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 194