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b=2WVh2hbq2lGmUG9cb5l4lcUMu80cmP1jiP9qbSY69Ymew/LcpUQhreTptnIz6ZhuB6 7iXz+uaF95kG1CG4tR7+WbgMtb2490+VvYjKD+KbQebepp6/0rD4Xac5c1d8LUKLT5h+ AcO0uQXW6R4Ego1w9AgzdV13HKtRHNjn62L1+eSsBonz/Gl3Dx8b6M7bCABlcGEHnzTY 3Z88OWXiRmURR/6pRYLfgEl0QGtLA/cbS7xPnnLZpU8Uc4hG2ikEiY+54clB5vKAH80Q a8BjfPGtfJ6Z1LDS+m4w8gtPT2o9NqAs2UZi3PTGM2uMwMsICE4XRsfmbK8IoyJ8aL5e 4F+A== X-Forwarded-Encrypted: i=1; AKwUvBy91ZKMSEyfIfDIpr+F34QrxKt0trd7qHq3PREL8MXYR4xa8gpE7frWC3/AAQlJsnE47edDfQ6ahg==@kvack.org X-Gm-Message-State: AFq9FYLzL+updJNMV4Jv1wKKaQHkn+Zi9vmhIfrkzf9z5p16kxz3JDps Qe5AphC1W9jxjgfYBK3Nzw0JQrDSLRXrY67NaOd1gbwZYXQToG4Wtp/uYgHieNpSeAra4ASbtgn tnJLyTg== X-Received: from edev16-n1.prod.google.com ([2002:a05:6402:a2d0:10b0:6aa:e8d7:1a1]) (user=lrizzo job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6402:4605:b0:6ac:7868:b68a with SMTP id 4fb4d7f45d1cf-6afad8ce0efmr2325349a12.9.1791062594530; Sat, 03 Oct 2026 14:23:14 -0700 (PDT) Date: Sat, 3 Oct 2026 21:22:40 +0000 In-Reply-To: <20261003212241.3432303-1-lrizzo@google.com> Mime-Version: 1.0 References: <20261003212241.3432303-1-lrizzo@google.com> X-Mailer: git-send-email 2.56.0.rc1.315.gc6ed9934b7-goog Message-ID: <20261003212241.3432303-22-lrizzo@google.com> Subject: [RFC: DMA_PMD 21/22] net/bnxt: Use DMA_PMD memory for tx header bounce buffers From: Luigi Rizzo To: Luigi Rizzo , Joerg Roedel , Will Deacon , Robin Murphy , Christoph Hellwig , Marek Szyprowski , Andrew Morton , Vlastimil Babka , David Hildenbrand , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Greg Kroah-Hartman , "Rafael J . Wysocki" , Danilo Krummrich , Jonathan Corbet , Jesper Dangaard Brouer , Ilias Apalodimas , Willem de Bruijn , Kuniyuki Iwashima , Joshua Washington , Harshitha Ramamurthy , Saeed Mahameed , Tariq Toukan , Tony Nguyen , Przemek Kitszel , Alexander Lobakin , Michael Chan , Pavan Chebbi , iommu@lists.linux.dev, netdev@vger.kernel.org, linux-mm@kvack.org, driver-core@lists.linux.dev, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Luigi Rizzo Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 1B20E4000C X-Stat-Signature: 37uskseg9yowu7tw9ogti4cyy8fqt76j X-HE-Tag: 1791062595-658107 X-HE-Meta: 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 BM5V0efQ 1AmdjyZHtz89RJ0lMWRDbqeYEox6XCj+pT59zSFMYxV9CfTIF69Q0AVor2cWde2bK6717HD12vk7+PMvt23LF/KtzSPblwYVL4Y7aROJSKI0J60gKBe70TM+rfuzDnojPjHBpeS/TdlftfPW/rPaT9qx7F/GmQxAyztWI08Q8dK7MrjkaaZ5K7J82GVk0n9IKJ+kUIM6e8rqyHrn2xklq+b3yxVwIAypDrpoxknKJFkPG6nkQ1KCixwHzqiZ6lfwgwhM+DSFp1cUBl2YO+wE7EJTqopK0z6Yxj5tzRkTGFfhySkfTY8LtF9KrNiQlf1J6cjvX3fzCRGvZYUjh4Eo9WYz0NX5k7hBISHjpZWrmYuC0TEa8dcgV8B17+k7gKsA0Nd2qgAFlPelTlI8Ax56EX/IMHCBJ5md2W7beWmzMUOyTDlp2wPygyxqGGCo08UognpzAm0ippVM7YWy1P2vBvj8YNnU/WTC3iSs41yKs/DhCKezXoYspIgWnCptRtSQfhppG40baxH4mYeqyM+qbnr+Erb4cRnO0f7geYpcyejOTBM2G/oAz3qJpSe2bm2NO898PLt+R3i8sniwS/3o7pfZzmnaZr2fuViuEyX50trQ6vYpJ8eXHjEQndcL+6ipRPHi5GazR12Wd8hUq7twx9RkIYsgEHbxWjyA7sjjwF6kLzec= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: When dev->dma_pmd_tx_hdrs is enabled, allocate a MAX_TCP_HEADER bounce buffer per TX ring slot out of the DMA_PMD arena. When the linear portion of a transmitted packet is at most MAX_TCP_HEADER bytes, copy it into the pre-mapped bounce buffer instead of calling dma_map_single()/dma_unmap_single() on every packet. Signed-off-by: Luigi Rizzo --- drivers/net/ethernet/broadcom/bnxt/bnxt.c | 45 ++++++++++++++++++----- drivers/net/ethernet/broadcom/bnxt/bnxt.h | 2 + 2 files changed, 37 insertions(+), 10 deletions(-) diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c index d7728d0c5b6e6..b9c91eb3aaddd 100644 --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c @@ -680,13 +680,22 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) length = BNXT_MIN_PKT_SIZE; } - mapping = dma_map_single(&pdev->dev, skb->data, len, DMA_TO_DEVICE); - - if (unlikely(dma_mapping_error(&pdev->dev, mapping))) - goto tx_free; - - dma_unmap_addr_set(tx_buf, mapping, mapping); - dma_unmap_len_set(tx_buf, len, len); + if (txr->tx_hdr_bufs && len + pad <= MAX_TCP_HEADER) { + u32 off = RING_TX(bp, prod) * MAX_TCP_HEADER; + + memcpy(txr->tx_hdr_bufs + off, skb->data, len); + if (pad && !last_frag) + memset(txr->tx_hdr_bufs + off + len, 0, pad); + mapping = txr->tx_hdr_bufs_dma + off; + dma_unmap_len_set(tx_buf, len, 0); + } else { + mapping = dma_map_single(&pdev->dev, skb->data, len, + DMA_TO_DEVICE); + if (unlikely(dma_mapping_error(&pdev->dev, mapping))) + goto tx_free; + dma_unmap_addr_set(tx_buf, mapping, mapping); + dma_unmap_len_set(tx_buf, len, len); + } flags = (len << TX_BD_LEN_SHIFT) | TX_BD_TYPE_LONG_TX_BD | TX_BD_CNT(last_frag + 2); @@ -800,8 +809,9 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) /* start back at beginning and unmap skb */ prod = txr->tx_prod; tx_buf = &txr->tx_buf_ring[RING_TX(bp, prod)]; - dma_unmap_single(&pdev->dev, dma_unmap_addr(tx_buf, mapping), - skb_headlen(skb), DMA_TO_DEVICE); + if (dma_unmap_len(tx_buf, len)) + dma_unmap_single(&pdev->dev, dma_unmap_addr(tx_buf, mapping), + skb_headlen(skb), DMA_TO_DEVICE); prod = NEXT_TX(prod); /* unmap remaining mapped pages */ @@ -885,7 +895,6 @@ static bool __bnxt_tx_int(struct bnxt *bp, struct bnxt_tx_ring_info *txr, dma_unmap_single(&pdev->dev, dma_addr, dma_len, DMA_TO_DEVICE); } - last = tx_buf->nr_frags; for (j = 0; j < last; j++) { @@ -4111,6 +4120,15 @@ static void bnxt_free_tx_rings(struct bnxt *bp) ring = &txr->tx_ring_struct; + if (txr->tx_hdr_bufs) { + dma_free_coherent(&pdev->dev, + ring->ring_mem.nr_pages * + TX_DESC_CNT * MAX_TCP_HEADER, + txr->tx_hdr_bufs, + txr->tx_hdr_bufs_dma); + txr->tx_hdr_bufs = NULL; + } + bnxt_free_ring(bp, &ring->ring_mem); } } @@ -4181,6 +4199,13 @@ static int bnxt_alloc_tx_rings(struct bnxt *bp) if (rc) return rc; } + if (pdev->dev.dma_pmd_tx_hdrs && i >= bp->tx_nr_rings_xdp) + txr->tx_hdr_bufs = + dma_alloc_coherent(&pdev->dev, + ring->ring_mem.nr_pages * + TX_DESC_CNT * MAX_TCP_HEADER, + &txr->tx_hdr_bufs_dma, + GFP_KERNEL | __GFP_NOWARN); qidx = bp->tc_to_qidx[j]; ring->queue_id = bp->q_info[qidx].queue_id; spin_lock_init(&txr->xdp_tx_lock); diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h index c673b2ce4a0d2..b42bbabc0eb98 100644 --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h @@ -1003,6 +1003,8 @@ struct bnxt_tx_ring_info { struct tx_push_buffer *tx_push; dma_addr_t tx_push_mapping; __le64 data_mapping; + void *tx_hdr_bufs; + dma_addr_t tx_hdr_bufs_dma; void *tx_inline_buf; dma_addr_t tx_inline_dma; -- 2.56.0.rc1.315.gc6ed9934b7-goog