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: Roman Kisel <romank@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/hyperv/mshyperv.c | 43 +++++++++++++++++++++++++++----
arch/arm64/include/asm/mshyperv.h | 5 ++++
2 files changed, 43 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
index fc49949b7df6..fe6185bf3bf2 100644
--- a/arch/arm64/hyperv/mshyperv.c
+++ b/arch/arm64/hyperv/mshyperv.c
@@ -27,6 +27,36 @@ int hv_get_hypervisor_version(union hv_hypervisor_version_info *info)
return 0;
}
+static bool hyperv_detect_via_acpi(void)
+{
+ if (acpi_disabled)
+ return false;
+#if IS_ENABLED(CONFIG_ACPI)
+ /* Hypervisor ID is only available in ACPI v6+. */
+ if (acpi_gbl_FADT.header.revision < 6)
+ return false;
+ return strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8) == 0;
+#else
+ return false;
+#endif
+}
+
+static bool hyperv_detect_via_smccc(void)
+{
+ struct arm_smccc_res res = {};
+
+ if (arm_smccc_1_1_get_conduit() != SMCCC_CONDUIT_HVC)
+ return false;
+ arm_smccc_1_1_hvc(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, &res);
+ if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
+ return false;
+
+ return res.a0 == ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_0 &&
+ res.a1 == ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_1 &&
+ res.a2 == ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_2 &&
+ res.a3 == ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_3;
+}
+
static int __init hyperv_init(void)
{
struct hv_get_vp_registers_output result;
@@ -35,13 +65,11 @@ 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 */
@@ -72,6 +100,11 @@ static int __init hyperv_init(void)
return ret;
}
+ ms_hyperv.vtl = get_vtl();
+ /* Report if non-default VTL */
+ if (ms_hyperv.vtl > 0)
+ pr_info("Linux runs in Hyper-V Virtual Trust Level\n");
+
ms_hyperv_late_init();
hyperv_initialized = true;
diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
index 2e2f83bafcfb..a6d7eb9e167b 100644
--- a/arch/arm64/include/asm/mshyperv.h
+++ b/arch/arm64/include/asm/mshyperv.h
@@ -50,4 +50,9 @@ static inline u64 hv_get_msr(unsigned int reg)
#include <asm-generic/mshyperv.h>
+#define ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_0 0x4d32ba58U
+#define ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_1 0xcd244764U
+#define ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_2 0x8eef6c75U
+#define ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_3 0x16597024U
+
#endif
--
2.43.0
