1 /*
2 * Permission is hereby granted, free of charge, to any person obtaining a copy
3 * of this software and associated documentation files (the "Software"), to
4 * deal in the Software without restriction, including without limitation the
5 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
6 * sell copies of the Software, and to permit persons to whom the Software is
7 * furnished to do so, subject to the following conditions:
8 *
9 * The above copyright notice and this permission notice shall be included in
10 * all copies or substantial portions of the Software.
11 *
12 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
13 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
14 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
15 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
16 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
17 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
18 * DEALINGS IN THE SOFTWARE.
19 */
20
21 #ifndef __XEN_BLKIF_H__
22 #define __XEN_BLKIF_H__
23
24 #include <contrib/xen/io/ring.h>
25 #include <contrib/xen/io/blkif.h>
26 #include <contrib/xen/io/protocols.h>
27
28 /* Not a real protocol. Used to generate ring structs which contain
29 * the elements common to all protocols only. This way we get a
30 * compiler-checkable way to use common struct elements, so we can
31 * avoid using switch(protocol) in a number of places. */
32 struct blkif_common_request {
33 char dummy;
34 };
35 struct blkif_common_response {
36 char dummy;
37 };
38
39 /* i386 protocol version */
40 #pragma pack(push, 4)
41 struct blkif_x86_32_request {
42 uint8_t operation; /* BLKIF_OP_??? */
43 uint8_t nr_segments; /* number of segments */
44 blkif_vdev_t handle; /* only for read/write requests */
45 uint64_t id; /* private guest value, echoed in resp */
46 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
47 struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
48 };
49 struct blkif_x86_32_response {
50 uint64_t id; /* copied from request */
51 uint8_t operation; /* copied from request */
52 int16_t status; /* BLKIF_RSP_??? */
53 };
54 typedef struct blkif_x86_32_request blkif_x86_32_request_t;
55 typedef struct blkif_x86_32_response blkif_x86_32_response_t;
56 #pragma pack(pop)
57
58 /* x86_64 protocol version */
59 struct blkif_x86_64_request {
60 uint8_t operation; /* BLKIF_OP_??? */
61 uint8_t nr_segments; /* number of segments */
62 blkif_vdev_t handle; /* only for read/write requests */
63 uint64_t __attribute__((__aligned__(8))) id;
64 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
65 struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
66 };
67 struct blkif_x86_64_response {
68 uint64_t __attribute__((__aligned__(8))) id;
69 uint8_t operation; /* copied from request */
70 int16_t status; /* BLKIF_RSP_??? */
71 };
72 typedef struct blkif_x86_64_request blkif_x86_64_request_t;
73 typedef struct blkif_x86_64_response blkif_x86_64_response_t;
74
75 DEFINE_RING_TYPES(blkif_common, struct blkif_common_request, struct blkif_common_response);
76 DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request, struct blkif_x86_32_response);
77 DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request, struct blkif_x86_64_response);
78
79 /*
80 * Maximum number of requests that can be active for a given instance
81 * regardless of the protocol in use, based on the ring size. This constant
82 * facilitates resource pre-allocation in backend drivers since the size is
83 * known well in advance of attaching to a front end.
84 */
85 #define BLKIF_MAX_RING_REQUESTS(_sz) \
86 MAX(__RING_SIZE((blkif_x86_64_sring_t *)NULL, _sz), \
87 MAX(__RING_SIZE((blkif_x86_32_sring_t *)NULL, _sz), \
88 __RING_SIZE((blkif_sring_t *)NULL, _sz)))
89
90 /*
91 * The number of ring pages required to support a given number of requests
92 * for a given instance regardless of the protocol in use.
93 */
94 #define BLKIF_RING_PAGES(_entries) \
95 MAX(__RING_PAGES((blkif_x86_64_sring_t *)NULL, _entries), \
96 MAX(__RING_PAGES((blkif_x86_32_sring_t *)NULL, _entries), \
97 __RING_PAGES((blkif_sring_t *)NULL, _entries)))
98
99 union blkif_back_rings {
100 blkif_back_ring_t native;
101 blkif_common_back_ring_t common;
102 blkif_x86_32_back_ring_t x86_32;
103 blkif_x86_64_back_ring_t x86_64;
104 };
105 typedef union blkif_back_rings blkif_back_rings_t;
106
107 enum blkif_protocol {
108 BLKIF_PROTOCOL_NATIVE = 1,
109 BLKIF_PROTOCOL_X86_32 = 2,
110 BLKIF_PROTOCOL_X86_64 = 3,
111 };
112
blkif_get_x86_32_req(blkif_request_t * dst,blkif_x86_32_request_t * src)113 static void inline blkif_get_x86_32_req(blkif_request_t *dst, blkif_x86_32_request_t *src)
114 {
115 int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
116 dst->operation = src->operation;
117 dst->nr_segments = src->nr_segments;
118 dst->handle = src->handle;
119 dst->id = src->id;
120 dst->sector_number = src->sector_number;
121 __compiler_membar();
122 if (n > dst->nr_segments)
123 n = dst->nr_segments;
124 for (i = 0; i < n; i++)
125 dst->seg[i] = src->seg[i];
126 }
127
blkif_get_x86_64_req(blkif_request_t * dst,blkif_x86_64_request_t * src)128 static void inline blkif_get_x86_64_req(blkif_request_t *dst, blkif_x86_64_request_t *src)
129 {
130 int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
131 dst->operation = src->operation;
132 dst->nr_segments = src->nr_segments;
133 dst->handle = src->handle;
134 dst->id = src->id;
135 dst->sector_number = src->sector_number;
136 __compiler_membar();
137 if (n > dst->nr_segments)
138 n = dst->nr_segments;
139 for (i = 0; i < n; i++)
140 dst->seg[i] = src->seg[i];
141 }
142
143 #endif /* __XEN_BLKIF_H__ */
144