In prep for other protected virtualization technologies, introduce a
generic helper function, prot_guest_has(), that can be used to check
for specific protection attributes, like memory encryption. This is
intended to eliminate having to add multiple technology-specific checks
to the code (e.g. if (sev_active() || tdx_active())).

Reviewed-by: Joerg Roedel <redacted>
Co-developed-by: Andi Kleen <redacted>
Signed-off-by: Andi Kleen <redacted>
Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 arch/Kconfig                    |  3 +++
 include/linux/protected_guest.h | 35 +++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)
 create mode 100644 include/linux/protected_guest.h

diff --git a/arch/Kconfig b/arch/Kconfig
index 98db63496bab..bd4f60c581f1 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig

@@ -1231,6 +1231,9 @@ config RELR
 config ARCH_HAS_MEM_ENCRYPT
 	bool
 
+config ARCH_HAS_PROTECTED_GUEST
+	bool
+
 config HAVE_SPARSE_SYSCALL_NR
        bool
        help

diff --git a/include/linux/protected_guest.h b/include/linux/protected_guest.h
new file mode 100644
index 000000000000..43d4dde94793
--- /dev/null
+++ b/include/linux/protected_guest.h

@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Protected Guest (and Host) Capability checks
+ *
+ * Copyright (C) 2021 Advanced Micro Devices, Inc.
+ *
+ * Author: Tom Lendacky <thomas.lendacky@amd.com>
+ */
+
+#ifndef _PROTECTED_GUEST_H
+#define _PROTECTED_GUEST_H
+
+#ifndef __ASSEMBLY__