-byte struct status_64 prefix on all TX buffers).
- Tested with upstream XDP selftests (xdp.py): pass_sb, drop_sb,
tx_sb all passing. The multi-buffer tests (pass_mb, drop_mb,
tx_mb) fail because bcmgenet does not support jumbo frames /
MTU changes; I plan to add ndo_change_mtu support in a follow-up
series.

Nicolai Buchwitz (6):
net: bcmgenet: convert RX path to page_pool
net: bcmgenet: register xdp_rxq_info for each RX ring
net: bcmgenet: add basic XDP support (PASS/DROP)
net: bcmgenet: add XDP_TX support
net: bcmgenet: add XDP_REDIRECT and ndo_xdp_xmit support
net: bcmgenet: add XDP statistics counters

drivers/net/ethernet/broadcom/Kconfig | 1 +
.../net/ethernet/broadcom/genet/bcmgenet.c | 608 +++++++++++++++---
.../net/ethernet/broadcom/genet/bcmgenet.h | 20 +-
3 files changed, 537 insertions(+), 92 deletions(-)

--
2.51.0