x86/xen/efi.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Copyright (c) 2014 Oracle Co., Daniel Kiper
0004  */
0005
0006 #include <linux/bitops.h>
0007 #include <linux/efi.h>
0008 #include <linux/init.h>
0009 #include <linux/string.h>
0010
0011 #include <xen/xen.h>
0012 #include <xen/xen-ops.h>
0013 #include <xen/interface/platform.h>
0014
0015 #include <asm/page.h>
0016 #include <asm/setup.h>
0017 #include <asm/xen/hypercall.h>
0018
0019 static efi_char16_t vendor[100] __initdata;
0020
0021 static efi_system_table_t efi_systab_xen __initdata = {
0022     .hdr = {
0023         .signature  = EFI_SYSTEM_TABLE_SIGNATURE,
0024         .revision   = 0, /* Initialized later. */
0025         .headersize = 0, /* Ignored by Linux Kernel. */
0026         .crc32      = 0, /* Ignored by Linux Kernel. */
0027         .reserved   = 0
0028     },
0029     .fw_vendor  = EFI_INVALID_TABLE_ADDR, /* Initialized later. */
0030     .fw_revision    = 0,              /* Initialized later. */
0031     .con_in_handle  = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
0032     .con_in     = NULL,           /* Not used under Xen. */
0033     .con_out_handle = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
0034     .con_out    = NULL,           /* Not used under Xen. */
0035     .stderr_handle  = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
0036     .stderr     = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
0037     .runtime    = (efi_runtime_services_t *)EFI_INVALID_TABLE_ADDR,
0038                           /* Not used under Xen. */
0039     .boottime   = (efi_boot_services_t *)EFI_INVALID_TABLE_ADDR,
0040                           /* Not used under Xen. */
0041     .nr_tables  = 0,              /* Initialized later. */
0042     .tables     = EFI_INVALID_TABLE_ADDR  /* Initialized later. */
0043 };
0044
0045 static efi_system_table_t __init *xen_efi_probe(void)
0046 {
0047     struct xen_platform_op op = {
0048         .cmd = XENPF_firmware_info,
0049         .u.firmware_info = {
0050             .type = XEN_FW_EFI_INFO,
0051             .index = XEN_FW_EFI_CONFIG_TABLE
0052         }
0053     };
0054     union xenpf_efi_info *info = &op.u.firmware_info.u.efi_info;
0055
0056     if (!xen_initial_domain() || HYPERVISOR_platform_op(&op) < 0)
0057         return NULL;
0058
0059     /* Here we know that Xen runs on EFI platform. */
0060     xen_efi_runtime_setup();
0061
0062     efi_systab_xen.tables = info->cfg.addr;
0063     efi_systab_xen.nr_tables = info->cfg.nent;
0064
0065     op.cmd = XENPF_firmware_info;
0066     op.u.firmware_info.type = XEN_FW_EFI_INFO;
0067     op.u.firmware_info.index = XEN_FW_EFI_VENDOR;
0068     info->vendor.bufsz = sizeof(vendor);
0069     set_xen_guest_handle(info->vendor.name, vendor);
0070
0071     if (HYPERVISOR_platform_op(&op) == 0) {
0072         efi_systab_xen.fw_vendor = __pa_symbol(vendor);
0073         efi_systab_xen.fw_revision = info->vendor.revision;
0074     } else
0075         efi_systab_xen.fw_vendor = __pa_symbol(L"UNKNOWN");
0076
0077     op.cmd = XENPF_firmware_info;
0078     op.u.firmware_info.type = XEN_FW_EFI_INFO;
0079     op.u.firmware_info.index = XEN_FW_EFI_VERSION;
0080
0081     if (HYPERVISOR_platform_op(&op) == 0)
0082         efi_systab_xen.hdr.revision = info->version;
0083
0084     op.cmd = XENPF_firmware_info;
0085     op.u.firmware_info.type = XEN_FW_EFI_INFO;
0086     op.u.firmware_info.index = XEN_FW_EFI_RT_VERSION;
0087
0088     if (HYPERVISOR_platform_op(&op) == 0)
0089         efi.runtime_version = info->version;
0090
0091     return &efi_systab_xen;
0092 }
0093
0094 /*
0095  * Determine whether we're in secure boot mode.
0096  */
0097 static enum efi_secureboot_mode xen_efi_get_secureboot(void)
0098 {
0099     static efi_guid_t shim_guid = EFI_SHIM_LOCK_GUID;
0100     enum efi_secureboot_mode mode;
0101     efi_status_t status;
0102     u8 moksbstate;
0103     unsigned long size;
0104
0105     mode = efi_get_secureboot_mode(efi.get_variable);
0106     if (mode == efi_secureboot_mode_unknown) {
0107         pr_err("Could not determine UEFI Secure Boot status.\n");
0108         return efi_secureboot_mode_unknown;
0109     }
0110     if (mode != efi_secureboot_mode_enabled)
0111         return mode;
0112
0113     /* See if a user has put the shim into insecure mode. */
0114     size = sizeof(moksbstate);
0115     status = efi.get_variable(L"MokSBStateRT", &shim_guid,
0116                   NULL, &size, &moksbstate);
0117
0118     /* If it fails, we don't care why. Default to secure. */
0119     if (status != EFI_SUCCESS)
0120         goto secure_boot_enabled;
0121
0122     if (moksbstate == 1)
0123         return efi_secureboot_mode_disabled;
0124
0125  secure_boot_enabled:
0126     pr_info("UEFI Secure Boot is enabled.\n");
0127     return efi_secureboot_mode_enabled;
0128 }
0129
0130 void __init xen_efi_init(struct boot_params *boot_params)
0131 {
0132     efi_system_table_t *efi_systab_xen;
0133
0134     efi_systab_xen = xen_efi_probe();
0135
0136     if (efi_systab_xen == NULL)
0137         return;
0138
0139     strncpy((char *)&boot_params->efi_info.efi_loader_signature, "Xen",
0140             sizeof(boot_params->efi_info.efi_loader_signature));
0141     boot_params->efi_info.efi_systab = (__u32)__pa(efi_systab_xen);
0142     boot_params->efi_info.efi_systab_hi = (__u32)(__pa(efi_systab_xen) >> 32);
0143
0144     boot_params->secure_boot = xen_efi_get_secureboot();
0145
0146     set_bit(EFI_BOOT, &efi.flags);
0147     set_bit(EFI_PARAVIRT, &efi.flags);
0148     set_bit(EFI_64BIT, &efi.flags);
0149 }