arch/arm64/hyperv/mshyperv.c

Source file repositories/reference/linux-study-clean/arch/arm64/hyperv/mshyperv.c

File Facts

System
Linux kernel
Corpus path
arch/arm64/hyperv/mshyperv.c
Extension
.c
Size
3297 bytes
Lines
137
Domain
Architecture Layer
Bucket
arch/arm64
Inferred role
Architecture Layer: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

// 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);

Annotation

Implementation Notes