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_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
  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 zero_copy_allocator {
  56         void (*free)(struct zero_copy_allocator *zca, unsigned long handle);
  57 };
  58
  59 struct 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
  66 struct 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
  75 struct 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 */
  88 static inline void xdp_scrub_frame(struct xdp_frame *frame)
  89 {
  90         frame->data = NULL;
  91         frame->dev_rx = NULL;
  92 }
  93
  94 /* Convert xdp_buff to xdp_frame */
  95 static inline
  96 struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp)
  97 {
  98         struct xdp_frame *xdp_frame;
  99         int metasize;
 100         int headroom;
 101
 102         /* TODO: implement clone, copy, use "native" MEM_TYPE */
 103         if (xdp->rxq->mem.type == MEM_TYPE_ZERO_COPY)
 104                 return NULL;
 105
 106         /* Assure headroom is available for storing info */
 107         headroom = xdp->data - xdp->data_hard_start;
 108         metasize = xdp->data - xdp->data_meta;
 109         metasize = metasize > 0 ? metasize : 0;
 110         if (unlikely((headroom - metasize) < sizeof(*xdp_frame)))
 111                 return NULL;
 112
 113         /* Store info in top of packet */
 114         xdp_frame = xdp->data_hard_start;
 115
 116         xdp_frame->data = xdp->data;
 117         xdp_frame->len  = xdp->data_end - xdp->data;
 118         xdp_frame->headroom = headroom - sizeof(*xdp_frame);
 119         xdp_frame->metasize = metasize;
 120
 121         /* rxq only valid until napi_schedule ends, convert to xdp_mem_info */
 122         xdp_frame->mem = xdp->rxq->mem;
 123
 124         return xdp_frame;
 125 }
 126
 127 void xdp_return_frame(struct xdp_frame *xdpf);
 128 void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);
 129 void xdp_return_buff(struct xdp_buff *xdp);
 130
 131 int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
 132                      struct net_device *dev, u32 queue_index);
 133 void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq);
 134 void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq);
 135 bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq);
 136 int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
 137                                enum xdp_mem_type type, void *allocator);
 138
 139 /* Drivers not supporting XDP metadata can use this helper, which
 140  * rejects any room expansion for metadata as a result.
 141  */
 142 static __always_inline void
 143 xdp_set_data_meta_invalid(struct xdp_buff *xdp)
 144 {
 145         xdp->data_meta = xdp->data + 1;
 146 }
 147
 148 static __always_inline bool
 149 xdp_data_meta_unsupported(const struct xdp_buff *xdp)
 150 {
 151         return unlikely(xdp->data_meta > xdp->data);
 152 }
 153
 154 struct xdp_attachment_info {
 155         struct bpf_prog *prog;
 156         u32 flags;
 157 };
 158
 159 struct netdev_bpf;
 160 int xdp_attachment_query(struct xdp_attachment_info *info,
 161                          struct netdev_bpf *bpf);
 162 bool xdp_attachment_flags_ok(struct xdp_attachment_info *info,
 163                              struct netdev_bpf *bpf);
 164 void xdp_attachment_setup(struct xdp_attachment_info *info,
 165                           struct netdev_bpf *bpf);
 166
 167 #endif /* __LINUX_NET_XDP_H__ */