1 /*
2 * PVH Option ROM for fw_cfg DMA
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, see <http://www.gnu.org/licenses/>.
16 *
17 * Copyright (c) 2019 Red Hat Inc.
18 * Authors:
19 * Stefano Garzarella <sgarzare@redhat.com>
20 */
21
22 asm (".code32"); /* this code will be executed in protected mode */
23
24 #include <stddef.h>
25 #include <stdint.h>
26 #include "optrom.h"
27 #include "optrom_fw_cfg.h"
28 #include "../../include/hw/xen/start_info.h"
29
30 #define RSDP_SIGNATURE 0x2052545020445352LL /* "RSD PTR " */
31 #define RSDP_AREA_ADDR 0x000E0000
32 #define RSDP_AREA_SIZE 0x00020000
33 #define EBDA_BASE_ADDR 0x0000040E
34 #define EBDA_SIZE 1024
35
36 #define E820_MAXENTRIES 128
37 #define CMDLINE_BUFSIZE 4096
38
39 /* e820 table filled in pvh.S using int 0x15 */
40 struct pvh_e820_table {
41 uint32_t entries;
42 uint32_t reserved;
43 struct hvm_memmap_table_entry table[E820_MAXENTRIES];
44 };
45
46 struct pvh_e820_table pvh_e820 asm("pvh_e820") __attribute__ ((aligned));
47
48 static struct hvm_start_info start_info;
49 static struct hvm_modlist_entry ramdisk_mod;
50 static uint8_t cmdline_buffer[CMDLINE_BUFSIZE];
51
52
53 /* Search RSDP signature. */
search_rsdp(uint32_t start_addr,uint32_t end_addr)54 static uintptr_t search_rsdp(uint32_t start_addr, uint32_t end_addr)
55 {
56 uint64_t *rsdp_p;
57
58 /* RSDP signature is always on a 16 byte boundary */
59 for (rsdp_p = (uint64_t *)start_addr; rsdp_p < (uint64_t *)end_addr;
60 rsdp_p += 2) {
61 if (*rsdp_p == RSDP_SIGNATURE) {
62 return (uintptr_t)rsdp_p;
63 }
64 }
65
66 return 0;
67 }
68
69 /* Force the asm name without leading underscore, even on Win32. */
70 extern void pvh_load_kernel(void) asm("pvh_load_kernel");
71
pvh_load_kernel(void)72 void pvh_load_kernel(void)
73 {
74 void *cmdline_addr = &cmdline_buffer;
75 void *kernel_entry, *initrd_addr;
76 uint32_t cmdline_size, initrd_size, fw_cfg_version = bios_cfg_version();
77
78 start_info.magic = XEN_HVM_START_MAGIC_VALUE;
79 start_info.version = 1;
80
81 /*
82 * pvh_e820 is filled in the pvh.S before to switch in protected mode,
83 * because we can use int 0x15 only in real mode.
84 */
85 start_info.memmap_entries = pvh_e820.entries;
86 start_info.memmap_paddr = (uintptr_t)pvh_e820.table;
87
88 /*
89 * Search RSDP in the main BIOS area below 1 MB.
90 * SeaBIOS store the RSDP in this area, so we try it first.
91 */
92 start_info.rsdp_paddr = search_rsdp(RSDP_AREA_ADDR,
93 RSDP_AREA_ADDR + RSDP_AREA_SIZE);
94
95 /* Search RSDP in the EBDA if it is not found */
96 if (!start_info.rsdp_paddr) {
97 /*
98 * Th EBDA address is stored at EBDA_BASE_ADDR. It contains 2 bytes
99 * segment pointer to EBDA, so we must convert it to a linear address.
100 */
101 uint32_t ebda_paddr = ((uint32_t)*((uint16_t *)EBDA_BASE_ADDR)) << 4;
102 if (ebda_paddr > 0x400) {
103 uint32_t *ebda = (uint32_t *)ebda_paddr;
104
105 start_info.rsdp_paddr = search_rsdp(*ebda, *ebda + EBDA_SIZE);
106 }
107 }
108
109 bios_cfg_read_entry(&cmdline_size, FW_CFG_CMDLINE_SIZE, 4, fw_cfg_version);
110 bios_cfg_read_entry(cmdline_addr, FW_CFG_CMDLINE_DATA, cmdline_size,
111 fw_cfg_version);
112 start_info.cmdline_paddr = (uintptr_t)cmdline_addr;
113
114 /* Check if we have the initrd to load */
115 bios_cfg_read_entry(&initrd_size, FW_CFG_INITRD_SIZE, 4, fw_cfg_version);
116 if (initrd_size) {
117 bios_cfg_read_entry(&initrd_addr, FW_CFG_INITRD_ADDR, 4,
118 fw_cfg_version);
119 bios_cfg_read_entry(initrd_addr, FW_CFG_INITRD_DATA, initrd_size,
120 fw_cfg_version);
121
122 ramdisk_mod.paddr = (uintptr_t)initrd_addr;
123 ramdisk_mod.size = initrd_size;
124
125 /* The first module is always ramdisk. */
126 start_info.modlist_paddr = (uintptr_t)&ramdisk_mod;
127 start_info.nr_modules = 1;
128 }
129
130 bios_cfg_read_entry(&kernel_entry, FW_CFG_KERNEL_ENTRY, 4, fw_cfg_version);
131
132 asm volatile("jmp *%1" : : "b"(&start_info), "c"(kernel_entry));
133 }
134