hw/i386/pc_sysfw_ovmf.c

   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 "cpu.h"
  30
  31 #define OVMF_TABLE_FOOTER_GUID "96b582de-1fb2-45f7-baea-a366c55a082d"
  32
  33 static const int bytes_after_table_footer = 32;
  34
  35 static bool ovmf_flash_parsed;
  36 static uint8_t *ovmf_table;
  37 static int ovmf_table_len;
  38
  39 void pc_system_parse_ovmf_flash(uint8_t *flash_ptr, size_t flash_size)
  40 {
  41     uint8_t *ptr;
  42     QemuUUID guid;
  43     int tot_len;
  44
  45     /* should only be called once */
  46     if (ovmf_flash_parsed) {
  47         return;
  48     }
  49
  50     ovmf_flash_parsed = true;
  51
  52     if (flash_size < TARGET_PAGE_SIZE) {
  53         return;
  54     }
  55
  56     /*
  57      * if this is OVMF there will be a table footer
  58      * guid 48 bytes before the end of the flash file
  59      * (= 32 bytes after the table + 16 bytes the GUID itself).
  60      * If it's not found, silently abort the flash parsing.
  61      */
  62     qemu_uuid_parse(OVMF_TABLE_FOOTER_GUID, &guid);
  63     guid = qemu_uuid_bswap(guid); /* guids are LE */
  64     ptr = flash_ptr + flash_size - (bytes_after_table_footer + sizeof(guid));
  65     if (!qemu_uuid_is_equal((QemuUUID *)ptr, &guid)) {
  66         return;
  67     }
  68
  69     /* if found, just before is two byte table length */
  70     ptr -= sizeof(uint16_t);
  71     tot_len = le16_to_cpu(*(uint16_t *)ptr) - sizeof(guid) - sizeof(uint16_t);
  72
  73     if (tot_len < 0 || tot_len > (ptr - flash_ptr)) {
  74         error_report("OVMF table has invalid size %d", tot_len);
  75         return;
  76     }
  77
  78     if (tot_len == 0) {
  79         /* no entries in the OVMF table */
  80         return;
  81     }
  82
  83     ovmf_table = g_malloc(tot_len);
  84     ovmf_table_len = tot_len;
  85
  86     /*
  87      * ptr is the foot of the table, so copy it all to the newly
  88      * allocated ovmf_table and then set the ovmf_table pointer
  89      * to the table foot
  90      */
  91     memcpy(ovmf_table, ptr - tot_len, tot_len);
  92     ovmf_table += tot_len;
  93 }
  94
  95 /**
  96  * pc_system_ovmf_table_find - Find the data associated with an entry in OVMF's
  97  * reset vector GUIDed table.
  98  *
  99  * @entry: GUID string of the entry to lookup
 100  * @data: Filled with a pointer to the entry's value (if not NULL)
 101  * @data_len: Filled with the length of the entry's value (if not NULL). Pass
 102  *            NULL here if the length of data is known.
 103  *
 104  * Return: true if the entry was found in the OVMF table; false otherwise.
 105  */
 106 bool pc_system_ovmf_table_find(const char *entry, uint8_t **data,
 107                                int *data_len)
 108 {
 109     uint8_t *ptr = ovmf_table;
 110     int tot_len = ovmf_table_len;
 111     QemuUUID entry_guid;
 112
 113     assert(ovmf_flash_parsed);
 114
 115     if (qemu_uuid_parse(entry, &entry_guid) < 0) {
 116         return false;
 117     }
 118
 119     if (!ptr) {
 120         return false;
 121     }
 122
 123     entry_guid = qemu_uuid_bswap(entry_guid); /* guids are LE */
 124     while (tot_len >= sizeof(QemuUUID) + sizeof(uint16_t)) {
 125         int len;
 126         QemuUUID *guid;
 127
 128         /*
 129          * The data structure is
 130          *   arbitrary length data
 131          *   2 byte length of entire entry
 132          *   16 byte guid
 133          */
 134         guid = (QemuUUID *)(ptr - sizeof(QemuUUID));
 135         len = le16_to_cpu(*(uint16_t *)(ptr - sizeof(QemuUUID) -
 136                                         sizeof(uint16_t)));
 137
 138         /*
 139          * just in case the table is corrupt, wouldn't want to spin in
 140          * the zero case
 141          */
 142         if (len < sizeof(QemuUUID) + sizeof(uint16_t)) {
 143             return false;
 144         } else if (len > tot_len) {
 145             return false;
 146         }
 147
 148         ptr -= len;
 149         tot_len -= len;
 150         if (qemu_uuid_is_equal(guid, &entry_guid)) {
 151             if (data) {
 152                 *data = ptr;
 153             }
 154             if (data_len) {
 155                 *data_len = len - sizeof(QemuUUID) - sizeof(uint16_t);
 156             }
 157             return true;
 158         }
 159     }
 160     return false;
 161 }