include/net/xdp.h

   1 /* include/net/xdp.h
   2  *
   3  * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
   4  * Released under terms in GPL version 2.  See COPYING.
   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
  36 enum 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_MAX,
  41 };
  42
  43 /* XDP flags for ndo_xdp_xmit */
  44 #define XDP_XMIT_FLAGS_NONE     0U
  45 #define XDP_XMIT_FLUSH          (1U << 0)       /* doorbell signal consumer */
  46 #define XDP_XMIT_FLAGS_MASK     XDP_XMIT_FLUSH
  47
  48 struct xdp_mem_info {
  49         u32 type; /* enum xdp_mem_type, but known size type */
  50         u32 id;
  51 };
  52
  53 struct page_pool;
  54
  55 struct xdp_rxq_info {
  56         struct net_device *dev;
  57         u32 queue_index;
  58         u32 reg_state;
  59         struct xdp_mem_info mem;
  60 } ____cacheline_aligned; /* perf critical, avoid false-sharing */
  61
  62 struct xdp_buff {
  63         void *data;
  64         void *data_end;
  65         void *data_meta;
  66         void *data_hard_start;
  67         struct xdp_rxq_info *rxq;
  68 };
  69
  70 struct xdp_frame {
  71         void *data;
  72         u16 len;
  73         u16 headroom;
  74         u16 metasize;
  75         /* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time,
  76          * while mem info is valid on remote CPU.
  77          */
  78         struct xdp_mem_info mem;
  79         struct net_device *dev_rx; /* used by cpumap */
  80 };
  81
  82 /* Convert xdp_buff to xdp_frame */
  83 static inline
  84 struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp)
  85 {
  86         struct xdp_frame *xdp_frame;
  87         int metasize;
  88         int headroom;
  89
  90         /* Assure headroom is available for storing info */
  91         headroom = xdp->data - xdp->data_hard_start;
  92         metasize = xdp->data - xdp->data_meta;
  93         metasize = metasize > 0 ? metasize : 0;
  94         if (unlikely((headroom - metasize) < sizeof(*xdp_frame)))
  95                 return NULL;
  96
  97         /* Store info in top of packet */
  98         xdp_frame = xdp->data_hard_start;
  99
 100         xdp_frame->data = xdp->data;
 101         xdp_frame->len  = xdp->data_end - xdp->data;
 102         xdp_frame->headroom = headroom - sizeof(*xdp_frame);
 103         xdp_frame->metasize = metasize;
 104
 105         /* rxq only valid until napi_schedule ends, convert to xdp_mem_info */
 106         xdp_frame->mem = xdp->rxq->mem;
 107
 108         return xdp_frame;
 109 }
 110
 111 void xdp_return_frame(struct xdp_frame *xdpf);
 112 void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);
 113 void xdp_return_buff(struct xdp_buff *xdp);
 114
 115 int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
 116                      struct net_device *dev, u32 queue_index);
 117 void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq);
 118 void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq);
 119 bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq);
 120 int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
 121                                enum xdp_mem_type type, void *allocator);
 122
 123 /* Drivers not supporting XDP metadata can use this helper, which
 124  * rejects any room expansion for metadata as a result.
 125  */
 126 static __always_inline void
 127 xdp_set_data_meta_invalid(struct xdp_buff *xdp)
 128 {
 129         xdp->data_meta = xdp->data + 1;
 130 }
 131
 132 static __always_inline bool
 133 xdp_data_meta_unsupported(const struct xdp_buff *xdp)
 134 {
 135         return unlikely(xdp->data_meta > xdp->data);
 136 }
 137
 138 #endif /* __LINUX_NET_XDP_H__ */