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
181 struct 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 */
190 struct 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 */
216 struct 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
227 DEFINE_RING_TYPES(vscsiif, struct vscsiif_request, struct vscsiif_response);
228
229 #endif /*__XEN__PUBLIC_IO_SCSI_H__*/