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 148struct 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_MAX (2) 160 161/* xen_netif_extra_info flags. */ 162#define _XEN_NETIF_EXTRA_FLAG_MORE (0) 163#define XEN_NETIF_EXTRA_FLAG_MORE (1U<<_XEN_NETIF_EXTRA_FLAG_MORE) 164 165/* GSO types */ 166#define XEN_NETIF_GSO_TYPE_NONE (0) 167#define XEN_NETIF_GSO_TYPE_TCPV4 (1) 168#define XEN_NETIF_GSO_TYPE_TCPV6 (2) 169 170/* 171 * This structure needs to fit within both netif_tx_request and 172 * netif_rx_response for compatibility. 173 */ 174struct xen_netif_extra_info { 175 uint8_t type; /* XEN_NETIF_EXTRA_TYPE_* */ 176 uint8_t flags; /* XEN_NETIF_EXTRA_FLAG_* */ 177 178 union { 179 struct { 180 /* 181 * Maximum payload size of each segment. For 182 * example, for TCP this is just the path MSS. 183 */ 184 uint16_t size; 185 186 /* 187 * GSO type. This determines the protocol of 188 * the packet and any extra features required 189 * to segment the packet properly. 190 */ 191 uint8_t type; /* XEN_NETIF_GSO_TYPE_* */ 192 193 /* Future expansion. */ 194 uint8_t pad; 195 196 /* 197 * GSO features. This specifies any extra GSO 198 * features required to process this packet, 199 * such as ECN support for TCPv4. 200 */ 201 uint16_t features; /* XEN_NETIF_GSO_FEAT_* */ 202 } gso; 203 204 uint16_t pad[3]; 205 } u; 206}; 207 208struct xen_netif_tx_response { 209 uint16_t id; 210 int16_t status; /* XEN_NETIF_RSP_* */ 211}; 212 213struct xen_netif_rx_request { 214 uint16_t id; /* Echoed in response message. */ 215 grant_ref_t gref; /* Reference to incoming granted frame */ 216}; 217 218/* Packet data has been validated against protocol checksum. */ 219#define _XEN_NETRXF_data_validated (0) 220#define XEN_NETRXF_data_validated (1U<<_XEN_NETRXF_data_validated) 221 222/* Protocol checksum field is blank in the packet (hardware offload)? */ 223#define _XEN_NETRXF_csum_blank (1) 224#define XEN_NETRXF_csum_blank (1U<<_XEN_NETRXF_csum_blank) 225 226/* Packet continues in the next request descriptor. */ 227#define _XEN_NETRXF_more_data (2) 228#define XEN_NETRXF_more_data (1U<<_XEN_NETRXF_more_data) 229 230/* Packet to be followed by extra descriptor(s). */ 231#define _XEN_NETRXF_extra_info (3) 232#define XEN_NETRXF_extra_info (1U<<_XEN_NETRXF_extra_info) 233 234/* GSO Prefix descriptor. */ 235#define _XEN_NETRXF_gso_prefix (4) 236#define XEN_NETRXF_gso_prefix (1U<<_XEN_NETRXF_gso_prefix) 237 238struct xen_netif_rx_response { 239 uint16_t id; 240 uint16_t offset; /* Offset in page of start of received packet */ 241 uint16_t flags; /* XEN_NETRXF_* */ 242 int16_t status; /* -ve: BLKIF_RSP_* ; +ve: Rx'ed pkt size. */ 243}; 244 245/* 246 * Generate netif ring structures and types. 247 */ 248 249DEFINE_RING_TYPES(xen_netif_tx, 250 struct xen_netif_tx_request, 251 struct xen_netif_tx_response); 252DEFINE_RING_TYPES(xen_netif_rx, 253 struct xen_netif_rx_request, 254 struct xen_netif_rx_response); 255 256#define XEN_NETIF_RSP_DROPPED -2 257#define XEN_NETIF_RSP_ERROR -1 258#define XEN_NETIF_RSP_OKAY 0 259/* No response: used for auxiliary requests (e.g., xen_netif_extra_info). */ 260#define XEN_NETIF_RSP_NULL 1 261 262#endif 263