linux-kernel - [PATCH v2 4/6] arm64/hyperv: Boot in a Virtual Trust Level

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Date: Tue, 14 May 2024 15:43:51 -0700
From: Roman Kisel <romank@...ux.microsoft.com>
To: arnd@...db.de,
	bhelgaas@...gle.com,
	bp@...en8.de,
	catalin.marinas@....com,
	dave.hansen@...ux.intel.com,
	decui@...rosoft.com,
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	linux-acpi@...r.kernel.org,
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Cc: ssengar@...rosoft.com,
	sunilmut@...rosoft.com,
	vdso@...bites.dev
Subject: [PATCH v2 4/6] arm64/hyperv: Boot in a Virtual Trust Level

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@...ux.microsoft.com>
---
 arch/arm64/hyperv/Makefile        |  1 +
 arch/arm64/hyperv/hv_vtl.c        | 19 +++++++++++++++++++
 arch/arm64/hyperv/mshyperv.c      |  6 ++++++
 arch/arm64/include/asm/mshyperv.h |  8 ++++++++
 arch/x86/hyperv/hv_vtl.c          |  2 +-
 5 files changed, 35 insertions(+), 1 deletion(-)
 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..9b44cc49594c
--- /dev/null
+++ b/arch/arm64/hyperv/hv_vtl.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023, Microsoft, Inc.
+ *
+ * Author : Roman Kisel <romank@...ux.microsoft.com>
+ */
+
+#include <asm/mshyperv.h>
+
+void __init hv_vtl_init_platform(void)
+{
+	pr_info("Linux runs in Hyper-V Virtual Trust Level %d\n", ms_hyperv.vtl);
+}
+
+int __init hv_vtl_early_init(void)
+{
+	return 0;
+}
+early_initcall(hv_vtl_early_init);
diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
index 208a3bcb9686..cbde483b167a 100644
--- a/arch/arm64/hyperv/mshyperv.c
+++ b/arch/arm64/hyperv/mshyperv.c
@@ -96,6 +96,12 @@ static int __init hyperv_init(void)
 		return ret;
 	}
 
+	/* Find the VTL */
+	ms_hyperv.vtl = get_vtl();
+	if (ms_hyperv.vtl > 0) /* non default VTL */
+		hv_vtl_early_init();
+
+	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 a975e1a689dd..4a8ff6be389c 100644
--- a/arch/arm64/include/asm/mshyperv.h
+++ b/arch/arm64/include/asm/mshyperv.h
@@ -49,6 +49,14 @@ 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) {}
+static inline int __init hv_vtl_early_init(void) { return 0; }
+#endif
+
 #include <asm-generic/mshyperv.h>
 
 #endif
diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c
index 92bd5a55f093..ae3105375a12 100644
--- a/arch/x86/hyperv/hv_vtl.c
+++ b/arch/x86/hyperv/hv_vtl.c
@@ -19,7 +19,7 @@ static struct real_mode_header hv_vtl_real_mode_header;
 
 void __init hv_vtl_init_platform(void)
 {
-	pr_info("Linux runs in Hyper-V Virtual Trust Level\n");
+	pr_info("Linux runs in Hyper-V Virtual Trust Level %d\n", ms_hyperv.vtl);
 
 	x86_platform.realmode_reserve = x86_init_noop;
 	x86_platform.realmode_init = x86_init_noop;
-- 
2.45.0