[RFC PATCH v1 03/18] x86: Secure Memory Encryption (SME) support

Tom Lendacky
2016-04-26T22:45:43Z

Provide support for Secure Memory Encryption (SME). This initial support
defines the memory encryption mask as a variable for quick access and an
accessor for retrieving the number of physical addressing bits lost if
SME is enabled.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
arch/x86/include/asm/mem_encrypt.h | 37 ++++++++++++++++++++++++++++++++++++
arch/x86/kernel/Makefile | 2 ++
arch/x86/kernel/mem_encrypt.S | 29 ++++++++++++++++++++++++++++
arch/x86/kernel/x8664_ksyms_64.c | 6 ++++++
4 files changed, 74 insertions(+)
create mode 100644 arch/x86/include/asm/mem_encrypt.h
create mode 100644 arch/x86/kernel/mem_encrypt.S

diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
new file mode 100644
index 0000000..747fc52
--- /dev/null
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -0,0 +1,37 @@
+/*
+ * 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;
+
+u8 sme_get_me_loss(void);
+
+#else /* !CONFIG_AMD_MEM_ENCRYPT */
+
+#define sme_me_mask 0UL
+
+static inline u8 sme_get_me_loss(void)
+{
+ return 0;
+}
+
+#endif /* CONFIG_AMD_MEM_ENCRYPT */
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __X86_MEM_ENCRYPT_H__ */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 9abf855..11536d9 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -126,6 +126,8 @@ obj-$(CONFIG_EFI) += sysfb_efi.o
obj-$(CONFIG_PERF_EVENTS) += perf_regs.o
obj-$(CONFIG_TRACING) += tracepoint.o

+obj-y += mem_encrypt.o
+
###
# 64 bit specific files
ifeq ($(CONFIG_X86_64),y)
diff --git a/arch/x86/kernel/mem_encrypt.S b/arch/x86/kernel/mem_encrypt.S
new file mode 100644
index 0000000..ef7f325
--- /dev/null
+++ b/arch/x86/kernel/mem_encrypt.S
@@ -0,0 +1,29 @@
+/*
+ * 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>
+
+ .text
+ .code64
+ENTRY(sme_get_me_loss)
+ xor %rax, %rax
+ mov sme_me_loss(%rip), %al
+ ret
+ENDPROC(sme_get_me_loss)
+
+ .data
+ .align 16
+ENTRY(sme_me_mask)
+ .quad 0x0000000000000000
+sme_me_loss:
+ .byte 0x00
+ .align 8
diff --git a/arch/x86/kernel/x8664_ksyms_64.c b/arch/x86/kernel/x8664_ksyms_64.c
index cd05942..72cb689 100644
--- a/arch/x86/kernel/x8664_ksyms_64.c
+++ b/arch/x86/kernel/x8664_ksyms_64.c
@@ -11,6 +11,7 @@
#include <asm/uaccess.h>
#include <asm/desc.h>
#include <asm/ftrace.h>
+#include <asm/mem_encrypt.h>

#ifdef CONFIG_FUNCTION_TRACER
/* mcount and __fentry__ are defined in assembly */
@@ -79,3 +80,8 @@ EXPORT_SYMBOL(native_load_gs_index);
EXPORT_SYMBOL(___preempt_schedule);
EXPORT_SYMBOL(___preempt_schedule_notrace);
#endif
+
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+EXPORT_SYMBOL_GPL(sme_me_mask);
+EXPORT_SYMBOL_GPL(sme_get_me_loss);
+#endif