1 /* SPDX-License-Identifier: MIT */ 2 /****************************************************************************** 3 * vscsiif.h 4 * 5 * Based on the blkif.h code. 6 * 7 * Copyright(c) FUJITSU Limited 2008. 8 */ 9 10 #ifndef __XEN__PUBLIC_IO_SCSI_H__ 11 #define __XEN__PUBLIC_IO_SCSI_H__ 12 13 #include "ring.h" 14 #include "../grant_table.h" 15 16 /* 17 * Feature and Parameter Negotiation 18 * ================================= 19 * The two halves of a Xen pvSCSI driver utilize nodes within the XenStore to 20 * communicate capabilities and to negotiate operating parameters. This 21 * section enumerates these nodes which reside in the respective front and 22 * backend portions of the XenStore, following the XenBus convention. 23 * 24 * Any specified default value is in effect if the corresponding XenBus node 25 * is not present in the XenStore. 26 * 27 * XenStore nodes in sections marked "PRIVATE" are solely for use by the 28 * driver side whose XenBus tree contains them. 29 * 30 ***************************************************************************** 31 * Backend XenBus Nodes 32 ***************************************************************************** 33 * 34 *------------------ Backend Device Identification (PRIVATE) ------------------ 35 * 36 * p-devname 37 * Values: string 38 * 39 * A free string used to identify the physical device (e.g. a disk name). 40 * 41 * p-dev 42 * Values: string 43 * 44 * A string specifying the backend device: either a 4-tuple "h:c:t:l" 45 * (host, controller, target, lun, all integers), or a WWN (e.g. 46 * "naa.60014054ac780582"). 47 * 48 * v-dev 49 * Values: string 50 * 51 * A string specifying the frontend device in form of a 4-tuple "h:c:t:l" 52 * (host, controller, target, lun, all integers). 53 * 54 *--------------------------------- Features --------------------------------- 55 * 56 * feature-sg-grant 57 * Values: unsigned [VSCSIIF_SG_TABLESIZE...65535] 58 * Default Value: 0 59 * 60 * Specifies the maximum number of scatter/gather elements in grant pages 61 * supported. If not set, the backend supports up to VSCSIIF_SG_TABLESIZE 62 * SG elements specified directly in the request. 63 * 64 ***************************************************************************** 65 * Frontend XenBus Nodes 66 ***************************************************************************** 67 * 68 *----------------------- Request Transport Parameters ----------------------- 69 * 70 * event-channel 71 * Values: unsigned 72 * 73 * The identifier of the Xen event channel used to signal activity 74 * in the ring buffer. 75 * 76 * ring-ref 77 * Values: unsigned 78 * 79 * The Xen grant reference granting permission for the backend to map 80 * the sole page in a single page sized ring buffer. 81 * 82 * protocol 83 * Values: string (XEN_IO_PROTO_ABI_*) 84 * Default Value: XEN_IO_PROTO_ABI_NATIVE 85 * 86 * The machine ABI rules governing the format of all ring request and 87 * response structures. 88 */ 89 90 /* Requests from the frontend to the backend */ 91 92 /* 93 * Request a SCSI operation specified via a CDB in vscsiif_request.cmnd. 94 * The target is specified via channel, id and lun. 95 * 96 * The operation to be performed is specified via a CDB in cmnd[], the length 97 * of the CDB is in cmd_len. sc_data_direction specifies the direction of data 98 * (to the device, from the device, or none at all). 99 * 100 * If data is to be transferred to or from the device the buffer(s) in the 101 * guest memory is/are specified via one or multiple scsiif_request_segment 102 * descriptors each specifying a memory page via a grant_ref_t, a offset into 103 * the page and the length of the area in that page. All scsiif_request_segment 104 * areas concatenated form the resulting data buffer used by the operation. 105 * If the number of scsiif_request_segment areas is not too large (less than 106 * or equal VSCSIIF_SG_TABLESIZE) the areas can be specified directly in the 107 * seg[] array and the number of valid scsiif_request_segment elements is to be 108 * set in nr_segments. 109 * 110 * If "feature-sg-grant" in the Xenstore is set it is possible to specify more 111 * than VSCSIIF_SG_TABLESIZE scsiif_request_segment elements via indirection. 112 * The maximum number of allowed scsiif_request_segment elements is the value 113 * of the "feature-sg-grant" entry from Xenstore. When using indirection the 114 * seg[] array doesn't contain specifications of the data buffers, but 115 * references to scsiif_request_segment arrays, which in turn reference the 116 * data buffers. While nr_segments holds the number of populated seg[] entries 117 * (plus the set VSCSIIF_SG_GRANT bit), the number of scsiif_request_segment 118 * elements referencing the target data buffers is calculated from the lengths 119 * of the seg[] elements (the sum of all valid seg[].length divided by the 120 * size of one scsiif_request_segment structure). 121 */ 122 #define VSCSIIF_ACT_SCSI_CDB 1 123 124 /* 125 * Request abort of a running operation for the specified target given by 126 * channel, id, lun and the operation's rqid in ref_rqid. 127 */ 128 #define VSCSIIF_ACT_SCSI_ABORT 2 129 130 /* 131 * Request a device reset of the specified target (channel and id). 132 */ 133 #define VSCSIIF_ACT_SCSI_RESET 3 134 135 /* 136 * Preset scatter/gather elements for a following request. Deprecated. 137 * Keeping the define only to avoid usage of the value "4" for other actions. 138 */ 139 #define VSCSIIF_ACT_SCSI_SG_PRESET 4 140 141 /* 142 * Maximum scatter/gather segments per request. 143 * 144 * Considering balance between allocating at least 16 "vscsiif_request" 145 * structures on one page (4096 bytes) and the number of scatter/gather 146 * elements needed, we decided to use 26 as a magic number. 147 * 148 * If "feature-sg-grant" is set, more scatter/gather elements can be specified 149 * by placing them in one or more (up to VSCSIIF_SG_TABLESIZE) granted pages. 150 * In this case the vscsiif_request seg elements don't contain references to 151 * the user data, but to the SG elements referencing the user data. 152 */ 153 #define VSCSIIF_SG_TABLESIZE 26 154 155 /* 156 * based on Linux kernel 2.6.18, still valid 157 * Changing these values requires support of multiple protocols via the rings 158 * as "old clients" will blindly use these values and the resulting structure 159 * sizes. 160 */ 161 #define VSCSIIF_MAX_COMMAND_SIZE 16 162 #define VSCSIIF_SENSE_BUFFERSIZE 96 163 164 struct scsiif_request_segment { 165 grant_ref_t gref; 166 uint16_t offset; 167 uint16_t length; 168 }; 169 170 #define VSCSIIF_SG_PER_PAGE (PAGE_SIZE / sizeof(struct scsiif_request_segment)) 171 172 /* Size of one request is 252 bytes */ 173 struct vscsiif_request { 174 uint16_t rqid; /* private guest value, echoed in resp */ 175 uint8_t act; /* command between backend and frontend */ 176 uint8_t cmd_len; /* valid CDB bytes */ 177 178 uint8_t cmnd[VSCSIIF_MAX_COMMAND_SIZE]; /* the CDB */ 179 uint16_t timeout_per_command; /* deprecated */ 180 uint16_t channel, id, lun; /* (virtual) device specification */ 181 uint16_t ref_rqid; /* command abort reference */ 182 uint8_t sc_data_direction; /* for DMA_TO_DEVICE(1) 183 DMA_FROM_DEVICE(2) 184 DMA_NONE(3) requests */ 185 uint8_t nr_segments; /* Number of pieces of scatter-gather */ 186 /* 187 * flag in nr_segments: SG elements via grant page 188 * 189 * If VSCSIIF_SG_GRANT is set, the low 7 bits of nr_segments specify the number 190 * of grant pages containing SG elements. Usable if "feature-sg-grant" set. 191 */ 192 #define VSCSIIF_SG_GRANT 0x80 193 194 struct scsiif_request_segment seg[VSCSIIF_SG_TABLESIZE]; 195 uint32_t reserved[3]; 196 }; 197 198 /* Size of one response is 252 bytes */ 199 struct vscsiif_response { 200 uint16_t rqid; /* identifies request */ 201 uint8_t padding; 202 uint8_t sense_len; 203 uint8_t sense_buffer[VSCSIIF_SENSE_BUFFERSIZE]; 204 int32_t rslt; 205 uint32_t residual_len; /* request bufflen - 206 return the value from physical device */ 207 uint32_t reserved[36]; 208 }; 209 210 DEFINE_RING_TYPES(vscsiif, struct vscsiif_request, struct vscsiif_response); 211 212 #endif /*__XEN__PUBLIC_IO_SCSI_H__*/ 213