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Subject[RFC PATCH v3 05/20] x86: Add Secure Memory Encryption (SME) support
Date
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 <thomas.lendacky@amd.com>
---
arch/x86/Kconfig | 9 +++++++++
arch/x86/include/asm/mem_encrypt.h | 30 ++++++++++++++++++++++++++++++
arch/x86/mm/Makefile | 1 +
arch/x86/mm/mem_encrypt.c | 21 +++++++++++++++++++++
include/linux/mem_encrypt.h | 30 ++++++++++++++++++++++++++++++
5 files changed, 91 insertions(+)
create mode 100644 arch/x86/include/asm/mem_encrypt.h
create mode 100644 arch/x86/mm/mem_encrypt.c
create mode 100644 include/linux/mem_encrypt.h

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 9b2d50a..cc57bc0 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1368,6 +1368,15 @@ config X86_DIRECT_GBPAGES
supports them), so don't confuse the user by printing
that we have them enabled.

+config AMD_MEM_ENCRYPT
+ bool "AMD Secure Memory Encryption support"
+ depends on X86_64 && CPU_SUP_AMD
+ ---help---
+ Say yes to enable the encryption of system memory. This requires
+ an AMD processor that supports Secure Memory Encryption (SME).
+ The encryption of system memory is disabled by default but can be
+ enabled with the mem_encrypt=on command line option.
+
# Common NUMA Features
config NUMA
bool "Numa Memory Allocation and Scheduler Support"
diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
new file mode 100644
index 0000000..a105796
--- /dev/null
+++ b/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 <thomas.lendacky@amd.com>
+ *
+ * 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__ */
diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index 96d2b84..44d4d21 100644
--- a/arch/x86/mm/Makefile
+++ b/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
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
new file mode 100644
index 0000000..1ed75a4
--- /dev/null
+++ b/arch/x86/mm/mem_encrypt.c
@@ -0,0 +1,21 @@
+/*
+ * AMD Memory Encryption Support
+ *
+ * Copyright (C) 2016 Advanced Micro Devices, Inc.
+ *
+ * Author: Tom Lendacky <thomas.lendacky@amd.com>
+ *
+ * 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_me_mask is set early in the boot process it 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);
diff --git a/include/linux/mem_encrypt.h b/include/linux/mem_encrypt.h
new file mode 100644
index 0000000..9fed068
--- /dev/null
+++ b/include/linux/mem_encrypt.h
@@ -0,0 +1,30 @@
+/*
+ * AMD Memory Encryption Support
+ *
+ * Copyright (C) 2016 Advanced Micro Devices, Inc.
+ *
+ * Author: Tom Lendacky <thomas.lendacky@amd.com>
+ *
+ * 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_AMD_MEM_ENCRYPT
+
+#include <asm/mem_encrypt.h>
+
+#else /* !CONFIG_AMD_MEM_ENCRYPT */
+
+#define sme_me_mask 0UL
+
+#endif /* CONFIG_AMD_MEM_ENCRYPT */
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __MEM_ENCRYPT_H__ */
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