mshyperv.c

  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}
 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);