[PATCHv4 18/18] x86: Introduce CONFIG_X86_INTEL_MKTME

[Kirill A. Shutemov]

Add new config option to enabled/disable Multi-Key Total Memory
Encryption support.

MKTME uses MEMORY_PHYSICAL_PADDING to reserve enough space in per-KeyID
direct mappings for memory hotplug.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
 arch/x86/Kconfig | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index fa5e1ec09247..9a843bd63108 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1523,6 +1523,23 @@ config ARCH_USE_MEMREMAP_PROT
 	def_bool y
 	depends on AMD_MEM_ENCRYPT
 
+config X86_INTEL_MKTME
+	bool "Intel Multi-Key Total Memory Encryption"
+	select DYNAMIC_PHYSICAL_MASK
+	select PAGE_EXTENSION
+	depends on X86_64 && CPU_SUP_INTEL
+	---help---
+	  Say yes to enable support for Multi-Key Total Memory Encryption.
+	  This requires an Intel processor that has support of the feature.
+
+	  Multikey Total Memory Encryption (MKTME) is a technology that allows
+	  transparent memory encryption in and upcoming Intel platforms.
+
+	  MKTME is built on top of TME. TME allows encryption of the entirety
+	  of system memory using a single key. MKTME allows having multiple
+	  encryption domains, each having own key -- different memory pages can
+	  be encrypted with different keys.
+
 # Common NUMA Features
 config NUMA
 	bool "Numa Memory Allocation and Scheduler Support"
@@ -2199,7 +2216,7 @@ config RANDOMIZE_MEMORY
 
 config MEMORY_PHYSICAL_PADDING
 	hex "Physical memory mapping padding" if EXPERT
-	depends on RANDOMIZE_MEMORY
+	depends on RANDOMIZE_MEMORY || X86_INTEL_MKTME
 	default "0xa" if MEMORY_HOTPLUG
 	default "0x0"
 	range 0x1 0x40 if MEMORY_HOTPLUG
-- 
2.18.0