From cb6cc8ed77177c7553c2f8ac8605d32de58f43ac Mon Sep 17 00:00:00 2001 From: Furong Xu <0x1207@gmail.com> Date: Fri, 7 Feb 2025 16:56:39 +0800 Subject: [PATCH] net: stmmac: Apply new page pool parameters when SPH is enabled Commit df542f669307 ("net: stmmac: Switch to zero-copy in non-XDP RX path") makes DMA write received frame into buffer at offset of NET_SKB_PAD and sets page pool parameters to sync from offset of NET_SKB_PAD. But when Header Payload Split is enabled, the header is written at offset of NET_SKB_PAD, while the payload is written at offset of zero. Uncorrect offset parameter for the payload breaks dma coherence [1] since both CPU and DMA touch the page buffer from offset of zero which is not handled by the page pool sync parameter. And in case the DMA cannot split the received frame, for example, a large L2 frame, pp_params.max_len should grow to match the tail of entire frame. [1] https://lore.kernel.org/netdev/d465f277-bac7-439f-be1d-9a47dfe2d951@nvidia.com/ Reported-by: Jon Hunter Reported-by: Brad Griffis Suggested-by: Ido Schimmel Fixes: df542f669307 ("net: stmmac: Switch to zero-copy in non-XDP RX path") Signed-off-by: Furong Xu <0x1207@gmail.com> Tested-by: Jon Hunter Tested-by: Thierry Reding Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20250207085639.13580-1-0x1207@gmail.com Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index b34ebb916b89..c0ae7db96f46 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -2094,6 +2094,11 @@ static int __alloc_dma_rx_desc_resources(struct stmmac_priv *priv, pp_params.offset = stmmac_rx_offset(priv); pp_params.max_len = dma_conf->dma_buf_sz; + if (priv->sph) { + pp_params.offset = 0; + pp_params.max_len += stmmac_rx_offset(priv); + } + rx_q->page_pool = page_pool_create(&pp_params); if (IS_ERR(rx_q->page_pool)) { ret = PTR_ERR(rx_q->page_pool);