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(CPUHP_AP_HYPERV_ONLINE, "arm64/hyperv_init:online",
69				hv_common_cpu_init, 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);