kernel/drivers/net/ethernet/intel/libeth/xsk.c, branch master

libeth, idpf: use truesize as XDP RxQ info frag_size

2026-03-05T16:02:05Z

The only user of frag_size field in XDP RxQ info is bpf_xdp_frags_increase_tail(). It clearly expects whole buffer size instead of DMA write size. Different assumptions in idpf driver configuration lead to negative tailroom. To make it worse, buffer sizes are not actually uniform in idpf when splitq is enabled, as there are several buffer queues, so rxq->rx_buf_size is meaningless in this case. Use truesize of the first bufq in AF_XDP ZC, as there is only one. Disable growing tail for regular splitq. Fixes: ac8a861f632e ("idpf: prepare structures to support XDP") Reviewed-by: Aleksandr Loktionov Signed-off-by: Larysa Zaremba Link: https://patch.msgid.link/20260305111253.2317394-8-larysa.zaremba@intel.com Signed-off-by: Jakub Kicinski

libeth: xsk: add XSkFQ refill and XSk wakeup helpers

2025-06-16T18:40:15Z

XSkFQ refill is pretty generic across the drivers minus FQ descriptor filling and can easily be unified with one inline callback. XSk wakeup is usually not, but here, instead of commonly used "SW interrupts", I picked firing an IPI. In most tests, it showed better performance; it also provides better control for userspace on which CPU will handle the xmit, as SW interrupts honor IRQ affinity no matter which core produces XSk xmit descs (while XDPSQs are associated 1:1 with cores having the same ID). Signed-off-by: Alexander Lobakin Signed-off-by: Tony Nguyen

libeth: xsk: add XSk Rx processing support

2025-06-16T18:40:15Z

Add XSk counterparts for preparing XSk &libeth_xdp_buff (adding head and frags), running the program, and handling the verdict, inc. XDP_PASS. Shortcuts in comparison with regular Rx: frags and all verdicts except XDP_REDIRECT are under unlikely() and out of line; no checks for XDP program presence as it's always true for XSk. Suggested-by: Maciej Fijalkowski # optimizations Signed-off-by: Alexander Lobakin Signed-off-by: Tony Nguyen

libeth: xsk: add XSk xmit functions

2025-06-16T18:40:15Z

Reuse core sending functions to send XSk xmit frames. Both metadata and no metadata pools/driver are supported. libeth_xdp also provides generic XSk metadata ops, currently with the checksum offload only and for cases when HW doesn't require supplying L3/L4 checksum offsets. Drivers are free to pass their own ops. &libeth_xdp_tx_bulk is not used here as it would be redundant; pool->tx_descs are accessed directly. Fake "libeth_xsktmo" is needed to hide implementation details from the drivers when they want to use the generic ops: the original struct is defined in the same file where dev->xsk_tx_metadata_ops gets set to avoid duplication of slowpath; at the same time; XSk xmit functions use local "fast" copy to inline XMO callbacks. Tx descriptor filling loop is unrolled by 8. Suggested-by: Maciej Fijalkowski # optimizations Signed-off-by: Alexander Lobakin Signed-off-by: Tony Nguyen

libeth: xsk: add XSk XDP_TX sending helpers

2025-06-16T18:40:15Z

Add Xsk counterparts for XDP_TX buffer sending and completion. The same base structures and functions used from the libeth_xdp core, with adjustments to that XSk Rx always operates on &xdp_buff_xsk for both head and frags. And unlike regular Rx, here unlikely() are used for frags, as the header split gives no benefits for XSk Rx, at least for now. Signed-off-by: Alexander Lobakin Signed-off-by: Tony Nguyen