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 #include "xen-ops.h"
  20
  21 static efi_char16_t vendor[100] __initdata;
  22
  23 static efi_system_table_t efi_systab_xen __initdata = {
  24         .hdr = {
  25                 .signature      = EFI_SYSTEM_TABLE_SIGNATURE,
  26                 .revision       = 0, /* Initialized later. */
  27                 .headersize     = 0, /* Ignored by Linux Kernel. */
  28                 .crc32          = 0, /* Ignored by Linux Kernel. */
  29                 .reserved       = 0
  30         },
  31         .fw_vendor      = EFI_INVALID_TABLE_ADDR, /* Initialized later. */
  32         .fw_revision    = 0,                      /* Initialized later. */
  33         .con_in_handle  = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
  34         .con_in         = NULL,                   /* Not used under Xen. */
  35         .con_out_handle = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
  36         .con_out        = NULL,                   /* Not used under Xen. */
  37         .stderr_handle  = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
  38         .stderr         = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
  39         .runtime        = (efi_runtime_services_t *)EFI_INVALID_TABLE_ADDR,
  40                                                   /* Not used under Xen. */
  41         .boottime       = (efi_boot_services_t *)EFI_INVALID_TABLE_ADDR,
  42                                                   /* Not used under Xen. */
  43         .nr_tables      = 0,                      /* Initialized later. */
  44         .tables         = EFI_INVALID_TABLE_ADDR  /* Initialized later. */
  45 };
  46
  47 static efi_system_table_t __init *xen_efi_probe(void)
  48 {
  49         struct xen_platform_op op = {
  50                 .cmd = XENPF_firmware_info,
  51                 .u.firmware_info = {
  52                         .type = XEN_FW_EFI_INFO,
  53                         .index = XEN_FW_EFI_CONFIG_TABLE
  54                 }
  55         };
  56         union xenpf_efi_info *info = &op.u.firmware_info.u.efi_info;
  57
  58         if (!xen_initial_domain() || HYPERVISOR_platform_op(&op) < 0)
  59                 return NULL;
  60
  61         /* Here we know that Xen runs on EFI platform. */
  62         xen_efi_runtime_setup();
  63
  64         efi_systab_xen.tables = info->cfg.addr;
  65         efi_systab_xen.nr_tables = info->cfg.nent;
  66
  67         op.cmd = XENPF_firmware_info;
  68         op.u.firmware_info.type = XEN_FW_EFI_INFO;
  69         op.u.firmware_info.index = XEN_FW_EFI_VENDOR;
  70         info->vendor.bufsz = sizeof(vendor);
  71         set_xen_guest_handle(info->vendor.name, vendor);
  72
  73         if (HYPERVISOR_platform_op(&op) == 0) {
  74                 efi_systab_xen.fw_vendor = __pa_symbol(vendor);
  75                 efi_systab_xen.fw_revision = info->vendor.revision;
  76         } else
  77                 efi_systab_xen.fw_vendor = __pa_symbol(L"UNKNOWN");
  78
  79         op.cmd = XENPF_firmware_info;
  80         op.u.firmware_info.type = XEN_FW_EFI_INFO;
  81         op.u.firmware_info.index = XEN_FW_EFI_VERSION;
  82
  83         if (HYPERVISOR_platform_op(&op) == 0)
  84                 efi_systab_xen.hdr.revision = info->version;
  85
  86         op.cmd = XENPF_firmware_info;
  87         op.u.firmware_info.type = XEN_FW_EFI_INFO;
  88         op.u.firmware_info.index = XEN_FW_EFI_RT_VERSION;
  89
  90         if (HYPERVISOR_platform_op(&op) == 0)
  91                 efi.runtime_version = info->version;
  92
  93         return &efi_systab_xen;
  94 }
  95
  96 /*
  97  * Determine whether we're in secure boot mode.
  98  */
  99 static enum efi_secureboot_mode xen_efi_get_secureboot(void)
 100 {
 101         static efi_guid_t shim_guid = EFI_SHIM_LOCK_GUID;
 102         enum efi_secureboot_mode mode;
 103         efi_status_t status;
 104         u8 moksbstate;
 105         unsigned long size;
 106
 107         mode = efi_get_secureboot_mode(efi.get_variable);
 108         if (mode == efi_secureboot_mode_unknown) {
 109                 pr_err("Could not determine UEFI Secure Boot status.\n");
 110                 return efi_secureboot_mode_unknown;
 111         }
 112         if (mode != efi_secureboot_mode_enabled)
 113                 return mode;
 114
 115         /* See if a user has put the shim into insecure mode. */
 116         size = sizeof(moksbstate);
 117         status = efi.get_variable(L"MokSBStateRT", &shim_guid,
 118                                   NULL, &size, &moksbstate);
 119
 120         /* If it fails, we don't care why. Default to secure. */
 121         if (status != EFI_SUCCESS)
 122                 goto secure_boot_enabled;
 123
 124         if (moksbstate == 1)
 125                 return efi_secureboot_mode_disabled;
 126
 127  secure_boot_enabled:
 128         pr_info("UEFI Secure Boot is enabled.\n");
 129         return efi_secureboot_mode_enabled;
 130 }
 131
 132 void __init xen_efi_init(struct boot_params *boot_params)
 133 {
 134         efi_system_table_t *efi_systab_xen;
 135
 136         efi_systab_xen = xen_efi_probe();
 137
 138         if (efi_systab_xen == NULL)
 139                 return;
 140
 141         strscpy((char *)&boot_params->efi_info.efi_loader_signature, "Xen",
 142                         sizeof(boot_params->efi_info.efi_loader_signature));
 143         boot_params->efi_info.efi_systab = (__u32)__pa(efi_systab_xen);
 144         boot_params->efi_info.efi_systab_hi = (__u32)(__pa(efi_systab_xen) >> 32);
 145
 146         boot_params->secure_boot = xen_efi_get_secureboot();
 147
 148         set_bit(EFI_BOOT, &efi.flags);
 149         set_bit(EFI_PARAVIRT, &efi.flags);
 150         set_bit(EFI_64BIT, &efi.flags);
 151 }