arch/x86/xen/efi.c

   1 /*
   2  * Copyright (c) 2014 Oracle Co., Daniel Kiper
   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 along
  15  * with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include <linux/bitops.h>
  19 #include <linux/efi.h>
  20 #include <linux/init.h>
  21 #include <linux/string.h>
  22
  23 #include <xen/xen.h>
  24 #include <xen/xen-ops.h>
  25 #include <xen/interface/platform.h>
  26
  27 #include <asm/page.h>
  28 #include <asm/setup.h>
  29 #include <asm/xen/hypercall.h>
  30
  31 static efi_char16_t vendor[100] __initdata;
  32
  33 static efi_system_table_t efi_systab_xen __initdata = {
  34         .hdr = {
  35                 .signature      = EFI_SYSTEM_TABLE_SIGNATURE,
  36                 .revision       = 0, /* Initialized later. */
  37                 .headersize     = 0, /* Ignored by Linux Kernel. */
  38                 .crc32          = 0, /* Ignored by Linux Kernel. */
  39                 .reserved       = 0
  40         },
  41         .fw_vendor      = EFI_INVALID_TABLE_ADDR, /* Initialized later. */
  42         .fw_revision    = 0,                      /* Initialized later. */
  43         .con_in_handle  = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
  44         .con_in         = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
  45         .con_out_handle = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
  46         .con_out        = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
  47         .stderr_handle  = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
  48         .stderr         = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
  49         .runtime        = (efi_runtime_services_t *)EFI_INVALID_TABLE_ADDR,
  50                                                   /* Not used under Xen. */
  51         .boottime       = (efi_boot_services_t *)EFI_INVALID_TABLE_ADDR,
  52                                                   /* Not used under Xen. */
  53         .nr_tables      = 0,                      /* Initialized later. */
  54         .tables         = EFI_INVALID_TABLE_ADDR  /* Initialized later. */
  55 };
  56
  57 static efi_system_table_t __init *xen_efi_probe(void)
  58 {
  59         struct xen_platform_op op = {
  60                 .cmd = XENPF_firmware_info,
  61                 .u.firmware_info = {
  62                         .type = XEN_FW_EFI_INFO,
  63                         .index = XEN_FW_EFI_CONFIG_TABLE
  64                 }
  65         };
  66         union xenpf_efi_info *info = &op.u.firmware_info.u.efi_info;
  67
  68         if (!xen_initial_domain() || HYPERVISOR_platform_op(&op) < 0)
  69                 return NULL;
  70
  71         /* Here we know that Xen runs on EFI platform. */
  72
  73         efi.get_time                 = xen_efi_get_time;
  74         efi.set_time                 = xen_efi_set_time;
  75         efi.get_wakeup_time          = xen_efi_get_wakeup_time;
  76         efi.set_wakeup_time          = xen_efi_set_wakeup_time;
  77         efi.get_variable             = xen_efi_get_variable;
  78         efi.get_next_variable        = xen_efi_get_next_variable;
  79         efi.set_variable             = xen_efi_set_variable;
  80         efi.set_variable_nonblocking = xen_efi_set_variable;
  81         efi.query_variable_info      = xen_efi_query_variable_info;
  82         efi.query_variable_info_nonblocking = xen_efi_query_variable_info;
  83         efi.update_capsule           = xen_efi_update_capsule;
  84         efi.query_capsule_caps       = xen_efi_query_capsule_caps;
  85         efi.get_next_high_mono_count = xen_efi_get_next_high_mono_count;
  86         efi.reset_system             = xen_efi_reset_system;
  87
  88         efi_systab_xen.tables = info->cfg.addr;
  89         efi_systab_xen.nr_tables = info->cfg.nent;
  90
  91         op.cmd = XENPF_firmware_info;
  92         op.u.firmware_info.type = XEN_FW_EFI_INFO;
  93         op.u.firmware_info.index = XEN_FW_EFI_VENDOR;
  94         info->vendor.bufsz = sizeof(vendor);
  95         set_xen_guest_handle(info->vendor.name, vendor);
  96
  97         if (HYPERVISOR_platform_op(&op) == 0) {
  98                 efi_systab_xen.fw_vendor = __pa_symbol(vendor);
  99                 efi_systab_xen.fw_revision = info->vendor.revision;
 100         } else
 101                 efi_systab_xen.fw_vendor = __pa_symbol(L"UNKNOWN");
 102
 103         op.cmd = XENPF_firmware_info;
 104         op.u.firmware_info.type = XEN_FW_EFI_INFO;
 105         op.u.firmware_info.index = XEN_FW_EFI_VERSION;
 106
 107         if (HYPERVISOR_platform_op(&op) == 0)
 108                 efi_systab_xen.hdr.revision = info->version;
 109
 110         op.cmd = XENPF_firmware_info;
 111         op.u.firmware_info.type = XEN_FW_EFI_INFO;
 112         op.u.firmware_info.index = XEN_FW_EFI_RT_VERSION;
 113
 114         if (HYPERVISOR_platform_op(&op) == 0)
 115                 efi.runtime_version = info->version;
 116
 117         return &efi_systab_xen;
 118 }
 119
 120 /*
 121  * Determine whether we're in secure boot mode.
 122  *
 123  * Please keep the logic in sync with
 124  * drivers/firmware/efi/libstub/secureboot.c:efi_get_secureboot().
 125  */
 126 static enum efi_secureboot_mode xen_efi_get_secureboot(void)
 127 {
 128         static efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
 129         static efi_guid_t shim_guid = EFI_SHIM_LOCK_GUID;
 130         efi_status_t status;
 131         u8 moksbstate, secboot, setupmode;
 132         unsigned long size;
 133
 134         size = sizeof(secboot);
 135         status = efi.get_variable(L"SecureBoot", &efi_variable_guid,
 136                                   NULL, &size, &secboot);
 137
 138         if (status == EFI_NOT_FOUND)
 139                 return efi_secureboot_mode_disabled;
 140
 141         if (status != EFI_SUCCESS)
 142                 goto out_efi_err;
 143
 144         size = sizeof(setupmode);
 145         status = efi.get_variable(L"SetupMode", &efi_variable_guid,
 146                                   NULL, &size, &setupmode);
 147
 148         if (status != EFI_SUCCESS)
 149                 goto out_efi_err;
 150
 151         if (secboot == 0 || setupmode == 1)
 152                 return efi_secureboot_mode_disabled;
 153
 154         /* See if a user has put the shim into insecure mode. */
 155         size = sizeof(moksbstate);
 156         status = efi.get_variable(L"MokSBStateRT", &shim_guid,
 157                                   NULL, &size, &moksbstate);
 158
 159         /* If it fails, we don't care why. Default to secure. */
 160         if (status != EFI_SUCCESS)
 161                 goto secure_boot_enabled;
 162
 163         if (moksbstate == 1)
 164                 return efi_secureboot_mode_disabled;
 165
 166  secure_boot_enabled:
 167         pr_info("UEFI Secure Boot is enabled.\n");
 168         return efi_secureboot_mode_enabled;
 169
 170  out_efi_err:
 171         pr_err("Could not determine UEFI Secure Boot status.\n");
 172         return efi_secureboot_mode_unknown;
 173 }
 174
 175 void __init xen_efi_init(struct boot_params *boot_params)
 176 {
 177         efi_system_table_t *efi_systab_xen;
 178
 179         efi_systab_xen = xen_efi_probe();
 180
 181         if (efi_systab_xen == NULL)
 182                 return;
 183
 184         strncpy((char *)&boot_params->efi_info.efi_loader_signature, "Xen",
 185                         sizeof(boot_params->efi_info.efi_loader_signature));
 186         boot_params->efi_info.efi_systab = (__u32)__pa(efi_systab_xen);
 187         boot_params->efi_info.efi_systab_hi = (__u32)(__pa(efi_systab_xen) >> 32);
 188
 189         boot_params->secure_boot = xen_efi_get_secureboot();
 190
 191         set_bit(EFI_BOOT, &efi.flags);
 192         set_bit(EFI_PARAVIRT, &efi.flags);
 193         set_bit(EFI_64BIT, &efi.flags);
 194 }