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 = NULL, /* Not used under Xen. */
33 .con_out_handle = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
34 .con_out = NULL, /* 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
xen_efi_probe(void)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 xen_efi_runtime_setup();
61
62 efi_systab_xen.tables = info->cfg.addr;
63 efi_systab_xen.nr_tables = info->cfg.nent;
64
65 op.cmd = XENPF_firmware_info;
66 op.u.firmware_info.type = XEN_FW_EFI_INFO;
67 op.u.firmware_info.index = XEN_FW_EFI_VENDOR;
68 info->vendor.bufsz = sizeof(vendor);
69 set_xen_guest_handle(info->vendor.name, vendor);
70
71 if (HYPERVISOR_platform_op(&op) == 0) {
72 efi_systab_xen.fw_vendor = __pa_symbol(vendor);
73 efi_systab_xen.fw_revision = info->vendor.revision;
74 } else
75 efi_systab_xen.fw_vendor = __pa_symbol(L"UNKNOWN");
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_VERSION;
80
81 if (HYPERVISOR_platform_op(&op) == 0)
82 efi_systab_xen.hdr.revision = info->version;
83
84 op.cmd = XENPF_firmware_info;
85 op.u.firmware_info.type = XEN_FW_EFI_INFO;
86 op.u.firmware_info.index = XEN_FW_EFI_RT_VERSION;
87
88 if (HYPERVISOR_platform_op(&op) == 0)
89 efi.runtime_version = info->version;
90
91 return &efi_systab_xen;
92 }
93
94 /*
95 * Determine whether we're in secure boot mode.
96 *
97 * Please keep the logic in sync with
98 * drivers/firmware/efi/libstub/secureboot.c:efi_get_secureboot().
99 */
xen_efi_get_secureboot(void)100 static enum efi_secureboot_mode xen_efi_get_secureboot(void)
101 {
102 static efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
103 static efi_guid_t shim_guid = EFI_SHIM_LOCK_GUID;
104 efi_status_t status;
105 u8 moksbstate, secboot, setupmode;
106 unsigned long size;
107
108 size = sizeof(secboot);
109 status = efi.get_variable(L"SecureBoot", &efi_variable_guid,
110 NULL, &size, &secboot);
111
112 if (status == EFI_NOT_FOUND)
113 return efi_secureboot_mode_disabled;
114
115 if (status != EFI_SUCCESS)
116 goto out_efi_err;
117
118 size = sizeof(setupmode);
119 status = efi.get_variable(L"SetupMode", &efi_variable_guid,
120 NULL, &size, &setupmode);
121
122 if (status != EFI_SUCCESS)
123 goto out_efi_err;
124
125 if (secboot == 0 || setupmode == 1)
126 return efi_secureboot_mode_disabled;
127
128 /* See if a user has put the shim into insecure mode. */
129 size = sizeof(moksbstate);
130 status = efi.get_variable(L"MokSBStateRT", &shim_guid,
131 NULL, &size, &moksbstate);
132
133 /* If it fails, we don't care why. Default to secure. */
134 if (status != EFI_SUCCESS)
135 goto secure_boot_enabled;
136
137 if (moksbstate == 1)
138 return efi_secureboot_mode_disabled;
139
140 secure_boot_enabled:
141 pr_info("UEFI Secure Boot is enabled.\n");
142 return efi_secureboot_mode_enabled;
143
144 out_efi_err:
145 pr_err("Could not determine UEFI Secure Boot status.\n");
146 return efi_secureboot_mode_unknown;
147 }
148
xen_efi_init(struct boot_params * boot_params)149 void __init xen_efi_init(struct boot_params *boot_params)
150 {
151 efi_system_table_t *efi_systab_xen;
152
153 efi_systab_xen = xen_efi_probe();
154
155 if (efi_systab_xen == NULL)
156 return;
157
158 strncpy((char *)&boot_params->efi_info.efi_loader_signature, "Xen",
159 sizeof(boot_params->efi_info.efi_loader_signature));
160 boot_params->efi_info.efi_systab = (__u32)__pa(efi_systab_xen);
161 boot_params->efi_info.efi_systab_hi = (__u32)(__pa(efi_systab_xen) >> 32);
162
163 boot_params->secure_boot = xen_efi_get_secureboot();
164
165 set_bit(EFI_BOOT, &efi.flags);
166 set_bit(EFI_PARAVIRT, &efi.flags);
167 set_bit(EFI_64BIT, &efi.flags);
168 }
169