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.60014054ac780582:0").
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/*
91 * Xenstore format in practice
92 * ===========================
93 *
94 * The backend driver uses a single_host:many_devices notation to manage domU
95 * devices. Everything is stored in /local/domain/<backend_domid>/backend/vscsi/.
96 * The xenstore layout looks like this (dom0 is assumed to be the backend_domid):
97 *
98 * <domid>/<vhost>/feature-host = "0"
99 * <domid>/<vhost>/frontend = "/local/domain/<domid>/device/vscsi/0"
100 * <domid>/<vhost>/frontend-id = "<domid>"
101 * <domid>/<vhost>/online = "1"
102 * <domid>/<vhost>/state = "4"
103 * <domid>/<vhost>/vscsi-devs/dev-0/p-dev = "8:0:2:1" or "naa.wwn:lun"
104 * <domid>/<vhost>/vscsi-devs/dev-0/state = "4"
105 * <domid>/<vhost>/vscsi-devs/dev-0/v-dev = "0:0:0:0"
106 * <domid>/<vhost>/vscsi-devs/dev-1/p-dev = "8:0:2:2"
107 * <domid>/<vhost>/vscsi-devs/dev-1/state = "4"
108 * <domid>/<vhost>/vscsi-devs/dev-1/v-dev = "0:0:1:0"
109 *
110 * The frontend driver maintains its state in
111 * /local/domain/<domid>/device/vscsi/.
112 *
113 * <vhost>/backend = "/local/domain/0/backend/vscsi/<domid>/<vhost>"
114 * <vhost>/backend-id = "0"
115 * <vhost>/event-channel = "20"
116 * <vhost>/ring-ref = "43"
117 * <vhost>/state = "4"
118 * <vhost>/vscsi-devs/dev-0/state = "4"
119 * <vhost>/vscsi-devs/dev-1/state = "4"
120 *
121 * In addition to the entries for backend and frontend these flags are stored
122 * for the toolstack:
123 *
124 * <domid>/<vhost>/vscsi-devs/dev-1/p-devname = "/dev/$device"
125 * <domid>/<vhost>/libxl_ctrl_index = "0"
126 *
127 *
128 * Backend/frontend protocol
129 * =========================
130 *
131 * To create a vhost along with a device:
132 * <domid>/<vhost>/feature-host = "0"
133 * <domid>/<vhost>/frontend = "/local/domain/<domid>/device/vscsi/0"
134 * <domid>/<vhost>/frontend-id = "<domid>"
135 * <domid>/<vhost>/online = "1"
136 * <domid>/<vhost>/state = "1"
137 * <domid>/<vhost>/vscsi-devs/dev-0/p-dev = "8:0:2:1"
138 * <domid>/<vhost>/vscsi-devs/dev-0/state = "1"
139 * <domid>/<vhost>/vscsi-devs/dev-0/v-dev = "0:0:0:0"
140 * Wait for <domid>/<vhost>/state + <domid>/<vhost>/vscsi-devs/dev-0/state become 4
141 *
142 * To add another device to a vhost:
143 * <domid>/<vhost>/state = "7"
144 * <domid>/<vhost>/vscsi-devs/dev-1/p-dev = "8:0:2:2"
145 * <domid>/<vhost>/vscsi-devs/dev-1/state = "1"
146 * <domid>/<vhost>/vscsi-devs/dev-1/v-dev = "0:0:1:0"
147 * Wait for <domid>/<vhost>/state + <domid>/<vhost>/vscsi-devs/dev-1/state become 4
148 *
149 * To remove a device from a vhost:
150 * <domid>/<vhost>/state = "7"
151 * <domid>/<vhost>/vscsi-devs/dev-1/state = "5"
152 * Wait for <domid>/<vhost>/state to become 4
153 * Wait for <domid>/<vhost>/vscsi-devs/dev-1/state become 6
154 * Remove <domid>/<vhost>/vscsi-devs/dev-1/{state,p-dev,v-dev,p-devname}
155 * Remove <domid>/<vhost>/vscsi-devs/dev-1/
156 *
157 */
158
159/* Requests from the frontend to the backend */
160
161/*
162 * Request a SCSI operation specified via a CDB in vscsiif_request.cmnd.
163 * The target is specified via channel, id and lun.
164 *
165 * The operation to be performed is specified via a CDB in cmnd[], the length
166 * of the CDB is in cmd_len. sc_data_direction specifies the direction of data
167 * (to the device, from the device, or none at all).
168 *
169 * If data is to be transferred to or from the device the buffer(s) in the
170 * guest memory is/are specified via one or multiple scsiif_request_segment
171 * descriptors each specifying a memory page via a grant_ref_t, a offset into
172 * the page and the length of the area in that page. All scsiif_request_segment
173 * areas concatenated form the resulting data buffer used by the operation.
174 * If the number of scsiif_request_segment areas is not too large (less than
175 * or equal VSCSIIF_SG_TABLESIZE) the areas can be specified directly in the
176 * seg[] array and the number of valid scsiif_request_segment elements is to be
177 * set in nr_segments.
178 *
179 * If "feature-sg-grant" in the Xenstore is set it is possible to specify more
180 * than VSCSIIF_SG_TABLESIZE scsiif_request_segment elements via indirection.
181 * The maximum number of allowed scsiif_request_segment elements is the value
182 * of the "feature-sg-grant" entry from Xenstore. When using indirection the
183 * seg[] array doesn't contain specifications of the data buffers, but
184 * references to scsiif_request_segment arrays, which in turn reference the
185 * data buffers. While nr_segments holds the number of populated seg[] entries
186 * (plus the set VSCSIIF_SG_GRANT bit), the number of scsiif_request_segment
187 * elements referencing the target data buffers is calculated from the lengths
188 * of the seg[] elements (the sum of all valid seg[].length divided by the
189 * size of one scsiif_request_segment structure). The frontend may use a mix of
190 * direct and indirect requests.
191 */
192#define VSCSIIF_ACT_SCSI_CDB 1
193
194/*
195 * Request abort of a running operation for the specified target given by
196 * channel, id, lun and the operation's rqid in ref_rqid.
197 */
198#define VSCSIIF_ACT_SCSI_ABORT 2
199
200/*
201 * Request a device reset of the specified target (channel and id).
202 */
203#define VSCSIIF_ACT_SCSI_RESET 3
204
205/*
206 * Preset scatter/gather elements for a following request. Deprecated.
207 * Keeping the define only to avoid usage of the value "4" for other actions.
208 */
209#define VSCSIIF_ACT_SCSI_SG_PRESET 4
210
211/*
212 * Maximum scatter/gather segments per request.
213 *
214 * Considering balance between allocating at least 16 "vscsiif_request"
215 * structures on one page (4096 bytes) and the number of scatter/gather
216 * elements needed, we decided to use 26 as a magic number.
217 *
218 * If "feature-sg-grant" is set, more scatter/gather elements can be specified
219 * by placing them in one or more (up to VSCSIIF_SG_TABLESIZE) granted pages.
220 * In this case the vscsiif_request seg elements don't contain references to
221 * the user data, but to the SG elements referencing the user data.
222 */
223#define VSCSIIF_SG_TABLESIZE 26
224
225/*
226 * based on Linux kernel 2.6.18, still valid
227 *
228 * Changing these values requires support of multiple protocols via the rings
229 * as "old clients" will blindly use these values and the resulting structure
230 * sizes.
231 */
232#define VSCSIIF_MAX_COMMAND_SIZE 16
233#define VSCSIIF_SENSE_BUFFERSIZE 96
234#define VSCSIIF_PAGE_SIZE 4096
235
236struct scsiif_request_segment {
237 grant_ref_t gref;
238 uint16_t offset;
239 uint16_t length;
240};
241
242#define VSCSIIF_SG_PER_PAGE (VSCSIIF_PAGE_SIZE / \
243 sizeof(struct scsiif_request_segment))
244
245/* Size of one request is 252 bytes */
246struct vscsiif_request {
247 uint16_t rqid; /* private guest value, echoed in resp */
248 uint8_t act; /* command between backend and frontend */
249 uint8_t cmd_len; /* valid CDB bytes */
250
251 uint8_t cmnd[VSCSIIF_MAX_COMMAND_SIZE]; /* the CDB */
252 uint16_t timeout_per_command; /* deprecated */
253 uint16_t channel, id, lun; /* (virtual) device specification */
254 uint16_t ref_rqid; /* command abort reference */
255 uint8_t sc_data_direction; /* for DMA_TO_DEVICE(1)
256 DMA_FROM_DEVICE(2)
257 DMA_NONE(3) requests */
258 uint8_t nr_segments; /* Number of pieces of scatter-gather */
259/*
260 * flag in nr_segments: SG elements via grant page
261 *
262 * If VSCSIIF_SG_GRANT is set, the low 7 bits of nr_segments specify the number
263 * of grant pages containing SG elements. Usable if "feature-sg-grant" set.
264 */
265#define VSCSIIF_SG_GRANT 0x80
266
267 struct scsiif_request_segment seg[VSCSIIF_SG_TABLESIZE];
268 uint32_t reserved[3];
269};
270
271/* Size of one response is 252 bytes */
272struct vscsiif_response {
273 uint16_t rqid; /* identifies request */
274 uint8_t padding;
275 uint8_t sense_len;
276 uint8_t sense_buffer[VSCSIIF_SENSE_BUFFERSIZE];
277 int32_t rslt;
278 uint32_t residual_len; /* request bufflen -
279 return the value from physical device */
280 uint32_t reserved[36];
281};
282
283/* SCSI I/O status from vscsiif_response->rslt */
284#define XEN_VSCSIIF_RSLT_STATUS(x) ((x) & 0x00ff)
285
286/* Host I/O status from vscsiif_response->rslt */
287#define XEN_VSCSIIF_RSLT_HOST(x) (((x) & 0x00ff0000) >> 16)
288#define XEN_VSCSIIF_RSLT_HOST_OK 0
289/* Couldn't connect before timeout */
290#define XEN_VSCSIIF_RSLT_HOST_NO_CONNECT 1
291/* Bus busy through timeout */
292#define XEN_VSCSIIF_RSLT_HOST_BUS_BUSY 2
293/* Timed out for other reason */
294#define XEN_VSCSIIF_RSLT_HOST_TIME_OUT 3
295/* Bad target */
296#define XEN_VSCSIIF_RSLT_HOST_BAD_TARGET 4
297/* Abort for some other reason */
298#define XEN_VSCSIIF_RSLT_HOST_ABORT 5
299/* Parity error */
300#define XEN_VSCSIIF_RSLT_HOST_PARITY 6
301/* Internal error */
302#define XEN_VSCSIIF_RSLT_HOST_ERROR 7
303/* Reset by somebody */
304#define XEN_VSCSIIF_RSLT_HOST_RESET 8
305/* Unexpected interrupt */
306#define XEN_VSCSIIF_RSLT_HOST_BAD_INTR 9
307/* Force command past mid-layer */
308#define XEN_VSCSIIF_RSLT_HOST_PASSTHROUGH 10
309/* Retry requested */
310#define XEN_VSCSIIF_RSLT_HOST_SOFT_ERROR 11
311/* Hidden retry requested */
312#define XEN_VSCSIIF_RSLT_HOST_IMM_RETRY 12
313/* Requeue command requested */
314#define XEN_VSCSIIF_RSLT_HOST_REQUEUE 13
315/* Transport error disrupted I/O */
316#define XEN_VSCSIIF_RSLT_HOST_TRANSPORT_DISRUPTED 14
317/* Transport class fastfailed */
318#define XEN_VSCSIIF_RSLT_HOST_TRANSPORT_FAILFAST 15
319/* Permanent target failure */
320#define XEN_VSCSIIF_RSLT_HOST_TARGET_FAILURE 16
321/* Permanent nexus failure on path */
322#define XEN_VSCSIIF_RSLT_HOST_NEXUS_FAILURE 17
323/* Space allocation on device failed */
324#define XEN_VSCSIIF_RSLT_HOST_ALLOC_FAILURE 18
325/* Medium error */
326#define XEN_VSCSIIF_RSLT_HOST_MEDIUM_ERROR 19
327/* Transport marginal errors */
328#define XEN_VSCSIIF_RSLT_HOST_TRANSPORT_MARGINAL 20
329
330/* Result values of reset operations */
331#define XEN_VSCSIIF_RSLT_RESET_SUCCESS 0x2002
332#define XEN_VSCSIIF_RSLT_RESET_FAILED 0x2003
333
334DEFINE_RING_TYPES(vscsiif, struct vscsiif_request, struct vscsiif_response);
335
336
337#endif /*__XEN__PUBLIC_IO_SCSI_H__*/
338

source code of linux/include/xen/interface/io/vscsiif.h