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"). 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/* Requests from the frontend to the backend */ 108 109/* 110 * Request a SCSI operation specified via a CDB in vscsiif_request.cmnd. 111 * The target is specified via channel, id and lun. 112 * 113 * The operation to be performed is specified via a CDB in cmnd[], the length 114 * of the CDB is in cmd_len. sc_data_direction specifies the direction of data 115 * (to the device, from the device, or none at all). 116 * 117 * If data is to be transferred to or from the device the buffer(s) in the 118 * guest memory is/are specified via one or multiple scsiif_request_segment 119 * descriptors each specifying a memory page via a grant_ref_t, a offset into 120 * the page and the length of the area in that page. All scsiif_request_segment 121 * areas concatenated form the resulting data buffer used by the operation. 122 * If the number of scsiif_request_segment areas is not too large (less than 123 * or equal VSCSIIF_SG_TABLESIZE) the areas can be specified directly in the 124 * seg[] array and the number of valid scsiif_request_segment elements is to be 125 * set in nr_segments. 126 * 127 * If "feature-sg-grant" in the Xenstore is set it is possible to specify more 128 * than VSCSIIF_SG_TABLESIZE scsiif_request_segment elements via indirection. 129 * The maximum number of allowed scsiif_request_segment elements is the value 130 * of the "feature-sg-grant" entry from Xenstore. When using indirection the 131 * seg[] array doesn't contain specifications of the data buffers, but 132 * references to scsiif_request_segment arrays, which in turn reference the 133 * data buffers. While nr_segments holds the number of populated seg[] entries 134 * (plus the set VSCSIIF_SG_GRANT bit), the number of scsiif_request_segment 135 * elements referencing the target data buffers is calculated from the lengths 136 * of the seg[] elements (the sum of all valid seg[].length divided by the 137 * size of one scsiif_request_segment structure). 138 */ 139#define VSCSIIF_ACT_SCSI_CDB 1 140 141/* 142 * Request abort of a running operation for the specified target given by 143 * channel, id, lun and the operation's rqid in ref_rqid. 144 */ 145#define VSCSIIF_ACT_SCSI_ABORT 2 146 147/* 148 * Request a device reset of the specified target (channel and id). 149 */ 150#define VSCSIIF_ACT_SCSI_RESET 3 151 152/* 153 * Preset scatter/gather elements for a following request. Deprecated. 154 * Keeping the define only to avoid usage of the value "4" for other actions. 155 */ 156#define VSCSIIF_ACT_SCSI_SG_PRESET 4 157 158/* 159 * Maximum scatter/gather segments per request. 160 * 161 * Considering balance between allocating at least 16 "vscsiif_request" 162 * structures on one page (4096 bytes) and the number of scatter/gather 163 * elements needed, we decided to use 26 as a magic number. 164 * 165 * If "feature-sg-grant" is set, more scatter/gather elements can be specified 166 * by placing them in one or more (up to VSCSIIF_SG_TABLESIZE) granted pages. 167 * In this case the vscsiif_request seg elements don't contain references to 168 * the user data, but to the SG elements referencing the user data. 169 */ 170#define VSCSIIF_SG_TABLESIZE 26 171 172/* 173 * based on Linux kernel 2.6.18, still valid 174 * Changing these values requires support of multiple protocols via the rings 175 * as "old clients" will blindly use these values and the resulting structure 176 * sizes. 177 */ 178#define VSCSIIF_MAX_COMMAND_SIZE 16 179#define VSCSIIF_SENSE_BUFFERSIZE 96 180 181struct scsiif_request_segment { 182 grant_ref_t gref; 183 uint16_t offset; 184 uint16_t length; 185}; 186 187#define VSCSIIF_SG_PER_PAGE (PAGE_SIZE / sizeof(struct scsiif_request_segment)) 188 189/* Size of one request is 252 bytes */ 190struct vscsiif_request { 191 uint16_t rqid; /* private guest value, echoed in resp */ 192 uint8_t act; /* command between backend and frontend */ 193 uint8_t cmd_len; /* valid CDB bytes */ 194 195 uint8_t cmnd[VSCSIIF_MAX_COMMAND_SIZE]; /* the CDB */ 196 uint16_t timeout_per_command; /* deprecated */ 197 uint16_t channel, id, lun; /* (virtual) device specification */ 198 uint16_t ref_rqid; /* command abort reference */ 199 uint8_t sc_data_direction; /* for DMA_TO_DEVICE(1) 200 DMA_FROM_DEVICE(2) 201 DMA_NONE(3) requests */ 202 uint8_t nr_segments; /* Number of pieces of scatter-gather */ 203/* 204 * flag in nr_segments: SG elements via grant page 205 * 206 * If VSCSIIF_SG_GRANT is set, the low 7 bits of nr_segments specify the number 207 * of grant pages containing SG elements. Usable if "feature-sg-grant" set. 208 */ 209#define VSCSIIF_SG_GRANT 0x80 210 211 struct scsiif_request_segment seg[VSCSIIF_SG_TABLESIZE]; 212 uint32_t reserved[3]; 213}; 214 215/* Size of one response is 252 bytes */ 216struct vscsiif_response { 217 uint16_t rqid; /* identifies request */ 218 uint8_t padding; 219 uint8_t sense_len; 220 uint8_t sense_buffer[VSCSIIF_SENSE_BUFFERSIZE]; 221 int32_t rslt; 222 uint32_t residual_len; /* request bufflen - 223 return the value from physical device */ 224 uint32_t reserved[36]; 225}; 226 227DEFINE_RING_TYPES(vscsiif, struct vscsiif_request, struct vscsiif_response); 228 229#endif /*__XEN__PUBLIC_IO_SCSI_H__*/ 230