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 * Multiple transmit and receive queues: 55 * If supported, the backend will write the key "multi-queue-max-queues" to 56 * the directory for that vif, and set its value to the maximum supported 57 * number of queues. 58 * Frontends that are aware of this feature and wish to use it can write the 59 * key "multi-queue-num-queues", set to the number they wish to use, which 60 * must be greater than zero, and no more than the value reported by the backend 61 * in "multi-queue-max-queues". 62 * 63 * Queues replicate the shared rings and event channels. 64 * "feature-split-event-channels" may optionally be used when using 65 * multiple queues, but is not mandatory. 66 * 67 * Each queue consists of one shared ring pair, i.e. there must be the same 68 * number of tx and rx rings. 69 * 70 * For frontends requesting just one queue, the usual event-channel and 71 * ring-ref keys are written as before, simplifying the backend processing 72 * to avoid distinguishing between a frontend that doesn't understand the 73 * multi-queue feature, and one that does, but requested only one queue. 74 * 75 * Frontends requesting two or more queues must not write the toplevel 76 * event-channel (or event-channel-{tx,rx}) and {tx,rx}-ring-ref keys, 77 * instead writing those keys under sub-keys having the name "queue-N" where 78 * N is the integer ID of the queue for which those keys belong. Queues 79 * are indexed from zero. For example, a frontend with two queues and split 80 * event channels must write the following set of queue-related keys: 81 * 82 * /local/domain/1/device/vif/0/multi-queue-num-queues = "2" 83 * /local/domain/1/device/vif/0/queue-0 = "" 84 * /local/domain/1/device/vif/0/queue-0/tx-ring-ref = "<ring-ref-tx0>" 85 * /local/domain/1/device/vif/0/queue-0/rx-ring-ref = "<ring-ref-rx0>" 86 * /local/domain/1/device/vif/0/queue-0/event-channel-tx = "<evtchn-tx0>" 87 * /local/domain/1/device/vif/0/queue-0/event-channel-rx = "<evtchn-rx0>" 88 * /local/domain/1/device/vif/0/queue-1 = "" 89 * /local/domain/1/device/vif/0/queue-1/tx-ring-ref = "<ring-ref-tx1>" 90 * /local/domain/1/device/vif/0/queue-1/rx-ring-ref = "<ring-ref-rx1" 91 * /local/domain/1/device/vif/0/queue-1/event-channel-tx = "<evtchn-tx1>" 92 * /local/domain/1/device/vif/0/queue-1/event-channel-rx = "<evtchn-rx1>" 93 * 94 * If there is any inconsistency in the XenStore data, the backend may 95 * choose not to connect any queues, instead treating the request as an 96 * error. This includes scenarios where more (or fewer) queues were 97 * requested than the frontend provided details for. 98 * 99 * Mapping of packets to queues is considered to be a function of the 100 * transmitting system (backend or frontend) and is not negotiated 101 * between the two. Guests are free to transmit packets on any queue 102 * they choose, provided it has been set up correctly. Guests must be 103 * prepared to receive packets on any queue they have requested be set up. 104 */ 105 106 /* 107 * "feature-no-csum-offload" should be used to turn IPv4 TCP/UDP checksum 108 * offload off or on. If it is missing then the feature is assumed to be on. 109 * "feature-ipv6-csum-offload" should be used to turn IPv6 TCP/UDP checksum 110 * offload on or off. If it is missing then the feature is assumed to be off. 111 */ 112 113 /* 114 * "feature-gso-tcpv4" and "feature-gso-tcpv6" advertise the capability to 115 * handle large TCP packets (in IPv4 or IPv6 form respectively). Neither 116 * frontends nor backends are assumed to be capable unless the flags are 117 * present. 118 */ 119 120 /* 121 * This is the 'wire' format for packets: 122 * Request 1: xen_netif_tx_request -- XEN_NETTXF_* (any flags) 123 * [Request 2: xen_netif_extra_info] (only if request 1 has XEN_NETTXF_extra_info) 124 * [Request 3: xen_netif_extra_info] (only if request 2 has XEN_NETIF_EXTRA_MORE) 125 * Request 4: xen_netif_tx_request -- XEN_NETTXF_more_data 126 * Request 5: xen_netif_tx_request -- XEN_NETTXF_more_data 127 * ... 128 * Request N: xen_netif_tx_request -- 0 129 */ 130 131 /* Protocol checksum field is blank in the packet (hardware offload)? */ 132 #define _XEN_NETTXF_csum_blank (0) 133 #define XEN_NETTXF_csum_blank (1U<<_XEN_NETTXF_csum_blank) 134 135 /* Packet data has been validated against protocol checksum. */ 136 #define _XEN_NETTXF_data_validated (1) 137 #define XEN_NETTXF_data_validated (1U<<_XEN_NETTXF_data_validated) 138 139 /* Packet continues in the next request descriptor. */ 140 #define _XEN_NETTXF_more_data (2) 141 #define XEN_NETTXF_more_data (1U<<_XEN_NETTXF_more_data) 142 143 /* Packet to be followed by extra descriptor(s). */ 144 #define _XEN_NETTXF_extra_info (3) 145 #define XEN_NETTXF_extra_info (1U<<_XEN_NETTXF_extra_info) 146 147 #define XEN_NETIF_MAX_TX_SIZE 0xFFFF 148 struct xen_netif_tx_request { 149 grant_ref_t gref; /* Reference to buffer page */ 150 uint16_t offset; /* Offset within buffer page */ 151 uint16_t flags; /* XEN_NETTXF_* */ 152 uint16_t id; /* Echoed in response message. */ 153 uint16_t size; /* Packet size in bytes. */ 154 }; 155 156 /* Types of xen_netif_extra_info descriptors. */ 157 #define XEN_NETIF_EXTRA_TYPE_NONE (0) /* Never used - invalid */ 158 #define XEN_NETIF_EXTRA_TYPE_GSO (1) /* u.gso */ 159 #define XEN_NETIF_EXTRA_TYPE_MCAST_ADD (2) /* u.mcast */ 160 #define XEN_NETIF_EXTRA_TYPE_MCAST_DEL (3) /* u.mcast */ 161 #define XEN_NETIF_EXTRA_TYPE_MAX (4) 162 163 /* xen_netif_extra_info flags. */ 164 #define _XEN_NETIF_EXTRA_FLAG_MORE (0) 165 #define XEN_NETIF_EXTRA_FLAG_MORE (1U<<_XEN_NETIF_EXTRA_FLAG_MORE) 166 167 /* GSO types */ 168 #define XEN_NETIF_GSO_TYPE_NONE (0) 169 #define XEN_NETIF_GSO_TYPE_TCPV4 (1) 170 #define XEN_NETIF_GSO_TYPE_TCPV6 (2) 171 172 /* 173 * This structure needs to fit within both netif_tx_request and 174 * netif_rx_response for compatibility. 175 */ 176 struct xen_netif_extra_info { 177 uint8_t type; /* XEN_NETIF_EXTRA_TYPE_* */ 178 uint8_t flags; /* XEN_NETIF_EXTRA_FLAG_* */ 179 180 union { 181 struct { 182 /* 183 * Maximum payload size of each segment. For 184 * example, for TCP this is just the path MSS. 185 */ 186 uint16_t size; 187 188 /* 189 * GSO type. This determines the protocol of 190 * the packet and any extra features required 191 * to segment the packet properly. 192 */ 193 uint8_t type; /* XEN_NETIF_GSO_TYPE_* */ 194 195 /* Future expansion. */ 196 uint8_t pad; 197 198 /* 199 * GSO features. This specifies any extra GSO 200 * features required to process this packet, 201 * such as ECN support for TCPv4. 202 */ 203 uint16_t features; /* XEN_NETIF_GSO_FEAT_* */ 204 } gso; 205 206 struct { 207 uint8_t addr[6]; /* Address to add/remove. */ 208 } mcast; 209 210 uint16_t pad[3]; 211 } u; 212 }; 213 214 struct xen_netif_tx_response { 215 uint16_t id; 216 int16_t status; /* XEN_NETIF_RSP_* */ 217 }; 218 219 struct xen_netif_rx_request { 220 uint16_t id; /* Echoed in response message. */ 221 grant_ref_t gref; /* Reference to incoming granted frame */ 222 }; 223 224 /* Packet data has been validated against protocol checksum. */ 225 #define _XEN_NETRXF_data_validated (0) 226 #define XEN_NETRXF_data_validated (1U<<_XEN_NETRXF_data_validated) 227 228 /* Protocol checksum field is blank in the packet (hardware offload)? */ 229 #define _XEN_NETRXF_csum_blank (1) 230 #define XEN_NETRXF_csum_blank (1U<<_XEN_NETRXF_csum_blank) 231 232 /* Packet continues in the next request descriptor. */ 233 #define _XEN_NETRXF_more_data (2) 234 #define XEN_NETRXF_more_data (1U<<_XEN_NETRXF_more_data) 235 236 /* Packet to be followed by extra descriptor(s). */ 237 #define _XEN_NETRXF_extra_info (3) 238 #define XEN_NETRXF_extra_info (1U<<_XEN_NETRXF_extra_info) 239 240 /* GSO Prefix descriptor. */ 241 #define _XEN_NETRXF_gso_prefix (4) 242 #define XEN_NETRXF_gso_prefix (1U<<_XEN_NETRXF_gso_prefix) 243 244 struct xen_netif_rx_response { 245 uint16_t id; 246 uint16_t offset; /* Offset in page of start of received packet */ 247 uint16_t flags; /* XEN_NETRXF_* */ 248 int16_t status; /* -ve: BLKIF_RSP_* ; +ve: Rx'ed pkt size. */ 249 }; 250 251 /* 252 * Generate netif ring structures and types. 253 */ 254 255 DEFINE_RING_TYPES(xen_netif_tx, 256 struct xen_netif_tx_request, 257 struct xen_netif_tx_response); 258 DEFINE_RING_TYPES(xen_netif_rx, 259 struct xen_netif_rx_request, 260 struct xen_netif_rx_response); 261 262 #define XEN_NETIF_RSP_DROPPED -2 263 #define XEN_NETIF_RSP_ERROR -1 264 #define XEN_NETIF_RSP_OKAY 0 265 /* No response: used for auxiliary requests (e.g., xen_netif_extra_info). */ 266 #define XEN_NETIF_RSP_NULL 1 267 268 #endif 269