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 <mikelley@microsoft.com>
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}
29
30static int __init hyperv_init(void)
31{
32 struct hv_get_vp_registers_output result;
33 u64 guest_id;
34 int ret;
35
36 /*
37 * Allow for a kernel built with CONFIG_HYPERV to be running in
38 * a non-Hyper-V environment, including on DT instead of ACPI.
39 * In such cases, do nothing and return success.
40 */
41 if (acpi_disabled)
42 return 0;
43
44 if (strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8))
45 return 0;
46
47 /* Setup the guest ID */
48 guest_id = hv_generate_guest_id(LINUX_VERSION_CODE);
49 hv_set_vpreg(HV_REGISTER_GUEST_OS_ID, guest_id);
50
51 /* Get the features and hints from Hyper-V */
52 hv_get_vpreg_128(HV_REGISTER_FEATURES, &result);
53 ms_hyperv.features = result.as32.a;
54 ms_hyperv.priv_high = result.as32.b;
55 ms_hyperv.misc_features = result.as32.c;
56
57 hv_get_vpreg_128(HV_REGISTER_ENLIGHTENMENTS, &result);
58 ms_hyperv.hints = result.as32.a;
59
60 pr_info("Hyper-V: privilege flags low 0x%x, high 0x%x, hints 0x%x, misc 0x%x\n",
61 ms_hyperv.features, ms_hyperv.priv_high, ms_hyperv.hints,
62 ms_hyperv.misc_features);
63
64 ret = hv_common_init();
65 if (ret)
66 return ret;
67
68 ret = cpuhp_setup_state(state: CPUHP_AP_HYPERV_ONLINE, name: "arm64/hyperv_init:online",
69 startup: hv_common_cpu_init, teardown: hv_common_cpu_die);
70 if (ret < 0) {
71 hv_common_free();
72 return ret;
73 }
74
75 ms_hyperv_late_init();
76
77 hyperv_initialized = true;
78 return 0;
79}
80
81early_initcall(hyperv_init);
82
83bool hv_is_hyperv_initialized(void)
84{
85 return hyperv_initialized;
86}
87EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);
88

source code of linux/arch/arm64/hyperv/mshyperv.c