1 files changed, 242 insertions, 0 deletions
diff --git a/include/net/libeth/rx.h b/include/net/libeth/rx.h
new file mode 100644
index 000000000000..f29ea3e34c6c
--- /dev/null
+++ b/include/net/libeth/rx.h
@@ -0,0 +1,242 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright (C) 2024 Intel Corporation */
+
+#ifndef __LIBETH_RX_H
+#define __LIBETH_RX_H
+
+#include <linux/if_vlan.h>
+
+#include <net/page_pool/helpers.h>
+#include <net/xdp.h>
+
+/* Rx buffer management */
+
+/* Space reserved in front of each frame */
+#define LIBETH_SKB_HEADROOM	(NET_SKB_PAD + NET_IP_ALIGN)
+/* Maximum headroom for worst-case calculations */
+#define LIBETH_MAX_HEADROOM	LIBETH_SKB_HEADROOM
+/* Link layer / L2 overhead: Ethernet, 2 VLAN tags (C + S), FCS */
+#define LIBETH_RX_LL_LEN	(ETH_HLEN + 2 * VLAN_HLEN + ETH_FCS_LEN)
+
+/* Always use order-0 pages */
+#define LIBETH_RX_PAGE_ORDER	0
+/* Pick a sane buffer stride and align to a cacheline boundary */
+#define LIBETH_RX_BUF_STRIDE	SKB_DATA_ALIGN(128)
+/* HW-writeable space in one buffer: truesize - headroom/tailroom, aligned */
+#define LIBETH_RX_PAGE_LEN(hr)						  \
+	ALIGN_DOWN(SKB_MAX_ORDER(hr, LIBETH_RX_PAGE_ORDER),		  \
+		   LIBETH_RX_BUF_STRIDE)
+
+/**
+ * struct libeth_fqe - structure representing an Rx buffer (fill queue element)
+ * @page: page holding the buffer
+ * @offset: offset from the page start (to the headroom)
+ * @truesize: total space occupied by the buffer (w/ headroom and tailroom)
+ *
+ * Depending on the MTU, API switches between one-page-per-frame and shared
+ * page model (to conserve memory on bigger-page platforms). In case of the
+ * former, @offset is always 0 and @truesize is always ```PAGE_SIZE```.
+ */
+struct libeth_fqe {
+	struct page		*page;
+	u32			offset;
+	u32			truesize;
+} __aligned_largest;
+
+/**
+ * struct libeth_fq - structure representing a buffer (fill) queue
+ * @fp: hotpath part of the structure
+ * @pp: &page_pool for buffer management
+ * @fqes: array of Rx buffers
+ * @truesize: size to allocate per buffer, w/overhead
+ * @count: number of descriptors/buffers the queue has
+ * @buf_len: HW-writeable length per each buffer
+ * @nid: ID of the closest NUMA node with memory
+ */
+struct libeth_fq {
+	struct_group_tagged(libeth_fq_fp, fp,
+		struct page_pool	*pp;
+		struct libeth_fqe	*fqes;
+
+		u32			truesize;
+		u32			count;
+	);
+
+	/* Cold fields */
+	u32			buf_len;
+	int			nid;
+};
+
+int libeth_rx_fq_create(struct libeth_fq *fq, struct napi_struct *napi);
+void libeth_rx_fq_destroy(struct libeth_fq *fq);
+
+/**
+ * libeth_rx_alloc - allocate a new Rx buffer
+ * @fq: fill queue to allocate for
+ * @i: index of the buffer within the queue
+ *
+ * Return: DMA address to be passed to HW for Rx on successful allocation,
+ * ```DMA_MAPPING_ERROR``` otherwise.
+ */
+static inline dma_addr_t libeth_rx_alloc(const struct libeth_fq_fp *fq, u32 i)
+{
+	struct libeth_fqe *buf = &fq->fqes[i];
+
+	buf->truesize = fq->truesize;
+	buf->page = page_pool_dev_alloc(fq->pp, &buf->offset, &buf->truesize);
+	if (unlikely(!buf->page))
+		return DMA_MAPPING_ERROR;
+
+	return page_pool_get_dma_addr(buf->page) + buf->offset +
+	       fq->pp->p.offset;
+}
+
+void libeth_rx_recycle_slow(struct page *page);
+
+/**
+ * libeth_rx_sync_for_cpu - synchronize or recycle buffer post DMA
+ * @fqe: buffer to process
+ * @len: frame length from the descriptor
+ *
+ * Process the buffer after it's written by HW. The regular path is to
+ * synchronize DMA for CPU, but in case of no data it will be immediately
+ * recycled back to its PP.
+ *
+ * Return: true when there's data to process, false otherwise.
+ */
+static inline bool libeth_rx_sync_for_cpu(const struct libeth_fqe *fqe,
+					  u32 len)
+{
+	struct page *page = fqe->page;
+
+	/* Very rare, but possible case. The most common reason:
+	 * the last fragment contained FCS only, which was then
+	 * stripped by the HW.
+	 */
+	if (unlikely(!len)) {
+		libeth_rx_recycle_slow(page);
+		return false;
+	}
+
+	page_pool_dma_sync_for_cpu(page->pp, page, fqe->offset, len);
+
+	return true;
+}
+
+/* Converting abstract packet type numbers into a software structure with
+ * the packet parameters to do O(1) lookup on Rx.
+ */
+
+enum {
+	LIBETH_RX_PT_OUTER_L2			= 0U,
+	LIBETH_RX_PT_OUTER_IPV4,
+	LIBETH_RX_PT_OUTER_IPV6,
+};
+
+enum {
+	LIBETH_RX_PT_NOT_FRAG			= 0U,
+	LIBETH_RX_PT_FRAG,
+};
+
+enum {
+	LIBETH_RX_PT_TUNNEL_IP_NONE		= 0U,
+	LIBETH_RX_PT_TUNNEL_IP_IP,
+	LIBETH_RX_PT_TUNNEL_IP_GRENAT,
+	LIBETH_RX_PT_TUNNEL_IP_GRENAT_MAC,
+	LIBETH_RX_PT_TUNNEL_IP_GRENAT_MAC_VLAN,
+};
+
+enum {
+	LIBETH_RX_PT_TUNNEL_END_NONE		= 0U,
+	LIBETH_RX_PT_TUNNEL_END_IPV4,
+	LIBETH_RX_PT_TUNNEL_END_IPV6,
+};
+
+enum {
+	LIBETH_RX_PT_INNER_NONE			= 0U,
+	LIBETH_RX_PT_INNER_UDP,
+	LIBETH_RX_PT_INNER_TCP,
+	LIBETH_RX_PT_INNER_SCTP,
+	LIBETH_RX_PT_INNER_ICMP,
+	LIBETH_RX_PT_INNER_TIMESYNC,
+};
+
+#define LIBETH_RX_PT_PAYLOAD_NONE		PKT_HASH_TYPE_NONE
+#define LIBETH_RX_PT_PAYLOAD_L2			PKT_HASH_TYPE_L2
+#define LIBETH_RX_PT_PAYLOAD_L3			PKT_HASH_TYPE_L3
+#define LIBETH_RX_PT_PAYLOAD_L4			PKT_HASH_TYPE_L4
+
+struct libeth_rx_pt {
+	u32					outer_ip:2;
+	u32					outer_frag:1;
+	u32					tunnel_type:3;
+	u32					tunnel_end_prot:2;
+	u32					tunnel_end_frag:1;
+	u32					inner_prot:3;
+	enum pkt_hash_types			payload_layer:2;
+
+	u32					pad:2;
+	enum xdp_rss_hash_type			hash_type:16;
+};
+
+void libeth_rx_pt_gen_hash_type(struct libeth_rx_pt *pt);
+
+/**
+ * libeth_rx_pt_get_ip_ver - get IP version from a packet type structure
+ * @pt: packet type params
+ *
+ * Wrapper to compile out the IPv6 code from the drivers when not supported
+ * by the kernel.
+ *
+ * Return: @pt.outer_ip or stub for IPv6 when not compiled-in.
+ */
+static inline u32 libeth_rx_pt_get_ip_ver(struct libeth_rx_pt pt)
+{
+#if !IS_ENABLED(CONFIG_IPV6)
+	switch (pt.outer_ip) {
+	case LIBETH_RX_PT_OUTER_IPV4:
+		return LIBETH_RX_PT_OUTER_IPV4;
+	default:
+		return LIBETH_RX_PT_OUTER_L2;
+	}
+#else
+	return pt.outer_ip;
+#endif
+}
+
+/* libeth_has_*() can be used to quickly check whether the HW metadata is
+ * available to avoid further expensive processing such as descriptor reads.
+ * They already check for the corresponding netdev feature to be enabled,
+ * thus can be used as drop-in replacements.
+ */
+
+static inline bool libeth_rx_pt_has_checksum(const struct net_device *dev,
+					     struct libeth_rx_pt pt)
+{
+	/* Non-zero _INNER* is only possible when _OUTER_IPV* is set,
+	 * it is enough to check only for the L4 type.
+	 */
+	return likely(pt.inner_prot > LIBETH_RX_PT_INNER_NONE &&
+		      (dev->features & NETIF_F_RXCSUM));
+}
+
+static inline bool libeth_rx_pt_has_hash(const struct net_device *dev,
+					 struct libeth_rx_pt pt)
+{
+	return likely(pt.payload_layer > LIBETH_RX_PT_PAYLOAD_NONE &&
+		      (dev->features & NETIF_F_RXHASH));
+}
+
+/**
+ * libeth_rx_pt_set_hash - fill in skb hash value basing on the PT
+ * @skb: skb to fill the hash in
+ * @hash: 32-bit hash value from the descriptor
+ * @pt: packet type
+ */
+static inline void libeth_rx_pt_set_hash(struct sk_buff *skb, u32 hash,
+					 struct libeth_rx_pt pt)
+{
+	skb_set_hash(skb, hash, pt.payload_layer);
+}
+
+#endif /* __LIBETH_RX_H */