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1/******************************************************************************
2 * blkif.h
3 *
4 * Unified block-device I/O interface for Xen guest OSes.
5 *
6 * Copyright (c) 2003-2004, Keir Fraser
7 */
8
9#ifndef __XEN_PUBLIC_IO_BLKIF_H__
10#define __XEN_PUBLIC_IO_BLKIF_H__
11
12#include "ring.h"
13#include "../grant_table.h"
14
15/*
16 * Front->back notifications: When enqueuing a new request, sending a
17 * notification can be made conditional on req_event (i.e., the generic
18 * hold-off mechanism provided by the ring macros). Backends must set
19 * req_event appropriately (e.g., using RING_FINAL_CHECK_FOR_REQUESTS()).
20 *
21 * Back->front notifications: When enqueuing a new response, sending a
22 * notification can be made conditional on rsp_event (i.e., the generic
23 * hold-off mechanism provided by the ring macros). Frontends must set
24 * rsp_event appropriately (e.g., using RING_FINAL_CHECK_FOR_RESPONSES()).
25 */
26
27typedef uint16_t blkif_vdev_t;
28typedef uint64_t blkif_sector_t;
29
30/*
31 * REQUEST CODES.
32 */
33#define BLKIF_OP_READ 0
34#define BLKIF_OP_WRITE 1
35/*
36 * Recognised only if "feature-barrier" is present in backend xenbus info.
37 * The "feature_barrier" node contains a boolean indicating whether barrier
38 * requests are likely to succeed or fail. Either way, a barrier request
39 * may fail at any time with BLKIF_RSP_EOPNOTSUPP if it is unsupported by
40 * the underlying block-device hardware. The boolean simply indicates whether
41 * or not it is worthwhile for the frontend to attempt barrier requests.
42 * If a backend does not recognise BLKIF_OP_WRITE_BARRIER, it should *not*
43 * create the "feature-barrier" node!
44 */
45#define BLKIF_OP_WRITE_BARRIER 2
46
47/*
48 * Recognised if "feature-flush-cache" is present in backend xenbus
49 * info. A flush will ask the underlying storage hardware to flush its
50 * non-volatile caches as appropriate. The "feature-flush-cache" node
51 * contains a boolean indicating whether flush requests are likely to
52 * succeed or fail. Either way, a flush request may fail at any time
53 * with BLKIF_RSP_EOPNOTSUPP if it is unsupported by the underlying
54 * block-device hardware. The boolean simply indicates whether or not it
55 * is worthwhile for the frontend to attempt flushes. If a backend does
56 * not recognise BLKIF_OP_WRITE_FLUSH_CACHE, it should *not* create the
57 * "feature-flush-cache" node!
58 */
59#define BLKIF_OP_FLUSH_DISKCACHE 3
60/*
61 * Maximum scatter/gather segments per request.
62 * This is carefully chosen so that sizeof(struct blkif_ring) <= PAGE_SIZE.
63 * NB. This could be 12 if the ring indexes weren't stored in the same page.
64 */
65#define BLKIF_MAX_SEGMENTS_PER_REQUEST 11
66
67struct blkif_request_rw {
68 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
69 struct blkif_request_segment {
70 grant_ref_t gref; /* reference to I/O buffer frame */
71 /* @first_sect: first sector in frame to transfer (inclusive). */
72 /* @last_sect: last sector in frame to transfer (inclusive). */
73 uint8_t first_sect, last_sect;
74 } seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
75};
76
77struct blkif_request {
78 uint8_t operation; /* BLKIF_OP_??? */
79 uint8_t nr_segments; /* number of segments */
80 blkif_vdev_t handle; /* only for read/write requests */
81 uint64_t id; /* private guest value, echoed in resp */
82 union {
83 struct blkif_request_rw rw;
84 } u;
85};
86
87struct blkif_response {
88 uint64_t id; /* copied from request */
89 uint8_t operation; /* copied from request */
90 int16_t status; /* BLKIF_RSP_??? */
91};
92
93/*
94 * STATUS RETURN CODES.
95 */
96 /* Operation not supported (only happens on barrier writes). */
97#define BLKIF_RSP_EOPNOTSUPP -2
98 /* Operation failed for some unspecified reason (-EIO). */
99#define BLKIF_RSP_ERROR -1
100 /* Operation completed successfully. */
101#define BLKIF_RSP_OKAY 0
102
103/*
104 * Generate blkif ring structures and types.
105 */
106
107DEFINE_RING_TYPES(blkif, struct blkif_request, struct blkif_response);
108
109#define VDISK_CDROM 0x1
110#define VDISK_REMOVABLE 0x2
111#define VDISK_READONLY 0x4
112
113/* Xen-defined major numbers for virtual disks, they look strangely
114 * familiar */
115#define XEN_IDE0_MAJOR 3
116#define XEN_IDE1_MAJOR 22
117#define XEN_SCSI_DISK0_MAJOR 8
118#define XEN_SCSI_DISK1_MAJOR 65
119#define XEN_SCSI_DISK2_MAJOR 66
120#define XEN_SCSI_DISK3_MAJOR 67
121#define XEN_SCSI_DISK4_MAJOR 68
122#define XEN_SCSI_DISK5_MAJOR 69
123#define XEN_SCSI_DISK6_MAJOR 70
124#define XEN_SCSI_DISK7_MAJOR 71
125#define XEN_SCSI_DISK8_MAJOR 128
126#define XEN_SCSI_DISK9_MAJOR 129
127#define XEN_SCSI_DISK10_MAJOR 130
128#define XEN_SCSI_DISK11_MAJOR 131
129#define XEN_SCSI_DISK12_MAJOR 132
130#define XEN_SCSI_DISK13_MAJOR 133
131#define XEN_SCSI_DISK14_MAJOR 134
132#define XEN_SCSI_DISK15_MAJOR 135
133
134#endif /* __XEN_PUBLIC_IO_BLKIF_H__ */
1/******************************************************************************
2 * blkif.h
3 *
4 * Unified block-device I/O interface for Xen guest OSes.
5 *
6 * Copyright (c) 2003-2004, Keir Fraser
7 */
8
9#ifndef __XEN_PUBLIC_IO_BLKIF_H__
10#define __XEN_PUBLIC_IO_BLKIF_H__
11
12#include "ring.h"
13#include "../grant_table.h"
14
15/*
16 * Front->back notifications: When enqueuing a new request, sending a
17 * notification can be made conditional on req_event (i.e., the generic
18 * hold-off mechanism provided by the ring macros). Backends must set
19 * req_event appropriately (e.g., using RING_FINAL_CHECK_FOR_REQUESTS()).
20 *
21 * Back->front notifications: When enqueuing a new response, sending a
22 * notification can be made conditional on rsp_event (i.e., the generic
23 * hold-off mechanism provided by the ring macros). Frontends must set
24 * rsp_event appropriately (e.g., using RING_FINAL_CHECK_FOR_RESPONSES()).
25 */
26
27typedef uint16_t blkif_vdev_t;
28typedef uint64_t blkif_sector_t;
29
30/*
31 * REQUEST CODES.
32 */
33#define BLKIF_OP_READ 0
34#define BLKIF_OP_WRITE 1
35/*
36 * Recognised only if "feature-barrier" is present in backend xenbus info.
37 * The "feature_barrier" node contains a boolean indicating whether barrier
38 * requests are likely to succeed or fail. Either way, a barrier request
39 * may fail at any time with BLKIF_RSP_EOPNOTSUPP if it is unsupported by
40 * the underlying block-device hardware. The boolean simply indicates whether
41 * or not it is worthwhile for the frontend to attempt barrier requests.
42 * If a backend does not recognise BLKIF_OP_WRITE_BARRIER, it should *not*
43 * create the "feature-barrier" node!
44 */
45#define BLKIF_OP_WRITE_BARRIER 2
46
47/*
48 * Recognised if "feature-flush-cache" is present in backend xenbus
49 * info. A flush will ask the underlying storage hardware to flush its
50 * non-volatile caches as appropriate. The "feature-flush-cache" node
51 * contains a boolean indicating whether flush requests are likely to
52 * succeed or fail. Either way, a flush request may fail at any time
53 * with BLKIF_RSP_EOPNOTSUPP if it is unsupported by the underlying
54 * block-device hardware. The boolean simply indicates whether or not it
55 * is worthwhile for the frontend to attempt flushes. If a backend does
56 * not recognise BLKIF_OP_WRITE_FLUSH_CACHE, it should *not* create the
57 * "feature-flush-cache" node!
58 */
59#define BLKIF_OP_FLUSH_DISKCACHE 3
60
61/*
62 * Recognised only if "feature-discard" is present in backend xenbus info.
63 * The "feature-discard" node contains a boolean indicating whether trim
64 * (ATA) or unmap (SCSI) - conviently called discard requests are likely
65 * to succeed or fail. Either way, a discard request
66 * may fail at any time with BLKIF_RSP_EOPNOTSUPP if it is unsupported by
67 * the underlying block-device hardware. The boolean simply indicates whether
68 * or not it is worthwhile for the frontend to attempt discard requests.
69 * If a backend does not recognise BLKIF_OP_DISCARD, it should *not*
70 * create the "feature-discard" node!
71 *
72 * Discard operation is a request for the underlying block device to mark
73 * extents to be erased. However, discard does not guarantee that the blocks
74 * will be erased from the device - it is just a hint to the device
75 * controller that these blocks are no longer in use. What the device
76 * controller does with that information is left to the controller.
77 * Discard operations are passed with sector_number as the
78 * sector index to begin discard operations at and nr_sectors as the number of
79 * sectors to be discarded. The specified sectors should be discarded if the
80 * underlying block device supports trim (ATA) or unmap (SCSI) operations,
81 * or a BLKIF_RSP_EOPNOTSUPP should be returned.
82 * More information about trim/unmap operations at:
83 * http://t13.org/Documents/UploadedDocuments/docs2008/
84 * e07154r6-Data_Set_Management_Proposal_for_ATA-ACS2.doc
85 * http://www.seagate.com/staticfiles/support/disc/manuals/
86 * Interface%20manuals/100293068c.pdf
87 * The backend can optionally provide three extra XenBus attributes to
88 * further optimize the discard functionality:
89 * 'discard-aligment' - Devices that support discard functionality may
90 * internally allocate space in units that are bigger than the exported
91 * logical block size. The discard-alignment parameter indicates how many bytes
92 * the beginning of the partition is offset from the internal allocation unit's
93 * natural alignment.
94 * 'discard-granularity' - Devices that support discard functionality may
95 * internally allocate space using units that are bigger than the logical block
96 * size. The discard-granularity parameter indicates the size of the internal
97 * allocation unit in bytes if reported by the device. Otherwise the
98 * discard-granularity will be set to match the device's physical block size.
99 * 'discard-secure' - All copies of the discarded sectors (potentially created
100 * by garbage collection) must also be erased. To use this feature, the flag
101 * BLKIF_DISCARD_SECURE must be set in the blkif_request_trim.
102 */
103#define BLKIF_OP_DISCARD 5
104
105/*
106 * Maximum scatter/gather segments per request.
107 * This is carefully chosen so that sizeof(struct blkif_ring) <= PAGE_SIZE.
108 * NB. This could be 12 if the ring indexes weren't stored in the same page.
109 */
110#define BLKIF_MAX_SEGMENTS_PER_REQUEST 11
111
112struct blkif_request_rw {
113 uint8_t nr_segments; /* number of segments */
114 blkif_vdev_t handle; /* only for read/write requests */
115#ifdef CONFIG_X86_64
116 uint32_t _pad1; /* offsetof(blkif_request,u.rw.id) == 8 */
117#endif
118 uint64_t id; /* private guest value, echoed in resp */
119 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
120 struct blkif_request_segment {
121 grant_ref_t gref; /* reference to I/O buffer frame */
122 /* @first_sect: first sector in frame to transfer (inclusive). */
123 /* @last_sect: last sector in frame to transfer (inclusive). */
124 uint8_t first_sect, last_sect;
125 } seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
126} __attribute__((__packed__));
127
128struct blkif_request_discard {
129 uint8_t flag; /* BLKIF_DISCARD_SECURE or zero. */
130#define BLKIF_DISCARD_SECURE (1<<0) /* ignored if discard-secure=0 */
131 blkif_vdev_t _pad1; /* only for read/write requests */
132#ifdef CONFIG_X86_64
133 uint32_t _pad2; /* offsetof(blkif_req..,u.discard.id)==8*/
134#endif
135 uint64_t id; /* private guest value, echoed in resp */
136 blkif_sector_t sector_number;
137 uint64_t nr_sectors;
138 uint8_t _pad3;
139} __attribute__((__packed__));
140
141struct blkif_request {
142 uint8_t operation; /* BLKIF_OP_??? */
143 union {
144 struct blkif_request_rw rw;
145 struct blkif_request_discard discard;
146 } u;
147} __attribute__((__packed__));
148
149struct blkif_response {
150 uint64_t id; /* copied from request */
151 uint8_t operation; /* copied from request */
152 int16_t status; /* BLKIF_RSP_??? */
153};
154
155/*
156 * STATUS RETURN CODES.
157 */
158 /* Operation not supported (only happens on barrier writes). */
159#define BLKIF_RSP_EOPNOTSUPP -2
160 /* Operation failed for some unspecified reason (-EIO). */
161#define BLKIF_RSP_ERROR -1
162 /* Operation completed successfully. */
163#define BLKIF_RSP_OKAY 0
164
165/*
166 * Generate blkif ring structures and types.
167 */
168
169DEFINE_RING_TYPES(blkif, struct blkif_request, struct blkif_response);
170
171#define VDISK_CDROM 0x1
172#define VDISK_REMOVABLE 0x2
173#define VDISK_READONLY 0x4
174
175/* Xen-defined major numbers for virtual disks, they look strangely
176 * familiar */
177#define XEN_IDE0_MAJOR 3
178#define XEN_IDE1_MAJOR 22
179#define XEN_SCSI_DISK0_MAJOR 8
180#define XEN_SCSI_DISK1_MAJOR 65
181#define XEN_SCSI_DISK2_MAJOR 66
182#define XEN_SCSI_DISK3_MAJOR 67
183#define XEN_SCSI_DISK4_MAJOR 68
184#define XEN_SCSI_DISK5_MAJOR 69
185#define XEN_SCSI_DISK6_MAJOR 70
186#define XEN_SCSI_DISK7_MAJOR 71
187#define XEN_SCSI_DISK8_MAJOR 128
188#define XEN_SCSI_DISK9_MAJOR 129
189#define XEN_SCSI_DISK10_MAJOR 130
190#define XEN_SCSI_DISK11_MAJOR 131
191#define XEN_SCSI_DISK12_MAJOR 132
192#define XEN_SCSI_DISK13_MAJOR 133
193#define XEN_SCSI_DISK14_MAJOR 134
194#define XEN_SCSI_DISK15_MAJOR 135
195
196#endif /* __XEN_PUBLIC_IO_BLKIF_H__ */