[PATCH v2 02/12] mm: Introduce a function to check for virtualization protection features

[Tom Lendacky]

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 <jroedel at suse.de>
Co-developed-by: Andi Kleen <ak at linux.intel.com>
Signed-off-by: Andi Kleen <ak at linux.intel.com>
Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy at linux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy at linux.intel.com>
Signed-off-by: Tom Lendacky <thomas.lendacky at 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 at amd.com>
+ */
+
+#ifndef _PROTECTED_GUEST_H
+#define _PROTECTED_GUEST_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+#include <linux/stddef.h>
+
+#define PATTR_MEM_ENCRYPT		0	/* Encrypted memory */
+#define PATTR_HOST_MEM_ENCRYPT		1	/* Host encrypted memory */
+#define PATTR_GUEST_MEM_ENCRYPT		2	/* Guest encrypted memory */
+#define PATTR_GUEST_PROT_STATE		3	/* Guest encrypted state */
+
+#ifdef CONFIG_ARCH_HAS_PROTECTED_GUEST
+
+#include <asm/protected_guest.h>
+
+#else	/* !CONFIG_ARCH_HAS_PROTECTED_GUEST */
+
+static inline bool prot_guest_has(unsigned int attr) { return false; }
+
+#endif	/* CONFIG_ARCH_HAS_PROTECTED_GUEST */
+
+#endif	/* __ASSEMBLY__ */
+
+#endif	/* _PROTECTED_GUEST_H */
-- 
2.32.0