arch/x86/xen/efi.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2014 Oracle Co., Daniel Kiper
   4  */
   5
   6 #include <linux/bitops.h>
   7 #include <linux/efi.h>
   8 #include <linux/init.h>
   9 #include <linux/string.h>
  10
  11 #include <xen/xen.h>
  12 #include <xen/xen-ops.h>
  13 #include <xen/interface/platform.h>
  14
  15 #include <asm/page.h>
  16 #include <asm/setup.h>
  17 #include <asm/xen/hypercall.h>
  18
  19 static efi_char16_t vendor[100] __initdata;
  20
  21 static efi_system_table_t efi_systab_xen __initdata = {
  22         .hdr = {
  23                 .signature      = EFI_SYSTEM_TABLE_SIGNATURE,
  24                 .revision       = 0, /* Initialized later. */
  25                 .headersize     = 0, /* Ignored by Linux Kernel. */
  26                 .crc32          = 0, /* Ignored by Linux Kernel. */
  27                 .reserved       = 0
  28         },
  29         .fw_vendor      = EFI_INVALID_TABLE_ADDR, /* Initialized later. */
  30         .fw_revision    = 0,                      /* Initialized later. */
  31         .con_in_handle  = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
  32         .con_in         = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
  33         .con_out_handle = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
  34         .con_out        = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
  35         .stderr_handle  = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
  36         .stderr         = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
  37         .runtime        = (efi_runtime_services_t *)EFI_INVALID_TABLE_ADDR,
  38                                                   /* Not used under Xen. */
  39         .boottime       = (efi_boot_services_t *)EFI_INVALID_TABLE_ADDR,
  40                                                   /* Not used under Xen. */
  41         .nr_tables      = 0,                      /* Initialized later. */
  42         .tables         = EFI_INVALID_TABLE_ADDR  /* Initialized later. */
  43 };
  44
  45 static efi_system_table_t __init *xen_efi_probe(void)
  46 {
  47         struct xen_platform_op op = {
  48                 .cmd = XENPF_firmware_info,
  49                 .u.firmware_info = {
  50                         .type = XEN_FW_EFI_INFO,
  51                         .index = XEN_FW_EFI_CONFIG_TABLE
  52                 }
  53         };
  54         union xenpf_efi_info *info = &op.u.firmware_info.u.efi_info;
  55
  56         if (!xen_initial_domain() || HYPERVISOR_platform_op(&op) < 0)
  57                 return NULL;
  58
  59         /* Here we know that Xen runs on EFI platform. */
  60
  61         efi.get_time                 = xen_efi_get_time;
  62         efi.set_time                 = xen_efi_set_time;
  63         efi.get_wakeup_time          = xen_efi_get_wakeup_time;
  64         efi.set_wakeup_time          = xen_efi_set_wakeup_time;
  65         efi.get_variable             = xen_efi_get_variable;
  66         efi.get_next_variable        = xen_efi_get_next_variable;
  67         efi.set_variable             = xen_efi_set_variable;
  68         efi.query_variable_info      = xen_efi_query_variable_info;
  69         efi.update_capsule           = xen_efi_update_capsule;
  70         efi.query_capsule_caps       = xen_efi_query_capsule_caps;
  71         efi.get_next_high_mono_count = xen_efi_get_next_high_mono_count;
  72         efi.reset_system             = xen_efi_reset_system;
  73
  74         efi_systab_xen.tables = info->cfg.addr;
  75         efi_systab_xen.nr_tables = info->cfg.nent;
  76
  77         op.cmd = XENPF_firmware_info;
  78         op.u.firmware_info.type = XEN_FW_EFI_INFO;
  79         op.u.firmware_info.index = XEN_FW_EFI_VENDOR;
  80         info->vendor.bufsz = sizeof(vendor);
  81         set_xen_guest_handle(info->vendor.name, vendor);
  82
  83         if (HYPERVISOR_platform_op(&op) == 0) {
  84                 efi_systab_xen.fw_vendor = __pa_symbol(vendor);
  85                 efi_systab_xen.fw_revision = info->vendor.revision;
  86         } else
  87                 efi_systab_xen.fw_vendor = __pa_symbol(L"UNKNOWN");
  88
  89         op.cmd = XENPF_firmware_info;
  90         op.u.firmware_info.type = XEN_FW_EFI_INFO;
  91         op.u.firmware_info.index = XEN_FW_EFI_VERSION;
  92
  93         if (HYPERVISOR_platform_op(&op) == 0)
  94                 efi_systab_xen.hdr.revision = info->version;
  95
  96         op.cmd = XENPF_firmware_info;
  97         op.u.firmware_info.type = XEN_FW_EFI_INFO;
  98         op.u.firmware_info.index = XEN_FW_EFI_RT_VERSION;
  99
 100         if (HYPERVISOR_platform_op(&op) == 0)
 101                 efi.runtime_version = info->version;
 102
 103         return &efi_systab_xen;
 104 }
 105
 106 /*
 107  * Determine whether we're in secure boot mode.
 108  *
 109  * Please keep the logic in sync with
 110  * drivers/firmware/efi/libstub/secureboot.c:efi_get_secureboot().
 111  */
 112 static enum efi_secureboot_mode xen_efi_get_secureboot(void)
 113 {
 114         static efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
 115         static efi_guid_t shim_guid = EFI_SHIM_LOCK_GUID;
 116         efi_status_t status;
 117         u8 moksbstate, secboot, setupmode;
 118         unsigned long size;
 119
 120         size = sizeof(secboot);
 121         status = efi.get_variable(L"SecureBoot", &efi_variable_guid,
 122                                   NULL, &size, &secboot);
 123
 124         if (status == EFI_NOT_FOUND)
 125                 return efi_secureboot_mode_disabled;
 126
 127         if (status != EFI_SUCCESS)
 128                 goto out_efi_err;
 129
 130         size = sizeof(setupmode);
 131         status = efi.get_variable(L"SetupMode", &efi_variable_guid,
 132                                   NULL, &size, &setupmode);
 133
 134         if (status != EFI_SUCCESS)
 135                 goto out_efi_err;
 136
 137         if (secboot == 0 || setupmode == 1)
 138                 return efi_secureboot_mode_disabled;
 139
 140         /* See if a user has put the shim into insecure mode. */
 141         size = sizeof(moksbstate);
 142         status = efi.get_variable(L"MokSBStateRT", &shim_guid,
 143                                   NULL, &size, &moksbstate);
 144
 145         /* If it fails, we don't care why. Default to secure. */
 146         if (status != EFI_SUCCESS)
 147                 goto secure_boot_enabled;
 148
 149         if (moksbstate == 1)
 150                 return efi_secureboot_mode_disabled;
 151
 152  secure_boot_enabled:
 153         pr_info("UEFI Secure Boot is enabled.\n");
 154         return efi_secureboot_mode_enabled;
 155
 156  out_efi_err:
 157         pr_err("Could not determine UEFI Secure Boot status.\n");
 158         return efi_secureboot_mode_unknown;
 159 }
 160
 161 void __init xen_efi_init(void)
 162 {
 163         efi_system_table_t *efi_systab_xen;
 164
 165         efi_systab_xen = xen_efi_probe();
 166
 167         if (efi_systab_xen == NULL)
 168                 return;
 169
 170         strncpy((char *)&boot_params.efi_info.efi_loader_signature, "Xen",
 171                         sizeof(boot_params.efi_info.efi_loader_signature));
 172         boot_params.efi_info.efi_systab = (__u32)__pa(efi_systab_xen);
 173         boot_params.efi_info.efi_systab_hi = (__u32)(__pa(efi_systab_xen) >> 32);
 174
 175         boot_params.secure_boot = xen_efi_get_secureboot();
 176
 177         set_bit(EFI_BOOT, &efi.flags);
 178         set_bit(EFI_PARAVIRT, &efi.flags);
 179         set_bit(EFI_64BIT, &efi.flags);
 180 }