1 /****************************************************************************** 2 * vscsiif.h 3 * 4 * Based on the blkif.h code. 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a copy 7 * of this software and associated documentation files (the "Software"), to 8 * deal in the Software without restriction, including without limitation the 9 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or 10 * sell copies of the Software, and to permit persons to whom the Software is 11 * furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 21 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 22 * DEALINGS IN THE SOFTWARE. 23 * 24 * Copyright(c) FUJITSU Limited 2008. 25 */ 26 27 #ifndef __XEN__PUBLIC_IO_SCSI_H__ 28 #define __XEN__PUBLIC_IO_SCSI_H__ 29 30 #include "ring.h" 31 #include "../grant_table.h" 32 33 /* 34 * Feature and Parameter Negotiation 35 * ================================= 36 * The two halves of a Xen pvSCSI driver utilize nodes within the XenStore to 37 * communicate capabilities and to negotiate operating parameters. This 38 * section enumerates these nodes which reside in the respective front and 39 * backend portions of the XenStore, following the XenBus convention. 40 * 41 * Any specified default value is in effect if the corresponding XenBus node 42 * is not present in the XenStore. 43 * 44 * XenStore nodes in sections marked "PRIVATE" are solely for use by the 45 * driver side whose XenBus tree contains them. 46 * 47 ***************************************************************************** 48 * Backend XenBus Nodes 49 ***************************************************************************** 50 * 51 *------------------ Backend Device Identification (PRIVATE) ------------------ 52 * 53 * p-devname 54 * Values: string 55 * 56 * A free string used to identify the physical device (e.g. a disk name). 57 * 58 * p-dev 59 * Values: string 60 * 61 * A string specifying the backend device: either a 4-tuple "h:c:t:l" 62 * (host, controller, target, lun, all integers), or a WWN (e.g. 63 * "naa.60014054ac780582:0"). 64 * 65 * v-dev 66 * Values: string 67 * 68 * A string specifying the frontend device in form of a 4-tuple "h:c:t:l" 69 * (host, controller, target, lun, all integers). 70 * 71 *--------------------------------- Features --------------------------------- 72 * 73 * feature-sg-grant 74 * Values: unsigned [VSCSIIF_SG_TABLESIZE...65535] 75 * Default Value: 0 76 * 77 * Specifies the maximum number of scatter/gather elements in grant pages 78 * supported. If not set, the backend supports up to VSCSIIF_SG_TABLESIZE 79 * SG elements specified directly in the request. 80 * 81 ***************************************************************************** 82 * Frontend XenBus Nodes 83 ***************************************************************************** 84 * 85 *----------------------- Request Transport Parameters ----------------------- 86 * 87 * event-channel 88 * Values: unsigned 89 * 90 * The identifier of the Xen event channel used to signal activity 91 * in the ring buffer. 92 * 93 * ring-ref 94 * Values: unsigned 95 * 96 * The Xen grant reference granting permission for the backend to map 97 * the sole page in a single page sized ring buffer. 98 * 99 * protocol 100 * Values: string (XEN_IO_PROTO_ABI_*) 101 * Default Value: XEN_IO_PROTO_ABI_NATIVE 102 * 103 * The machine ABI rules governing the format of all ring request and 104 * response structures. 105 */ 106 107 /* 108 * Xenstore format in practice 109 * =========================== 110 * 111 * The backend driver uses a single_host:many_devices notation to manage domU 112 * devices. Everything is stored in /local/domain/<backend_domid>/backend/vscsi/. 113 * The xenstore layout looks like this (dom0 is assumed to be the backend_domid): 114 * 115 * <domid>/<vhost>/feature-host = "0" 116 * <domid>/<vhost>/frontend = "/local/domain/<domid>/device/vscsi/0" 117 * <domid>/<vhost>/frontend-id = "<domid>" 118 * <domid>/<vhost>/online = "1" 119 * <domid>/<vhost>/state = "4" 120 * <domid>/<vhost>/vscsi-devs/dev-0/p-dev = "8:0:2:1" or "naa.wwn:lun" 121 * <domid>/<vhost>/vscsi-devs/dev-0/state = "4" 122 * <domid>/<vhost>/vscsi-devs/dev-0/v-dev = "0:0:0:0" 123 * <domid>/<vhost>/vscsi-devs/dev-1/p-dev = "8:0:2:2" 124 * <domid>/<vhost>/vscsi-devs/dev-1/state = "4" 125 * <domid>/<vhost>/vscsi-devs/dev-1/v-dev = "0:0:1:0" 126 * 127 * The frontend driver maintains its state in 128 * /local/domain/<domid>/device/vscsi/. 129 * 130 * <vhost>/backend = "/local/domain/0/backend/vscsi/<domid>/<vhost>" 131 * <vhost>/backend-id = "0" 132 * <vhost>/event-channel = "20" 133 * <vhost>/ring-ref = "43" 134 * <vhost>/state = "4" 135 * <vhost>/vscsi-devs/dev-0/state = "4" 136 * <vhost>/vscsi-devs/dev-1/state = "4" 137 * 138 * In addition to the entries for backend and frontend these flags are stored 139 * for the toolstack: 140 * 141 * <domid>/<vhost>/vscsi-devs/dev-1/p-devname = "/dev/$device" 142 * <domid>/<vhost>/libxl_ctrl_index = "0" 143 * 144 * 145 * Backend/frontend protocol 146 * ========================= 147 * 148 * To create a vhost along with a device: 149 * <domid>/<vhost>/feature-host = "0" 150 * <domid>/<vhost>/frontend = "/local/domain/<domid>/device/vscsi/0" 151 * <domid>/<vhost>/frontend-id = "<domid>" 152 * <domid>/<vhost>/online = "1" 153 * <domid>/<vhost>/state = "1" 154 * <domid>/<vhost>/vscsi-devs/dev-0/p-dev = "8:0:2:1" 155 * <domid>/<vhost>/vscsi-devs/dev-0/state = "1" 156 * <domid>/<vhost>/vscsi-devs/dev-0/v-dev = "0:0:0:0" 157 * Wait for <domid>/<vhost>/state + <domid>/<vhost>/vscsi-devs/dev-0/state become 4 158 * 159 * To add another device to a vhost: 160 * <domid>/<vhost>/state = "7" 161 * <domid>/<vhost>/vscsi-devs/dev-1/p-dev = "8:0:2:2" 162 * <domid>/<vhost>/vscsi-devs/dev-1/state = "1" 163 * <domid>/<vhost>/vscsi-devs/dev-1/v-dev = "0:0:1:0" 164 * Wait for <domid>/<vhost>/state + <domid>/<vhost>/vscsi-devs/dev-1/state become 4 165 * 166 * To remove a device from a vhost: 167 * <domid>/<vhost>/state = "7" 168 * <domid>/<vhost>/vscsi-devs/dev-1/state = "5" 169 * Wait for <domid>/<vhost>/state to become 4 170 * Wait for <domid>/<vhost>/vscsi-devs/dev-1/state become 6 171 * Remove <domid>/<vhost>/vscsi-devs/dev-1/{state,p-dev,v-dev,p-devname} 172 * Remove <domid>/<vhost>/vscsi-devs/dev-1/ 173 * 174 */ 175 176 /* Requests from the frontend to the backend */ 177 178 /* 179 * Request a SCSI operation specified via a CDB in vscsiif_request.cmnd. 180 * The target is specified via channel, id and lun. 181 * 182 * The operation to be performed is specified via a CDB in cmnd[], the length 183 * of the CDB is in cmd_len. sc_data_direction specifies the direction of data 184 * (to the device, from the device, or none at all). 185 * 186 * If data is to be transferred to or from the device the buffer(s) in the 187 * guest memory is/are specified via one or multiple scsiif_request_segment 188 * descriptors each specifying a memory page via a grant_ref_t, a offset into 189 * the page and the length of the area in that page. All scsiif_request_segment 190 * areas concatenated form the resulting data buffer used by the operation. 191 * If the number of scsiif_request_segment areas is not too large (less than 192 * or equal VSCSIIF_SG_TABLESIZE) the areas can be specified directly in the 193 * seg[] array and the number of valid scsiif_request_segment elements is to be 194 * set in nr_segments. 195 * 196 * If "feature-sg-grant" in the Xenstore is set it is possible to specify more 197 * than VSCSIIF_SG_TABLESIZE scsiif_request_segment elements via indirection. 198 * The maximum number of allowed scsiif_request_segment elements is the value 199 * of the "feature-sg-grant" entry from Xenstore. When using indirection the 200 * seg[] array doesn't contain specifications of the data buffers, but 201 * references to scsiif_request_segment arrays, which in turn reference the 202 * data buffers. While nr_segments holds the number of populated seg[] entries 203 * (plus the set VSCSIIF_SG_GRANT bit), the number of scsiif_request_segment 204 * elements referencing the target data buffers is calculated from the lengths 205 * of the seg[] elements (the sum of all valid seg[].length divided by the 206 * size of one scsiif_request_segment structure). The frontend may use a mix of 207 * direct and indirect requests. 208 */ 209 #define VSCSIIF_ACT_SCSI_CDB 1 210 211 /* 212 * Request abort of a running operation for the specified target given by 213 * channel, id, lun and the operation's rqid in ref_rqid. 214 */ 215 #define VSCSIIF_ACT_SCSI_ABORT 2 216 217 /* 218 * Request a device reset of the specified target (channel and id). 219 */ 220 #define VSCSIIF_ACT_SCSI_RESET 3 221 222 /* 223 * Preset scatter/gather elements for a following request. Deprecated. 224 * Keeping the define only to avoid usage of the value "4" for other actions. 225 */ 226 #define VSCSIIF_ACT_SCSI_SG_PRESET 4 227 228 /* 229 * Maximum scatter/gather segments per request. 230 * 231 * Considering balance between allocating at least 16 "vscsiif_request" 232 * structures on one page (4096 bytes) and the number of scatter/gather 233 * elements needed, we decided to use 26 as a magic number. 234 * 235 * If "feature-sg-grant" is set, more scatter/gather elements can be specified 236 * by placing them in one or more (up to VSCSIIF_SG_TABLESIZE) granted pages. 237 * In this case the vscsiif_request seg elements don't contain references to 238 * the user data, but to the SG elements referencing the user data. 239 */ 240 #define VSCSIIF_SG_TABLESIZE 26 241 242 /* 243 * based on Linux kernel 2.6.18, still valid 244 * 245 * Changing these values requires support of multiple protocols via the rings 246 * as "old clients" will blindly use these values and the resulting structure 247 * sizes. 248 */ 249 #define VSCSIIF_MAX_COMMAND_SIZE 16 250 #define VSCSIIF_SENSE_BUFFERSIZE 96 251 #define VSCSIIF_PAGE_SIZE 4096 252 253 struct scsiif_request_segment { 254 grant_ref_t gref; 255 uint16_t offset; 256 uint16_t length; 257 }; 258 typedef struct scsiif_request_segment vscsiif_segment_t; 259 260 #define VSCSIIF_SG_PER_PAGE (VSCSIIF_PAGE_SIZE / sizeof(struct scsiif_request_segment)) 261 262 /* Size of one request is 252 bytes */ 263 struct vscsiif_request { 264 uint16_t rqid; /* private guest value, echoed in resp */ 265 uint8_t act; /* command between backend and frontend */ 266 uint8_t cmd_len; /* valid CDB bytes */ 267 268 uint8_t cmnd[VSCSIIF_MAX_COMMAND_SIZE]; /* the CDB */ 269 uint16_t timeout_per_command; /* deprecated: timeout in secs, 0=default */ 270 uint16_t channel, id, lun; /* (virtual) device specification */ 271 uint16_t ref_rqid; /* command abort reference */ 272 uint8_t sc_data_direction; /* for DMA_TO_DEVICE(1) 273 DMA_FROM_DEVICE(2) 274 DMA_NONE(3) requests */ 275 uint8_t nr_segments; /* Number of pieces of scatter-gather */ 276 /* 277 * flag in nr_segments: SG elements via grant page 278 * 279 * If VSCSIIF_SG_GRANT is set, the low 7 bits of nr_segments specify the number 280 * of grant pages containing SG elements. Usable if "feature-sg-grant" set. 281 */ 282 #define VSCSIIF_SG_GRANT 0x80 283 284 vscsiif_segment_t seg[VSCSIIF_SG_TABLESIZE]; 285 uint32_t reserved[3]; 286 }; 287 typedef struct vscsiif_request vscsiif_request_t; 288 289 /* 290 * The following interface is deprecated! 291 */ 292 #define VSCSIIF_SG_LIST_SIZE ((sizeof(vscsiif_request_t) - 4) \ 293 / sizeof(vscsiif_segment_t)) 294 295 struct vscsiif_sg_list { 296 /* First two fields must match struct vscsiif_request! */ 297 uint16_t rqid; /* private guest value, must match main req */ 298 uint8_t act; /* VSCSIIF_ACT_SCSI_SG_PRESET */ 299 uint8_t nr_segments; /* Number of pieces of scatter-gather */ 300 vscsiif_segment_t seg[VSCSIIF_SG_LIST_SIZE]; 301 }; 302 typedef struct vscsiif_sg_list vscsiif_sg_list_t; 303 /* End of deprecated interface */ 304 305 /* Size of one response is 252 bytes */ 306 struct vscsiif_response { 307 uint16_t rqid; /* identifies request */ 308 uint8_t act; /* deprecated: valid only if SG_PRESET supported */ 309 uint8_t sense_len; 310 uint8_t sense_buffer[VSCSIIF_SENSE_BUFFERSIZE]; 311 int32_t rslt; 312 uint32_t residual_len; /* request bufflen - 313 return the value from physical device */ 314 uint32_t reserved[36]; 315 }; 316 typedef struct vscsiif_response vscsiif_response_t; 317 318 DEFINE_RING_TYPES(vscsiif, struct vscsiif_request, struct vscsiif_response); 319 320 321 #endif /*__XEN__PUBLIC_IO_SCSI_H__*/ 322 /* 323 * Local variables: 324 * mode: C 325 * c-file-style: "BSD" 326 * c-basic-offset: 4 327 * tab-width: 4 328 * indent-tabs-mode: nil 329 * End: 330 */ 331