Commit 36ebd328 authored by Roman Kisel's avatar Roman Kisel Committed by Wei Liu
Browse files

arm64: hyperv: Use SMCCC to detect hypervisor presence 



The arm64 Hyper-V startup path relies on ACPI to detect
running under a Hyper-V compatible hypervisor. That
doesn't work on non-ACPI systems.

Hoist the ACPI detection logic into a separate function. Then
use the vendor-specific hypervisor service call (implemented
recently in Hyper-V) via SMCCC in the non-ACPI case.

Signed-off-by: default avatarRoman Kisel <romank@linux.microsoft.com>
Reviewed-by: default avatarMichael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/20250428210742.435282-3-romank@linux.microsoft.com


Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
Message-ID: <20250428210742.435282-3-romank@linux.microsoft.com>
parent 13423063

arch/arm64/hyperv/mshyperv.c

+45 −5
Original line number Diff line number Diff line
@@ -28,6 +28,48 @@ int hv_get_hypervisor_version(union hv_hypervisor_version_info *info) 
}

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;
@@ -36,13 +78,11 @@ static int __init hyperv_init(void) 


	/*

	 * Allow for a kernel built with CONFIG_HYPERV to be running in

	 * a non-Hyper-V environment, including on DT instead of ACPI.

	 * a non-Hyper-V environment.

	 *

	 * In such cases, do nothing and return success.

	 */

	if (acpi_disabled)

		return 0;



	if (strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8))

	if (!hyperv_detect_via_acpi() && !hyperv_detect_via_smccc())

		return 0;



	/* Setup the guest ID */