1 | /* |
2 | * Hard disk geometry utilities |
3 | * |
4 | * Copyright (C) 2012 Red Hat, Inc. |
5 | * |
6 | * This work is licensed under the terms of the GNU GPL, version 2 or later. |
7 | * See the COPYING file in the top-level directory. |
8 | * |
9 | * This file incorporates work covered by the following copyright and |
10 | * permission notice: |
11 | * |
12 | * Copyright (c) 2003 Fabrice Bellard |
13 | * |
14 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
15 | * of this software and associated documentation files (the "Software"), to deal |
16 | * in the Software without restriction, including without limitation the rights |
17 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
18 | * copies of the Software, and to permit persons to whom the Software is |
19 | * furnished to do so, subject to the following conditions: |
20 | * |
21 | * The above copyright notice and this permission notice shall be included in |
22 | * all copies or substantial portions of the Software. |
23 | * |
24 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
25 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
26 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
27 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
28 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
29 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
30 | * THE SOFTWARE. |
31 | */ |
32 | |
33 | #include "qemu/osdep.h" |
34 | #include "sysemu/block-backend.h" |
35 | #include "qapi/qapi-types-block.h" |
36 | #include "qemu/bswap.h" |
37 | #include "hw/block/block.h" |
38 | #include "trace.h" |
39 | |
40 | struct partition { |
41 | uint8_t boot_ind; /* 0x80 - active */ |
42 | uint8_t head; /* starting head */ |
43 | uint8_t sector; /* starting sector */ |
44 | uint8_t cyl; /* starting cylinder */ |
45 | uint8_t sys_ind; /* What partition type */ |
46 | uint8_t end_head; /* end head */ |
47 | uint8_t end_sector; /* end sector */ |
48 | uint8_t end_cyl; /* end cylinder */ |
49 | uint32_t start_sect; /* starting sector counting from 0 */ |
50 | uint32_t nr_sects; /* nr of sectors in partition */ |
51 | } QEMU_PACKED; |
52 | |
53 | /* try to guess the disk logical geometry from the MSDOS partition table. |
54 | Return 0 if OK, -1 if could not guess */ |
55 | static int guess_disk_lchs(BlockBackend *blk, |
56 | int *pcylinders, int *pheads, int *psectors) |
57 | { |
58 | uint8_t buf[BDRV_SECTOR_SIZE]; |
59 | int i, heads, sectors, cylinders; |
60 | struct partition *p; |
61 | uint32_t nr_sects; |
62 | uint64_t nb_sectors; |
63 | |
64 | blk_get_geometry(blk, &nb_sectors); |
65 | |
66 | if (blk_pread(blk, 0, buf, BDRV_SECTOR_SIZE) < 0) { |
67 | return -1; |
68 | } |
69 | /* test msdos magic */ |
70 | if (buf[510] != 0x55 || buf[511] != 0xaa) { |
71 | return -1; |
72 | } |
73 | for (i = 0; i < 4; i++) { |
74 | p = ((struct partition *)(buf + 0x1be)) + i; |
75 | nr_sects = le32_to_cpu(p->nr_sects); |
76 | if (nr_sects && p->end_head) { |
77 | /* We make the assumption that the partition terminates on |
78 | a cylinder boundary */ |
79 | heads = p->end_head + 1; |
80 | sectors = p->end_sector & 63; |
81 | if (sectors == 0) { |
82 | continue; |
83 | } |
84 | cylinders = nb_sectors / (heads * sectors); |
85 | if (cylinders < 1 || cylinders > 16383) { |
86 | continue; |
87 | } |
88 | *pheads = heads; |
89 | *psectors = sectors; |
90 | *pcylinders = cylinders; |
91 | trace_hd_geometry_lchs_guess(blk, cylinders, heads, sectors); |
92 | return 0; |
93 | } |
94 | } |
95 | return -1; |
96 | } |
97 | |
98 | static void guess_chs_for_size(BlockBackend *blk, |
99 | uint32_t *pcyls, uint32_t *pheads, uint32_t *psecs) |
100 | { |
101 | uint64_t nb_sectors; |
102 | int cylinders; |
103 | |
104 | blk_get_geometry(blk, &nb_sectors); |
105 | |
106 | cylinders = nb_sectors / (16 * 63); |
107 | if (cylinders > 16383) { |
108 | cylinders = 16383; |
109 | } else if (cylinders < 2) { |
110 | cylinders = 2; |
111 | } |
112 | *pcyls = cylinders; |
113 | *pheads = 16; |
114 | *psecs = 63; |
115 | } |
116 | |
117 | void hd_geometry_guess(BlockBackend *blk, |
118 | uint32_t *pcyls, uint32_t *pheads, uint32_t *psecs, |
119 | int *ptrans) |
120 | { |
121 | int cylinders, heads, secs, translation; |
122 | HDGeometry geo; |
123 | |
124 | /* Try to probe the backing device geometry, otherwise fallback |
125 | to the old logic. (as of 12/2014 probing only succeeds on DASDs) */ |
126 | if (blk_probe_geometry(blk, &geo) == 0) { |
127 | *pcyls = geo.cylinders; |
128 | *psecs = geo.sectors; |
129 | *pheads = geo.heads; |
130 | translation = BIOS_ATA_TRANSLATION_NONE; |
131 | } else if (guess_disk_lchs(blk, &cylinders, &heads, &secs) < 0) { |
132 | /* no LCHS guess: use a standard physical disk geometry */ |
133 | guess_chs_for_size(blk, pcyls, pheads, psecs); |
134 | translation = hd_bios_chs_auto_trans(*pcyls, *pheads, *psecs); |
135 | } else if (heads > 16) { |
136 | /* LCHS guess with heads > 16 means that a BIOS LBA |
137 | translation was active, so a standard physical disk |
138 | geometry is OK */ |
139 | guess_chs_for_size(blk, pcyls, pheads, psecs); |
140 | translation = *pcyls * *pheads <= 131072 |
141 | ? BIOS_ATA_TRANSLATION_LARGE |
142 | : BIOS_ATA_TRANSLATION_LBA; |
143 | } else { |
144 | /* LCHS guess with heads <= 16: use as physical geometry */ |
145 | *pcyls = cylinders; |
146 | *pheads = heads; |
147 | *psecs = secs; |
148 | /* disable any translation to be in sync with |
149 | the logical geometry */ |
150 | translation = BIOS_ATA_TRANSLATION_NONE; |
151 | } |
152 | if (ptrans) { |
153 | *ptrans = translation; |
154 | } |
155 | trace_hd_geometry_guess(blk, *pcyls, *pheads, *psecs, translation); |
156 | } |
157 | |
158 | int hd_bios_chs_auto_trans(uint32_t cyls, uint32_t heads, uint32_t secs) |
159 | { |
160 | return cyls <= 1024 && heads <= 16 && secs <= 63 |
161 | ? BIOS_ATA_TRANSLATION_NONE |
162 | : BIOS_ATA_TRANSLATION_LBA; |
163 | } |
164 | |