include/xen/interface/io/netif.h

   1 /******************************************************************************
   2  * netif.h
   3  *
   4  * Unified network-device I/O interface for Xen guest OSes.
   5  *
   6  * Copyright (c) 2003-2004, Keir Fraser
   7  */
   8
   9 #ifndef __XEN_PUBLIC_IO_NETIF_H__
  10 #define __XEN_PUBLIC_IO_NETIF_H__
  11
  12 #include <xen/interface/io/ring.h>
  13 #include <xen/interface/grant_table.h>
  14
  15 /*
  16  * Older implementation of Xen network frontend / backend has an
  17  * implicit dependency on the MAX_SKB_FRAGS as the maximum number of
  18  * ring slots a skb can use. Netfront / netback may not work as
  19  * expected when frontend and backend have different MAX_SKB_FRAGS.
  20  *
  21  * A better approach is to add mechanism for netfront / netback to
  22  * negotiate this value. However we cannot fix all possible
  23  * frontends, so we need to define a value which states the minimum
  24  * slots backend must support.
  25  *
  26  * The minimum value derives from older Linux kernel's MAX_SKB_FRAGS
  27  * (18), which is proved to work with most frontends. Any new backend
  28  * which doesn't negotiate with frontend should expect frontend to
  29  * send a valid packet using slots up to this value.
  30  */
  31 #define XEN_NETIF_NR_SLOTS_MIN 18
  32
  33 /*
  34  * Notifications after enqueuing any type of message should be conditional on
  35  * the appropriate req_event or rsp_event field in the shared ring.
  36  * If the client sends notification for rx requests then it should specify
  37  * feature 'feature-rx-notify' via xenbus. Otherwise the backend will assume
  38  * that it cannot safely queue packets (as it may not be kicked to send them).
  39  */
  40
  41  /*
  42  * "feature-split-event-channels" is introduced to separate guest TX
  43  * and RX notificaion. Backend either doesn't support this feature or
  44  * advertise it via xenstore as 0 (disabled) or 1 (enabled).
  45  *
  46  * To make use of this feature, frontend should allocate two event
  47  * channels for TX and RX, advertise them to backend as
  48  * "event-channel-tx" and "event-channel-rx" respectively. If frontend
  49  * doesn't want to use this feature, it just writes "event-channel"
  50  * node as before.
  51  */
  52
  53 /*
  54  * This is the 'wire' format for packets:
  55  *  Request 1: xen_netif_tx_request  -- XEN_NETTXF_* (any flags)
  56  * [Request 2: xen_netif_extra_info]    (only if request 1 has XEN_NETTXF_extra_info)
  57  * [Request 3: xen_netif_extra_info]    (only if request 2 has XEN_NETIF_EXTRA_MORE)
  58  *  Request 4: xen_netif_tx_request  -- XEN_NETTXF_more_data
  59  *  Request 5: xen_netif_tx_request  -- XEN_NETTXF_more_data
  60  *  ...
  61  *  Request N: xen_netif_tx_request  -- 0
  62  */
  63
  64 /* Protocol checksum field is blank in the packet (hardware offload)? */
  65 #define _XEN_NETTXF_csum_blank          (0)
  66 #define  XEN_NETTXF_csum_blank          (1U<<_XEN_NETTXF_csum_blank)
  67
  68 /* Packet data has been validated against protocol checksum. */
  69 #define _XEN_NETTXF_data_validated      (1)
  70 #define  XEN_NETTXF_data_validated      (1U<<_XEN_NETTXF_data_validated)
  71
  72 /* Packet continues in the next request descriptor. */
  73 #define _XEN_NETTXF_more_data           (2)
  74 #define  XEN_NETTXF_more_data           (1U<<_XEN_NETTXF_more_data)
  75
  76 /* Packet to be followed by extra descriptor(s). */
  77 #define _XEN_NETTXF_extra_info          (3)
  78 #define  XEN_NETTXF_extra_info          (1U<<_XEN_NETTXF_extra_info)
  79
  80 #define XEN_NETIF_MAX_TX_SIZE 0xFFFF
  81 struct xen_netif_tx_request {
  82     grant_ref_t gref;      /* Reference to buffer page */
  83     uint16_t offset;       /* Offset within buffer page */
  84     uint16_t flags;        /* XEN_NETTXF_* */
  85     uint16_t id;           /* Echoed in response message. */
  86     uint16_t size;         /* Packet size in bytes.       */
  87 };
  88
  89 /* Types of xen_netif_extra_info descriptors. */
  90 #define XEN_NETIF_EXTRA_TYPE_NONE       (0)  /* Never used - invalid */
  91 #define XEN_NETIF_EXTRA_TYPE_GSO        (1)  /* u.gso */
  92 #define XEN_NETIF_EXTRA_TYPE_MAX        (2)
  93
  94 /* xen_netif_extra_info flags. */
  95 #define _XEN_NETIF_EXTRA_FLAG_MORE      (0)
  96 #define  XEN_NETIF_EXTRA_FLAG_MORE      (1U<<_XEN_NETIF_EXTRA_FLAG_MORE)
  97
  98 /* GSO types - only TCPv4 currently supported. */
  99 #define XEN_NETIF_GSO_TYPE_TCPV4        (1)
 100
 101 /*
 102  * This structure needs to fit within both netif_tx_request and
 103  * netif_rx_response for compatibility.
 104  */
 105 struct xen_netif_extra_info {
 106         uint8_t type;  /* XEN_NETIF_EXTRA_TYPE_* */
 107         uint8_t flags; /* XEN_NETIF_EXTRA_FLAG_* */
 108
 109         union {
 110                 struct {
 111                         /*
 112                          * Maximum payload size of each segment. For
 113                          * example, for TCP this is just the path MSS.
 114                          */
 115                         uint16_t size;
 116
 117                         /*
 118                          * GSO type. This determines the protocol of
 119                          * the packet and any extra features required
 120                          * to segment the packet properly.
 121                          */
 122                         uint8_t type; /* XEN_NETIF_GSO_TYPE_* */
 123
 124                         /* Future expansion. */
 125                         uint8_t pad;
 126
 127                         /*
 128                          * GSO features. This specifies any extra GSO
 129                          * features required to process this packet,
 130                          * such as ECN support for TCPv4.
 131                          */
 132                         uint16_t features; /* XEN_NETIF_GSO_FEAT_* */
 133                 } gso;
 134
 135                 uint16_t pad[3];
 136         } u;
 137 };
 138
 139 struct xen_netif_tx_response {
 140         uint16_t id;
 141         int16_t  status;       /* XEN_NETIF_RSP_* */
 142 };
 143
 144 struct xen_netif_rx_request {
 145         uint16_t    id;        /* Echoed in response message.        */
 146         grant_ref_t gref;      /* Reference to incoming granted frame */
 147 };
 148
 149 /* Packet data has been validated against protocol checksum. */
 150 #define _XEN_NETRXF_data_validated      (0)
 151 #define  XEN_NETRXF_data_validated      (1U<<_XEN_NETRXF_data_validated)
 152
 153 /* Protocol checksum field is blank in the packet (hardware offload)? */
 154 #define _XEN_NETRXF_csum_blank          (1)
 155 #define  XEN_NETRXF_csum_blank          (1U<<_XEN_NETRXF_csum_blank)
 156
 157 /* Packet continues in the next request descriptor. */
 158 #define _XEN_NETRXF_more_data           (2)
 159 #define  XEN_NETRXF_more_data           (1U<<_XEN_NETRXF_more_data)
 160
 161 /* Packet to be followed by extra descriptor(s). */
 162 #define _XEN_NETRXF_extra_info          (3)
 163 #define  XEN_NETRXF_extra_info          (1U<<_XEN_NETRXF_extra_info)
 164
 165 /* GSO Prefix descriptor. */
 166 #define _XEN_NETRXF_gso_prefix          (4)
 167 #define  XEN_NETRXF_gso_prefix          (1U<<_XEN_NETRXF_gso_prefix)
 168
 169 struct xen_netif_rx_response {
 170     uint16_t id;
 171     uint16_t offset;       /* Offset in page of start of received packet  */
 172     uint16_t flags;        /* XEN_NETRXF_* */
 173     int16_t  status;       /* -ve: BLKIF_RSP_* ; +ve: Rx'ed pkt size. */
 174 };
 175
 176 /*
 177  * Generate netif ring structures and types.
 178  */
 179
 180 DEFINE_RING_TYPES(xen_netif_tx,
 181                   struct xen_netif_tx_request,
 182                   struct xen_netif_tx_response);
 183 DEFINE_RING_TYPES(xen_netif_rx,
 184                   struct xen_netif_rx_request,
 185                   struct xen_netif_rx_response);
 186
 187 #define XEN_NETIF_RSP_DROPPED   -2
 188 #define XEN_NETIF_RSP_ERROR     -1
 189 #define XEN_NETIF_RSP_OKAY       0
 190 /* No response: used for auxiliary requests (e.g., xen_netif_extra_info). */
 191 #define XEN_NETIF_RSP_NULL       1
 192
 193 #endif