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From:   Saurabh Sengar <ssengar@linux.microsoft.com>
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Subject: [PATCH v4 4/5] Drivers: hv: Kconfig: Add HYPERV_VTL_MODE
Date:   Tue,  4 Apr 2023 02:01:03 -0700
Message-Id: <1680598864-16981-5-git-send-email-ssengar@linux.microsoft.com>
In-Reply-To: <1680598864-16981-1-git-send-email-ssengar@linux.microsoft.com>
References: <1680598864-16981-1-git-send-email-ssengar@linux.microsoft.com>
Precedence: bulk

Add HYPERV_VTL_MODE Kconfig flag for VTL mode.

Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
---
 drivers/hv/Kconfig | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
index 0747a8f1fcee..511f2e012c59 100644
--- a/drivers/hv/Kconfig
+++ b/drivers/hv/Kconfig
@@ -13,6 +13,30 @@ config HYPERV
 	  Select this option to run Linux as a Hyper-V client operating
 	  system.
 
+config HYPERV_VTL_MODE
+	bool "Enable Linux to boot in VTL context"
+	depends on X86_64 && HYPERV
+	default n
+	help
+	  Virtual Secure Mode (VSM) is a set of hypervisor capabilities and
+	  enlightenments offered to host and guest partitions which enables
+	  the creation and management of new security boundaries within
+	  operating system software.
+
+	  VSM achieves and maintains isolation through Virtual Trust Levels
+	  (VTLs). Virtual Trust Levels are hierarchical, with higher levels
+	  being more privileged than lower levels. VTL0 is the least privileged
+	  level, and currently only other level supported is VTL2.
+
+	  Select this option to build a Linux kernel to run at a VTL other than
+	  the normal VTL0, which currently is only VTL2.  This option
+	  initializes the x86 platform for VTL2, and adds the ability to boot
+	  secondary CPUs directly into 64-bit context as required for VTLs other
+	  than 0.  A kernel built with this option must run at VTL2, and will
+	  not run as a normal guest.
+
+	  If unsure, say N
+
 config HYPERV_TIMER
 	def_bool HYPERV && X86
 
-- 
2.34.1