[PATCH iwl-next v5 2/5] libeth: handle creating pools with unreadable buffers
From: Alexander Lobakin <aleksander.lobakin@intel.com>
Date: 2026-05-05 15:30:43
Also in:
intel-wired-lan, lkml
Subsystem:
intel ethernet drivers, libeth common ethernet library, networking drivers, networking [general], the rest · Maintainers:
Tony Nguyen, Przemek Kitszel, Alexander Lobakin, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
libeth uses netmems for quite some time already, so in order to support unreadable frags / memory providers, it only needs to set PP_FLAG_ALLOW_UNREADABLE_NETMEM when needed. Also add a couple sanity checks to make sure the driver didn't mess up the configuration options and, in case when an MP is installed, return the truesize always equal to PAGE_SIZE, so that libeth_rx_alloc() will never try to allocate frags. Memory providers manage buffers on their own and expect 1:1 buffer / HW Rx descriptor association. Bonus: mention in the libeth_sqe_type description that LIBETH_SQE_EMPTY should also be used for netmem Tx SQEs -- they don't need DMA unmapping. Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Reviewed-by: Aleksandr Loktionov <redacted> Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com> --- include/net/libeth/tx.h | 2 +- drivers/net/ethernet/intel/libeth/rx.c | 42 ++++++++++++++++++++++++++ 2 files changed, 43 insertions(+), 1 deletion(-)
diff --git a/include/net/libeth/tx.h b/include/net/libeth/tx.h
index c3db5c6f1641..a66fc2b3a114 100644
--- a/include/net/libeth/tx.h
+++ b/include/net/libeth/tx.h@@ -12,7 +12,7 @@ /** * enum libeth_sqe_type - type of &libeth_sqe to act on Tx completion - * @LIBETH_SQE_EMPTY: unused/empty OR XDP_TX/XSk frame, no action required + * @LIBETH_SQE_EMPTY: empty OR netmem/XDP_TX/XSk frame, no action required * @LIBETH_SQE_CTX: context descriptor with empty SQE, no action required * @LIBETH_SQE_SLAB: kmalloc-allocated buffer, unmap and kfree() * @LIBETH_SQE_FRAG: mapped skb frag, only unmap DMA
diff --git a/drivers/net/ethernet/intel/libeth/rx.c b/drivers/net/ethernet/intel/libeth/rx.c
index 8874b714cdcc..11e6e8f353ef 100644
--- a/drivers/net/ethernet/intel/libeth/rx.c
+++ b/drivers/net/ethernet/intel/libeth/rx.c@@ -6,6 +6,7 @@ #include <linux/export.h> #include <net/libeth/rx.h> +#include <net/netdev_queues.h> /* Rx buffer management */
@@ -139,9 +140,47 @@ static bool libeth_rx_page_pool_params_zc(struct libeth_fq *fq, fq->buf_len = clamp(mtu, LIBETH_RX_BUF_STRIDE, max); fq->truesize = fq->buf_len; + /* + * Allow frags only for kernel pages. `fq->truesize == pp->max_len` + * will always fall back to regular page_pool_alloc_netmems() + * regardless of the MTU / FQ buffer size. + */ + if (pp->flags & PP_FLAG_ALLOW_UNREADABLE_NETMEM) + fq->truesize = pp->max_len; + return true; } +/** + * libeth_rx_page_pool_check_unread - check input params for unreadable MPs + * @fq: buffer queue to check + * @pp: &page_pool_params for the queue + * + * Make sure we don't create an invalid pool with full-frame unreadable + * buffers, bidirectional unreadable buffers or so, and configure the + * ZC payload pool accordingly. + * + * Return: true on success, false on invalid input params. + */ +static bool libeth_rx_page_pool_check_unread(const struct libeth_fq *fq, + struct page_pool_params *pp) +{ + if (!netif_rxq_has_unreadable_mp(pp->netdev, pp->queue_idx)) + return true; + + /* For now, the core stack doesn't allow XDP with unreadable frags */ + if (fq->xdp) + return false; + + /* It should be either a header pool or a ZC payload pool */ + if (fq->type == LIBETH_FQE_HDR) + return !fq->hsplit; + + pp->flags |= PP_FLAG_ALLOW_UNREADABLE_NETMEM; + + return fq->hsplit; +} + /** * libeth_rx_fq_create - create a PP with the default libeth settings * @fq: buffer queue struct to fill
@@ -165,6 +204,9 @@ int libeth_rx_fq_create(struct libeth_fq *fq, struct napi_struct *napi) struct page_pool *pool; int ret; + if (!libeth_rx_page_pool_check_unread(fq, &pp)) + return -EINVAL; + pp.dma_dir = fq->xdp ? DMA_BIDIRECTIONAL : DMA_FROM_DEVICE; if (!fq->hsplit)
--
2.54.0