x86/mm: Add Secure Memory Encryption (SME) support

Add support for Secure Memory Encryption (SME). This initial support
provides a Kconfig entry to build the SME support into the kernel and
defines the memory encryption mask that will be used in subsequent
patches to mark pages as encrypted.

Signed-off-by: Tom Lendacky <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Reviewed-by: Borislav Petkov <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brijesh Singh <[email protected]>
Cc: Dave Young <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Konrad Rzeszutek Wilk <[email protected]>
Cc: Larry Woodman <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Matt Fleming <[email protected]>
Cc: Michael S. Tsirkin <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Radim Krčmář <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Toshimitsu Kani <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/a6c34d16caaed3bc3e2d6f0987554275bd291554.1500319216.git.thomas.lendacky@amd.com
Signed-off-by: Ingo Molnar <[email protected]>

Author: tlendacky

arch/x86/Kconfig

@@ -1415,6 +1415,31 @@ config X86_DIRECT_GBPAGES
 	  supports them), so don't confuse the user by printing
 	  that we have them enabled.
 
+config ARCH_HAS_MEM_ENCRYPT
+	def_bool y
+
+config AMD_MEM_ENCRYPT
+	bool "AMD Secure Memory Encryption (SME) support"
+	depends on X86_64 && CPU_SUP_AMD
+	---help---
+	  Say yes to enable support for the encryption of system memory.
+	  This requires an AMD processor that supports Secure Memory
+	  Encryption (SME).
+
+config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
+	bool "Activate AMD Secure Memory Encryption (SME) by default"
+	default y
+	depends on AMD_MEM_ENCRYPT
+	---help---
+	  Say yes to have system memory encrypted by default if running on
+	  an AMD processor that supports Secure Memory Encryption (SME).
+
+	  If set to Y, then the encryption of system memory can be
+	  deactivated with the mem_encrypt=off command line option.
+
+	  If set to N, then the encryption of system memory can be
+	  activated with the mem_encrypt=on command line option.
+
 # Common NUMA Features
 config NUMA
 	bool "Numa Memory Allocation and Scheduler Support"

arch/x86/include/asm/mem_encrypt.h

@@ -0,0 +1,30 @@
+/*
+ * AMD Memory Encryption Support
+ *
+ * Copyright (C) 2016 Advanced Micro Devices, Inc.
+ *
+ * Author: Tom Lendacky <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __X86_MEM_ENCRYPT_H__
+#define __X86_MEM_ENCRYPT_H__
+
+#ifndef __ASSEMBLY__
+
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+
+extern unsigned long sme_me_mask;
+
+#else	/* !CONFIG_AMD_MEM_ENCRYPT */
+
+#define sme_me_mask	0UL
+
+#endif	/* CONFIG_AMD_MEM_ENCRYPT */
+
+#endif	/* __ASSEMBLY__ */
+
+#endif	/* __X86_MEM_ENCRYPT_H__ */

arch/x86/mm/Makefile

@@ -39,3 +39,4 @@ obj-$(CONFIG_X86_INTEL_MPX)	+= mpx.o
 obj-$(CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) += pkeys.o
 obj-$(CONFIG_RANDOMIZE_MEMORY) += kaslr.o
 
+obj-$(CONFIG_AMD_MEM_ENCRYPT)	+= mem_encrypt.o

arch/x86/mm/mem_encrypt.c

@@ -0,0 +1,21 @@
+/*
+ * AMD Memory Encryption Support
+ *
+ * Copyright (C) 2016 Advanced Micro Devices, Inc.
+ *
+ * Author: Tom Lendacky <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/linkage.h>
+
+/*
+ * Since SME related variables are set early in the boot process they must
+ * reside in the .data section so as not to be zeroed out when the .bss
+ * section is later cleared.
+ */
+unsigned long sme_me_mask __section(.data) = 0;
+EXPORT_SYMBOL_GPL(sme_me_mask);

include/linux/mem_encrypt.h

@@ -0,0 +1,35 @@
+/*
+ * AMD Memory Encryption Support
+ *
+ * Copyright (C) 2016 Advanced Micro Devices, Inc.
+ *
+ * Author: Tom Lendacky <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __MEM_ENCRYPT_H__
+#define __MEM_ENCRYPT_H__
+
+#ifndef __ASSEMBLY__
+
+#ifdef CONFIG_ARCH_HAS_MEM_ENCRYPT
+
+#include <asm/mem_encrypt.h>
+
+#else	/* !CONFIG_ARCH_HAS_MEM_ENCRYPT */
+
+#define sme_me_mask	0UL
+
+#endif	/* CONFIG_ARCH_HAS_MEM_ENCRYPT */
+
+static inline bool sme_active(void)
+{
+	return !!sme_me_mask;
+}
+
+#endif	/* __ASSEMBLY__ */
+
+#endif	/* __MEM_ENCRYPT_H__ */