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1.1 root 1: /******************************************************************************
2: * blkif.h
3: *
4: * Unified block-device I/O interface for Xen guest OSes.
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) 2003-2004, Keir Fraser
25: */
26:
27: #ifndef __XEN_PUBLIC_IO_BLKIF_H__
28: #define __XEN_PUBLIC_IO_BLKIF_H__
29:
30: #include "ring.h"
31: #include "../grant_table.h"
32:
33: /*
34: * Front->back notifications: When enqueuing a new request, sending a
35: * notification can be made conditional on req_event (i.e., the generic
36: * hold-off mechanism provided by the ring macros). Backends must set
37: * req_event appropriately (e.g., using RING_FINAL_CHECK_FOR_REQUESTS()).
38: *
39: * Back->front notifications: When enqueuing a new response, sending a
40: * notification can be made conditional on rsp_event (i.e., the generic
41: * hold-off mechanism provided by the ring macros). Frontends must set
42: * rsp_event appropriately (e.g., using RING_FINAL_CHECK_FOR_RESPONSES()).
43: */
44:
45: #ifndef blkif_vdev_t
46: #define blkif_vdev_t uint16_t
47: #endif
48: #define blkif_sector_t uint64_t
49:
50: /*
51: * REQUEST CODES.
52: */
53: #define BLKIF_OP_READ 0
54: #define BLKIF_OP_WRITE 1
55: /*
56: * Recognised only if "feature-barrier" is present in backend xenbus info.
57: * The "feature-barrier" node contains a boolean indicating whether barrier
58: * requests are likely to succeed or fail. Either way, a barrier request
59: * may fail at any time with BLKIF_RSP_EOPNOTSUPP if it is unsupported by
60: * the underlying block-device hardware. The boolean simply indicates whether
61: * or not it is worthwhile for the frontend to attempt barrier requests.
62: * If a backend does not recognise BLKIF_OP_WRITE_BARRIER, it should *not*
63: * create the "feature-barrier" node!
64: */
65: #define BLKIF_OP_WRITE_BARRIER 2
66: /*
67: * Recognised if "feature-flush-cache" is present in backend xenbus
68: * info. A flush will ask the underlying storage hardware to flush its
69: * non-volatile caches as appropriate. The "feature-flush-cache" node
70: * contains a boolean indicating whether flush requests are likely to
71: * succeed or fail. Either way, a flush request may fail at any time
72: * with BLKIF_RSP_EOPNOTSUPP if it is unsupported by the underlying
73: * block-device hardware. The boolean simply indicates whether or not it
74: * is worthwhile for the frontend to attempt flushes. If a backend does
75: * not recognise BLKIF_OP_WRITE_FLUSH_CACHE, it should *not* create the
76: * "feature-flush-cache" node!
77: */
78: #define BLKIF_OP_FLUSH_DISKCACHE 3
79:
80: /*
81: * Maximum scatter/gather segments per request.
82: * This is carefully chosen so that sizeof(blkif_ring_t) <= PAGE_SIZE.
83: * NB. This could be 12 if the ring indexes weren't stored in the same page.
84: */
85: #define BLKIF_MAX_SEGMENTS_PER_REQUEST 11
86:
87: struct blkif_request_segment {
88: grant_ref_t gref; /* reference to I/O buffer frame */
89: /* @first_sect: first sector in frame to transfer (inclusive). */
90: /* @last_sect: last sector in frame to transfer (inclusive). */
91: uint8_t first_sect, last_sect;
92: };
93:
94: struct blkif_request {
95: uint8_t operation; /* BLKIF_OP_??? */
96: uint8_t nr_segments; /* number of segments */
97: blkif_vdev_t handle; /* only for read/write requests */
98: uint64_t id; /* private guest value, echoed in resp */
99: blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
100: struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
101: };
102: typedef struct blkif_request blkif_request_t;
103:
104: struct blkif_response {
105: uint64_t id; /* copied from request */
106: uint8_t operation; /* copied from request */
107: int16_t status; /* BLKIF_RSP_??? */
108: };
109: typedef struct blkif_response blkif_response_t;
110:
111: /*
112: * STATUS RETURN CODES.
113: */
114: /* Operation not supported (only happens on barrier writes). */
115: #define BLKIF_RSP_EOPNOTSUPP -2
116: /* Operation failed for some unspecified reason (-EIO). */
117: #define BLKIF_RSP_ERROR -1
118: /* Operation completed successfully. */
119: #define BLKIF_RSP_OKAY 0
120:
121: /*
122: * Generate blkif ring structures and types.
123: */
124:
125: DEFINE_RING_TYPES(blkif, struct blkif_request, struct blkif_response);
126:
127: #define VDISK_CDROM 0x1
128: #define VDISK_REMOVABLE 0x2
129: #define VDISK_READONLY 0x4
130:
131: #endif /* __XEN_PUBLIC_IO_BLKIF_H__ */
132:
133: /*
134: * Local variables:
135: * mode: C
136: * c-set-style: "BSD"
137: * c-basic-offset: 4
138: * tab-width: 4
139: * indent-tabs-mode: nil
140: * End:
141: */
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