1 /*
2 * QEMU PC System Firmware (OVMF specific)
3 *
4 * Copyright (c) 2003-2004 Fabrice Bellard
5 * Copyright (c) 2011-2012 Intel Corporation
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
23 * THE SOFTWARE.
24 */
25
26 #include "qemu/osdep.h"
27 #include "qemu/error-report.h"
28 #include "hw/i386/pc.h"
29 #include "exec/target_page.h"
30 #include "cpu.h"
31
32 #define OVMF_TABLE_FOOTER_GUID "96b582de-1fb2-45f7-baea-a366c55a082d"
33
34 static const int bytes_after_table_footer = 32;
35
36 static bool ovmf_flash_parsed;
37 static uint8_t *ovmf_table;
38 static int ovmf_table_len;
39
pc_system_parse_ovmf_flash(uint8_t * flash_ptr,size_t flash_size)40 void pc_system_parse_ovmf_flash(uint8_t *flash_ptr, size_t flash_size)
41 {
42 uint8_t *ptr;
43 QemuUUID guid;
44 int tot_len;
45
46 /* should only be called once */
47 if (ovmf_flash_parsed) {
48 return;
49 }
50
51 ovmf_flash_parsed = true;
52
53 if (flash_size < TARGET_PAGE_SIZE) {
54 return;
55 }
56
57 /*
58 * if this is OVMF there will be a table footer
59 * guid 48 bytes before the end of the flash file
60 * (= 32 bytes after the table + 16 bytes the GUID itself).
61 * If it's not found, silently abort the flash parsing.
62 */
63 qemu_uuid_parse(OVMF_TABLE_FOOTER_GUID, &guid);
64 guid = qemu_uuid_bswap(guid); /* guids are LE */
65 ptr = flash_ptr + flash_size - (bytes_after_table_footer + sizeof(guid));
66 if (!qemu_uuid_is_equal((QemuUUID *)ptr, &guid)) {
67 return;
68 }
69
70 /* if found, just before is two byte table length */
71 ptr -= sizeof(uint16_t);
72 tot_len = le16_to_cpu(*(uint16_t *)ptr) - sizeof(guid) - sizeof(uint16_t);
73
74 if (tot_len < 0 || tot_len > (ptr - flash_ptr)) {
75 error_report("OVMF table has invalid size %d", tot_len);
76 return;
77 }
78
79 if (tot_len == 0) {
80 /* no entries in the OVMF table */
81 return;
82 }
83
84 ovmf_table = g_malloc(tot_len);
85 ovmf_table_len = tot_len;
86
87 /*
88 * ptr is the foot of the table, so copy it all to the newly
89 * allocated ovmf_table and then set the ovmf_table pointer
90 * to the table foot
91 */
92 memcpy(ovmf_table, ptr - tot_len, tot_len);
93 ovmf_table += tot_len;
94 }
95
96 /**
97 * pc_system_ovmf_table_find - Find the data associated with an entry in OVMF's
98 * reset vector GUIDed table.
99 *
100 * @entry: GUID string of the entry to lookup
101 * @data: Filled with a pointer to the entry's value (if not NULL)
102 * @data_len: Filled with the length of the entry's value (if not NULL). Pass
103 * NULL here if the length of data is known.
104 *
105 * Return: true if the entry was found in the OVMF table; false otherwise.
106 */
pc_system_ovmf_table_find(const char * entry,uint8_t ** data,int * data_len)107 bool pc_system_ovmf_table_find(const char *entry, uint8_t **data,
108 int *data_len)
109 {
110 uint8_t *ptr = ovmf_table;
111 int tot_len = ovmf_table_len;
112 QemuUUID entry_guid;
113
114 assert(ovmf_flash_parsed);
115
116 if (qemu_uuid_parse(entry, &entry_guid) < 0) {
117 return false;
118 }
119
120 if (!ptr) {
121 return false;
122 }
123
124 entry_guid = qemu_uuid_bswap(entry_guid); /* guids are LE */
125 while (tot_len >= sizeof(QemuUUID) + sizeof(uint16_t)) {
126 int len;
127 QemuUUID *guid;
128
129 /*
130 * The data structure is
131 * arbitrary length data
132 * 2 byte length of entire entry
133 * 16 byte guid
134 */
135 guid = (QemuUUID *)(ptr - sizeof(QemuUUID));
136 len = le16_to_cpu(*(uint16_t *)(ptr - sizeof(QemuUUID) -
137 sizeof(uint16_t)));
138
139 /*
140 * just in case the table is corrupt, wouldn't want to spin in
141 * the zero case
142 */
143 if (len < sizeof(QemuUUID) + sizeof(uint16_t)) {
144 return false;
145 } else if (len > tot_len) {
146 return false;
147 }
148
149 ptr -= len;
150 tot_len -= len;
151 if (qemu_uuid_is_equal(guid, &entry_guid)) {
152 if (data) {
153 *data = ptr;
154 }
155 if (data_len) {
156 *data_len = len - sizeof(QemuUUID) - sizeof(uint16_t);
157 }
158 return true;
159 }
160 }
161 return false;
162 }
163