pc-bios/optionrom/pvh_main.c

   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          2048
  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. */
  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
  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 }