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1// SPDX-License-Identifier: GPL-2.0
2
3/*
4 * Core routines for interacting with Microsoft's Hyper-V hypervisor,
5 * including hypervisor initialization.
6 *
7 * Copyright (C) 2021, Microsoft, Inc.
8 *
9 * Author : Michael Kelley <[email protected]>
10 */
11
12#include <linux/types.h>
13#include <linux/acpi.h>
14#include <linux/export.h>
15#include <linux/errno.h>
16#include <linux/version.h>
17#include <linux/cpuhotplug.h>
18#include <asm/mshyperv.h>
19
20static bool hyperv_initialized;
21
22int hv_get_hypervisor_version(union hv_hypervisor_version_info *info)
23{
24 hv_get_vpreg_128(HV_REGISTER_HYPERVISOR_VERSION,
25 (struct hv_get_vp_registers_output *)info);
26
27 return 0;
28}
29EXPORT_SYMBOL_GPL(hv_get_hypervisor_version);
30
31#ifdef CONFIG_ACPI
32
33static bool __init hyperv_detect_via_acpi(void)
34{
35 if (acpi_disabled)
36 return false;
37 /*
38 * Hypervisor ID is only available in ACPI v6+, and the
39 * structure layout was extended in v6 to accommodate that
40 * new field.
41 *
42 * At the very minimum, this check makes sure not to read
43 * past the FADT structure.
44 *
45 * It is also needed to catch running in some unknown
46 * non-Hyper-V environment that has ACPI 5.x or less.
47 * In such a case, it can't be Hyper-V.
48 */
49 if (acpi_gbl_FADT.header.revision < 6)
50 return false;
51 return strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8) == 0;
52}
53
54#else
55
56static bool __init hyperv_detect_via_acpi(void)
57{
58 return false;
59}
60
61#endif
62
63static bool __init hyperv_detect_via_smccc(void)
64{
65 uuid_t hyperv_uuid = UUID_INIT(
66 0x58ba324d, 0x6447, 0x24cd,
67 0x75, 0x6c, 0xef, 0x8e,
68 0x24, 0x70, 0x59, 0x16);
69
70 return arm_smccc_hypervisor_has_uuid(&hyperv_uuid);
71}
72
73static int __init hyperv_init(void)
74{
75 struct hv_get_vp_registers_output result;
76 u64 guest_id;
77 int ret;
78
79 /*
80 * Allow for a kernel built with CONFIG_HYPERV to be running in
81 * a non-Hyper-V environment.
82 *
83 * In such cases, do nothing and return success.
84 */
85 if (!hyperv_detect_via_acpi() && !hyperv_detect_via_smccc())
86 return 0;
87
88 /* Setup the guest ID */
89 guest_id = hv_generate_guest_id(LINUX_VERSION_CODE);
90 hv_set_vpreg(HV_REGISTER_GUEST_OS_ID, guest_id);
91
92 /* Get the features and hints from Hyper-V */
93 hv_get_vpreg_128(HV_REGISTER_PRIVILEGES_AND_FEATURES_INFO, &result);
94 ms_hyperv.features = result.as32.a;
95 ms_hyperv.priv_high = result.as32.b;
96 ms_hyperv.misc_features = result.as32.c;
97
98 hv_get_vpreg_128(HV_REGISTER_FEATURES_INFO, &result);
99 ms_hyperv.hints = result.as32.a;
100
101 pr_info("Hyper-V: privilege flags low 0x%x, high 0x%x, hints 0x%x, misc 0x%x\n",
102 ms_hyperv.features, ms_hyperv.priv_high, ms_hyperv.hints,
103 ms_hyperv.misc_features);
104
105 hv_identify_partition_type();
106
107 ret = hv_common_init();
108 if (ret)
109 return ret;
110
111 ret = cpuhp_setup_state(CPUHP_AP_HYPERV_ONLINE, "arm64/hyperv_init:online",
112 hv_common_cpu_init, hv_common_cpu_die);
113 if (ret < 0) {
114 hv_common_free();
115 return ret;
116 }
117
118 if (ms_hyperv.priv_high & HV_ACCESS_PARTITION_ID)
119 hv_get_partition_id();
120 ms_hyperv.vtl = get_vtl();
121 if (ms_hyperv.vtl > 0) /* non default VTL */
122 pr_info("Linux runs in Hyper-V Virtual Trust Level %d\n", ms_hyperv.vtl);
123
124 ms_hyperv_late_init();
125
126 hyperv_initialized = true;
127 return 0;
128}
129
130early_initcall(hyperv_init);
131
132bool hv_is_hyperv_initialized(void)
133{
134 return hyperv_initialized;
135}
136EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);