On 06/12/2018 07:39 AM, Kirill A. Shutemov wrote:
> 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.

Isn't it really *the* direct mapping primarily?  We make all of them
larger, but the direct mapping is impacted too.  This makes it sound
like it applies only to the MKTME mappings.

> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 4fa2cf807321..d013495bb4ae 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1513,6 +1513,23 @@ 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 Intel processor that has support of the feature.

"requires an Intel processor"...

> +       Multikey Total Memory Encryption (MKTME) is a technology that allows
> +       transparent memory encryption in upcoming Intel platforms.

"in an upcoming"

> +       MKTME is built on top of TME. TME allows encryption of the entirety
> +       of system memory using a single key. MKTME allows to have multiple

"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"
> @@ -2189,7 +2206,7 @@ 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
> 

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