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/* SPDX-License-Identifier: GPL-2.0-only */
/* include/net/xdp.h
* Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
#ifndef __LINUX_NET_XDP_H__
#define __LINUX_NET_XDP_H__
* DOC: XDP RX-queue information
* The XDP RX-queue info (xdp_rxq_info) is associated with the driver
* level RX-ring queues. It is information that is specific to how
* the driver have configured a given RX-ring queue.
* Each xdp_buff frame received in the driver carry a (pointer)
* reference to this xdp_rxq_info structure. This provides the XDP
* data-path read-access to RX-info for both kernel and bpf-side
* (limited subset).
* For now, direct access is only safe while running in NAPI/softirq
* context. Contents is read-mostly and must not be updated during
* driver NAPI/softirq poll.
* The driver usage API is a register and unregister API.
* The struct is not directly tied to the XDP prog. A new XDP prog
* can be attached as long as it doesn't change the underlying
* RX-ring. If the RX-ring does change significantly, the NIC driver
* naturally need to stop the RX-ring before purging and reallocating
* memory. In that process the driver MUST call unregistor (which
* also apply for driver shutdown and unload). The register API is
* also mandatory during RX-ring setup.
enum xdp_mem_type {
MEM_TYPE_PAGE_SHARED = 0, /* Split-page refcnt based model */
MEM_TYPE_PAGE_ORDER0, /* Orig XDP full page model */
/* XDP flags for ndo_xdp_xmit */
#define XDP_XMIT_FLUSH (1U << 0) /* doorbell signal consumer */
struct xdp_mem_info {
u32 type; /* enum xdp_mem_type, but known size type */
u32 id;
struct page_pool;
struct zero_copy_allocator {
void (*free)(struct zero_copy_allocator *zca, unsigned long handle);
struct xdp_rxq_info {
struct net_device *dev;
u32 queue_index;
u32 reg_state;
struct xdp_mem_info mem;
} ____cacheline_aligned; /* perf critical, avoid false-sharing */
struct xdp_buff {
void *data;
void *data_end;
void *data_meta;
void *data_hard_start;
unsigned long handle;
struct xdp_rxq_info *rxq;
struct xdp_frame {
void *data;
u16 len;
u16 headroom;
u16 metasize;
/* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time,
* while mem info is valid on remote CPU.
struct xdp_mem_info mem;
struct net_device *dev_rx; /* used by cpumap */
/* Clear kernel pointers in xdp_frame */
static inline void xdp_scrub_frame(struct xdp_frame *frame)
frame->data = NULL;
frame->dev_rx = NULL;
struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);
/* Convert xdp_buff to xdp_frame */
static inline
struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp)
struct xdp_frame *xdp_frame;
int metasize;
int headroom;
if (xdp->rxq->mem.type == MEM_TYPE_ZERO_COPY)
return xdp_convert_zc_to_xdp_frame(xdp);
/* Assure headroom is available for storing info */
headroom = xdp->data - xdp->data_hard_start;
metasize = xdp->data - xdp->data_meta;
metasize = metasize > 0 ? metasize : 0;
if (unlikely((headroom - metasize) < sizeof(*xdp_frame)))
return NULL;
/* Store info in top of packet */
xdp_frame = xdp->data_hard_start;
xdp_frame->data = xdp->data;
xdp_frame->len = xdp->data_end - xdp->data;
xdp_frame->headroom = headroom - sizeof(*xdp_frame);
xdp_frame->metasize = metasize;
/* rxq only valid until napi_schedule ends, convert to xdp_mem_info */
xdp_frame->mem = xdp->rxq->mem;
return xdp_frame;
void xdp_return_frame(struct xdp_frame *xdpf);
void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);
void xdp_return_buff(struct xdp_buff *xdp);
/* When sending xdp_frame into the network stack, then there is no
* return point callback, which is needed to release e.g. DMA-mapping
* resources with page_pool. Thus, have explicit function to release
* frame resources.
void __xdp_release_frame(void *data, struct xdp_mem_info *mem);
static inline void xdp_release_frame(struct xdp_frame *xdpf)
struct xdp_mem_info *mem = &xdpf->mem;
/* Curr only page_pool needs this */
if (mem->type == MEM_TYPE_PAGE_POOL)
__xdp_release_frame(xdpf->data, mem);
int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
struct net_device *dev, u32 queue_index);
void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq);
void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq);
bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq);
int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
enum xdp_mem_type type, void *allocator);
void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq);
/* Drivers not supporting XDP metadata can use this helper, which
* rejects any room expansion for metadata as a result.
static __always_inline void
xdp_set_data_meta_invalid(struct xdp_buff *xdp)
xdp->data_meta = xdp->data + 1;
static __always_inline bool
xdp_data_meta_unsupported(const struct xdp_buff *xdp)
return unlikely(xdp->data_meta > xdp->data);
struct xdp_attachment_info {
struct bpf_prog *prog;
u32 flags;
struct netdev_bpf;
int xdp_attachment_query(struct xdp_attachment_info *info,
struct netdev_bpf *bpf);
bool xdp_attachment_flags_ok(struct xdp_attachment_info *info,
struct netdev_bpf *bpf);
void xdp_attachment_setup(struct xdp_attachment_info *info,
struct netdev_bpf *bpf);
#endif /* __LINUX_NET_XDP_H__ */