Re: [PATCH v5 09/32] x86/mm: Provide general kernel support for memory encryption

Borislav Petkov
2017-04-27T16:12:39Z

On Tue, Apr 18, 2017 at 04:17:54PM -0500, Tom Lendacky wrote:
> Changes to the existing page table macros will allow the SME support to
> be enabled in a simple fashion with minimal changes to files that use these
> macros. Since the memory encryption mask will now be part of the regular
> pagetable macros, we introduce two new macros (_PAGE_TABLE_NOENC and
> _KERNPG_TABLE_NOENC) to allow for early pagetable creation/initialization
> without the encryption mask before SME becomes active. Two new pgprot()
> macros are defined to allow setting or clearing the page encryption mask.

...

> @@ -55,7 +57,7 @@ static inline void copy_user_page(void *to, void *from, unsigned long vaddr,
> __phys_addr_symbol(__phys_reloc_hide((unsigned long)(x)))
>
> #ifndef __va
> -#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET))
> +#define __va(x) ((void *)(__sme_clr(x) + PAGE_OFFSET))
> #endif
>
> #define __boot_va(x) __va(x)
> diff --git a/arch/x86/include/asm/page_types.h b/arch/x86/include/asm/page_types.h
> index 7bd0099..fead0a5 100644
> --- a/arch/x86/include/asm/page_types.h
> +++ b/arch/x86/include/asm/page_types.h
> @@ -15,7 +15,7 @@
> #define PUD_PAGE_SIZE (_AC(1, UL) << PUD_SHIFT)
> #define PUD_PAGE_MASK (~(PUD_PAGE_SIZE-1))
>
> -#define __PHYSICAL_MASK ((phys_addr_t)((1ULL << __PHYSICAL_MASK_SHIFT) - 1))
> +#define __PHYSICAL_MASK ((phys_addr_t)(__sme_clr((1ULL << __PHYSICAL_MASK_SHIFT) - 1)))

That looks strange: poking SME mask hole into a mask...?

> #define __VIRTUAL_MASK ((1UL << __VIRTUAL_MASK_SHIFT) - 1)
>
> /* Cast *PAGE_MASK to a signed type so that it is sign-extended if

--
Regards/Gruss,
Boris.

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