Quelle  mshyperv.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0

/*
 * Core routines for interacting with Microsoft's Hyper-V hypervisor,
 * including hypervisor initialization.
 *
 * Copyright (C) 2021, Microsoft, Inc.
 *
 * Author : Michael Kelley <mikelley@microsoft.com>
 */

#include <linux/types.h>
#include <linux/acpi.h>
#include <linux/export.h>
#include <linux/errno.h>
#include <linux/version.h>
#include <linux/cpuhotplug.h>
#include <asm/mshyperv.h>

static bool hyperv_initialized;

int hv_get_hypervisor_version(union hv_hypervisor_version_info *info)
{
 hv_get_vpreg_128(HV_REGISTER_HYPERVISOR_VERSION,
    (struct hv_get_vp_registers_output *)info);

 return 0;
}
EXPORT_SYMBOL_GPL(hv_get_hypervisor_version);

#ifdef CONFIG_ACPI

static bool __init hyperv_detect_via_acpi(void)
{
 if (acpi_disabled)
  return false;
 /*
 * Hypervisor ID is only available in ACPI v6+, and the
 * structure layout was extended in v6 to accommodate that
 * new field.
 *
 * At the very minimum, this check makes sure not to read
 * past the FADT structure.
 *
 * It is also needed to catch running in some unknown
 * non-Hyper-V environment that has ACPI 5.x or less.
 * In such a case, it can't be Hyper-V.
 */
 if (acpi_gbl_FADT.header.revision < 6)
  return false;
 return strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8) == 0;
}

#else

static bool __init hyperv_detect_via_acpi(void)
{
 return false;
}

#endif

static bool __init hyperv_detect_via_smccc(void)
{
 uuid_t hyperv_uuid = UUID_INIT(
  0x58ba324d, 0x6447, 0x24cd,
  0x75, 0x6c, 0xef, 0x8e,
  0x24, 0x70, 0x59, 0x16);

 return arm_smccc_hypervisor_has_uuid(&hyperv_uuid);
}

static int __init hyperv_init(void)
{
 struct hv_get_vp_registers_output result;
 u64 guest_id;
 int ret;

 /*
 * Allow for a kernel built with CONFIG_HYPERV to be running in
 * a non-Hyper-V environment.
 *
 * In such cases, do nothing and return success.
 */
 if (!hyperv_detect_via_acpi() && !hyperv_detect_via_smccc())
  return 0;

 /* Setup the guest ID */
 guest_id = hv_generate_guest_id(LINUX_VERSION_CODE);
 hv_set_vpreg(HV_REGISTER_GUEST_OS_ID, guest_id);

 /* Get the features and hints from Hyper-V */
 hv_get_vpreg_128(HV_REGISTER_PRIVILEGES_AND_FEATURES_INFO, &result);
 ms_hyperv.features = result.as32.a;
 ms_hyperv.priv_high = result.as32.b;
 ms_hyperv.misc_features = result.as32.c;

 hv_get_vpreg_128(HV_REGISTER_FEATURES_INFO, &result);
 ms_hyperv.hints = result.as32.a;

 pr_info("Hyper-V: privilege flags low 0x%x, high 0x%x, hints 0x%x, misc 0x%x\n",
  ms_hyperv.features, ms_hyperv.priv_high, ms_hyperv.hints,
  ms_hyperv.misc_features);

 hv_identify_partition_type();

 ret = hv_common_init();
 if (ret)
  return ret;

 ret = cpuhp_setup_state(CPUHP_AP_HYPERV_ONLINE, "arm64/hyperv_init:online",
    hv_common_cpu_init, hv_common_cpu_die);
 if (ret < 0) {
  hv_common_free();
  return ret;
 }

 if (ms_hyperv.priv_high & HV_ACCESS_PARTITION_ID)
  hv_get_partition_id();
 ms_hyperv.vtl = get_vtl();
 if (ms_hyperv.vtl > 0) /* non default VTL */
  pr_info("Linux runs in Hyper-V Virtual Trust Level %d\n", ms_hyperv.vtl);

 ms_hyperv_late_init();

 hyperv_initialized = true;
 return 0;
}

early_initcall(hyperv_init);

bool hv_is_hyperv_initialized(void)
{
 return hyperv_initialized;
}
EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);