1/* SPDX-License-Identifier: GPL-2.0-only */
  2/* include/net/xdp.h
  3 *
  4 * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
  5 */
  6#ifndef __LINUX_NET_XDP_H__
  7#define __LINUX_NET_XDP_H__
  8
  9/**
 10 * DOC: XDP RX-queue information
 11 *
 12 * The XDP RX-queue info (xdp_rxq_info) is associated with the driver
 13 * level RX-ring queues.  It is information that is specific to how
 14 * the driver have configured a given RX-ring queue.
 15 *
 16 * Each xdp_buff frame received in the driver carry a (pointer)
 17 * reference to this xdp_rxq_info structure.  This provides the XDP
 18 * data-path read-access to RX-info for both kernel and bpf-side
 19 * (limited subset).
 20 *
 21 * For now, direct access is only safe while running in NAPI/softirq
 22 * context.  Contents is read-mostly and must not be updated during
 23 * driver NAPI/softirq poll.
 24 *
 25 * The driver usage API is a register and unregister API.
 26 *
 27 * The struct is not directly tied to the XDP prog.  A new XDP prog
 28 * can be attached as long as it doesn't change the underlying
 29 * RX-ring.  If the RX-ring does change significantly, the NIC driver
 30 * naturally need to stop the RX-ring before purging and reallocating
 31 * memory.  In that process the driver MUST call unregistor (which
 32 * also apply for driver shutdown and unload).  The register API is
 33 * also mandatory during RX-ring setup.
 34 */
 35
 36enum xdp_mem_type {
 37	MEM_TYPE_PAGE_SHARED = 0, /* Split-page refcnt based model */
 38	MEM_TYPE_PAGE_ORDER0,     /* Orig XDP full page model */
 39	MEM_TYPE_PAGE_POOL,
 40	MEM_TYPE_ZERO_COPY,
 41	MEM_TYPE_MAX,
 42};
 43
 44/* XDP flags for ndo_xdp_xmit */
 45#define XDP_XMIT_FLUSH		(1U << 0)	/* doorbell signal consumer */
 46#define XDP_XMIT_FLAGS_MASK	XDP_XMIT_FLUSH
 47
 48struct xdp_mem_info {
 49	u32 type; /* enum xdp_mem_type, but known size type */
 50	u32 id;
 51};
 52
 53struct page_pool;
 54
 55struct zero_copy_allocator {
 56	void (*free)(struct zero_copy_allocator *zca, unsigned long handle);
 57};
 58
 59struct xdp_rxq_info {
 60	struct net_device *dev;
 61	u32 queue_index;
 62	u32 reg_state;
 63	struct xdp_mem_info mem;
 64} ____cacheline_aligned; /* perf critical, avoid false-sharing */
 65
 66struct xdp_buff {
 67	void *data;
 68	void *data_end;
 69	void *data_meta;
 70	void *data_hard_start;
 71	unsigned long handle;
 72	struct xdp_rxq_info *rxq;
 73};
 74
 75struct xdp_frame {
 76	void *data;
 77	u16 len;
 78	u16 headroom;
 79	u16 metasize;
 80	/* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time,
 81	 * while mem info is valid on remote CPU.
 82	 */
 83	struct xdp_mem_info mem;
 84	struct net_device *dev_rx; /* used by cpumap */
 85};
 86
 87/* Clear kernel pointers in xdp_frame */
 88static inline void xdp_scrub_frame(struct xdp_frame *frame)
 89{
 90	frame->data = NULL;
 91	frame->dev_rx = NULL;
 92}
 93
 94struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);
 95
 96/* Convert xdp_buff to xdp_frame */
 97static inline
 98struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp)
 99{
100	struct xdp_frame *xdp_frame;
101	int metasize;
102	int headroom;
103
104	if (xdp->rxq->mem.type == MEM_TYPE_ZERO_COPY)
105		return xdp_convert_zc_to_xdp_frame(xdp);
106
107	/* Assure headroom is available for storing info */
108	headroom = xdp->data - xdp->data_hard_start;
109	metasize = xdp->data - xdp->data_meta;
110	metasize = metasize > 0 ? metasize : 0;
111	if (unlikely((headroom - metasize) < sizeof(*xdp_frame)))
112		return NULL;
113
114	/* Store info in top of packet */
115	xdp_frame = xdp->data_hard_start;
116
117	xdp_frame->data = xdp->data;
118	xdp_frame->len  = xdp->data_end - xdp->data;
119	xdp_frame->headroom = headroom - sizeof(*xdp_frame);
120	xdp_frame->metasize = metasize;
121
122	/* rxq only valid until napi_schedule ends, convert to xdp_mem_info */
123	xdp_frame->mem = xdp->rxq->mem;
124
125	return xdp_frame;
126}
127
128void xdp_return_frame(struct xdp_frame *xdpf);
129void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);
130void xdp_return_buff(struct xdp_buff *xdp);
131
132/* When sending xdp_frame into the network stack, then there is no
133 * return point callback, which is needed to release e.g. DMA-mapping
134 * resources with page_pool.  Thus, have explicit function to release
135 * frame resources.
136 */
137void __xdp_release_frame(void *data, struct xdp_mem_info *mem);
138static inline void xdp_release_frame(struct xdp_frame *xdpf)
139{
140	struct xdp_mem_info *mem = &xdpf->mem;
141
142	/* Curr only page_pool needs this */
143	if (mem->type == MEM_TYPE_PAGE_POOL)
144		__xdp_release_frame(xdpf->data, mem);
145}
146
147int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
148		     struct net_device *dev, u32 queue_index);
149void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq);
150void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq);
151bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq);
152int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
153			       enum xdp_mem_type type, void *allocator);
154void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq);
155
156/* Drivers not supporting XDP metadata can use this helper, which
157 * rejects any room expansion for metadata as a result.
158 */
159static __always_inline void
160xdp_set_data_meta_invalid(struct xdp_buff *xdp)
161{
162	xdp->data_meta = xdp->data + 1;
163}
164
165static __always_inline bool
166xdp_data_meta_unsupported(const struct xdp_buff *xdp)
167{
168	return unlikely(xdp->data_meta > xdp->data);
169}
170
171struct xdp_attachment_info {
172	struct bpf_prog *prog;
173	u32 flags;
174};
175
176struct netdev_bpf;
177int xdp_attachment_query(struct xdp_attachment_info *info,
178			 struct netdev_bpf *bpf);
179bool xdp_attachment_flags_ok(struct xdp_attachment_info *info,
180			     struct netdev_bpf *bpf);
181void xdp_attachment_setup(struct xdp_attachment_info *info,
182			  struct netdev_bpf *bpf);
183
184#endif /* __LINUX_NET_XDP_H__ */