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

[Tom Lendacky]

On 4/27/2017 11:12 AM, Borislav Petkov wrote:
> 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...?

I masked it out here based on a previous comment from Dave Hansen:

  http://marc.info/?l=linux-kernel&m=148778719826905&w=2

I could move the __sme_clr into the individual defines of:

PHYSICAL_PAGE_MASK, PHYSICAL_PMD_PAGE_MASK and PHYSICAL_PUD_PAGE_MASK

Either way works for me.

Thanks,
Tom

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