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
22static int __init hyperv_init(void)
23{
24	struct hv_get_vp_registers_output	result;
25	u32	a, b, c, d;
26	u64	guest_id;
27	int	ret;
28
29	/*
30	 * Allow for a kernel built with CONFIG_HYPERV to be running in
31	 * a non-Hyper-V environment, including on DT instead of ACPI.
32	 * In such cases, do nothing and return success.
33	 */
34	if (acpi_disabled)
35		return 0;
36
37	if (strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8))
38		return 0;
39
40	/* Setup the guest ID */
41	guest_id = hv_generate_guest_id(LINUX_VERSION_CODE);
42	hv_set_vpreg(HV_REGISTER_GUEST_OSID, guest_id);
43
44	/* Get the features and hints from Hyper-V */
45	hv_get_vpreg_128(HV_REGISTER_FEATURES, &result);
46	ms_hyperv.features = result.as32.a;
47	ms_hyperv.priv_high = result.as32.b;
48	ms_hyperv.misc_features = result.as32.c;
49
50	hv_get_vpreg_128(HV_REGISTER_ENLIGHTENMENTS, &result);
51	ms_hyperv.hints = result.as32.a;
52
53	pr_info("Hyper-V: privilege flags low 0x%x, high 0x%x, hints 0x%x, misc 0x%x\n",
54		ms_hyperv.features, ms_hyperv.priv_high, ms_hyperv.hints,
55		ms_hyperv.misc_features);
56
57	/* Get information about the Hyper-V host version */
58	hv_get_vpreg_128(HV_REGISTER_HYPERVISOR_VERSION, &result);
59	a = result.as32.a;
60	b = result.as32.b;
61	c = result.as32.c;
62	d = result.as32.d;
63	pr_info("Hyper-V: Host Build %d.%d.%d.%d-%d-%d\n",
64		b >> 16, b & 0xFFFF, a,	d & 0xFFFFFF, c, d >> 24);
65
66	ret = hv_common_init();
67	if (ret)
68		return ret;
69
70	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "arm64/hyperv_init:online",
71				hv_common_cpu_init, hv_common_cpu_die);
72	if (ret < 0) {
73		hv_common_free();
74		return ret;
75	}
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);