[PATCH v3 4/7] arm64: hyperv: Boot in a Virtual Trust Level

[Roman Kisel]

To run in the VTL mode, Hyper-V drivers have to know what
VTL the system boots in, and the arm64/hyperv code does not
update the variable that stores the value.

Update the variable to enable the Hyper-V drivers to boot
in the VTL mode and print the VTL the code runs in.

Signed-off-by: Roman Kisel <romank at linux.microsoft.com>
---
 arch/arm64/hyperv/Makefile        |  1 +
 arch/arm64/hyperv/hv_vtl.c        | 13 +++++++++++++
 arch/arm64/hyperv/mshyperv.c      |  4 ++++
 arch/arm64/include/asm/mshyperv.h |  7 +++++++
 4 files changed, 25 insertions(+)
 create mode 100644 arch/arm64/hyperv/hv_vtl.c

diff --git a/arch/arm64/hyperv/Makefile b/arch/arm64/hyperv/Makefile
index 87c31c001da9..9701a837a6e1 100644
--- a/arch/arm64/hyperv/Makefile
+++ b/arch/arm64/hyperv/Makefile
@@ -1,2 +1,3 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-y		:= hv_core.o mshyperv.o
+obj-$(CONFIG_HYPERV_VTL_MODE)	+= hv_vtl.o
diff --git a/arch/arm64/hyperv/hv_vtl.c b/arch/arm64/hyperv/hv_vtl.c
new file mode 100644
index 000000000000..38642b7b6be0
--- /dev/null
+++ b/arch/arm64/hyperv/hv_vtl.c
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024, Microsoft, Inc.
+ *
+ * Author : Roman Kisel <romank at linux.microsoft.com>
+ */
+
+#include <asm/mshyperv.h>
+
+void __init hv_vtl_init_platform(void)
+{
+	pr_info("Linux runs in Hyper-V Virtual Trust Level\n");
+}
diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
index 341f98312667..8fd04d6e4800 100644
--- a/arch/arm64/hyperv/mshyperv.c
+++ b/arch/arm64/hyperv/mshyperv.c
@@ -98,6 +98,10 @@ static int __init hyperv_init(void)
 		return ret;
 	}
 
+	/* Find the VTL */
+	ms_hyperv.vtl = get_vtl();
+	hv_vtl_init_platform();
+
 	ms_hyperv_late_init();
 
 	hyperv_initialized = true;
diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
index a7a3586f7cb1..63d6bb6998fc 100644
--- a/arch/arm64/include/asm/mshyperv.h
+++ b/arch/arm64/include/asm/mshyperv.h
@@ -49,6 +49,13 @@ static inline u64 hv_get_msr(unsigned int reg)
 				ARM_SMCCC_OWNER_VENDOR_HYP,	\
 				HV_SMCCC_FUNC_NUMBER)
 
+#ifdef CONFIG_HYPERV_VTL_MODE
+void __init hv_vtl_init_platform(void);
+int __init hv_vtl_early_init(void);
+#else
+static inline void __init hv_vtl_init_platform(void) {}
+#endif
+
 #include <asm-generic/mshyperv.h>
 
 #define ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_0	0x7948734d
-- 
2.34.1