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Date: Tue, 19 Dec 2017 19:09:56 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>
cc: LKML <linux-kernel@vger.kernel.org>, x86@kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andy Lutomirsky <luto@kernel.org>, Dave Hansen <dave.hansen@intel.com>,
        Borislav Petkov <bpetkov@suse.de>,
        Greg KH <gregkh@linuxfoundation.org>, keescook@google.com,
        hughd@google.com, Brian Gerst <brgerst@gmail.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Denys Vlasenko <dvlasenk@redhat.com>, Rik van Riel <riel@redhat.com>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Juergen Gross <jgross@suse.com>,
        David Laight <David.Laight@aculab.com>,
        Eduardo Valentin <eduval@amazon.com>, aliguori@amazon.com,
        Will Deacon <will.deacon@arm.com>, daniel.gruss@iaik.tugraz.at,
        Kees Cook <keescook@chromium.org>, Borislav Petkov <bp@alien8.de>,
        "Kirill A. Shutemov" <kirill@shutemov.name>
Subject: Re: [patch V163 38/51] x86/mm/64: Make a full PGD-entry size hole
 in the memory map
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References: <20171218114215.239543034@linutronix.de> <20171218115256.731524766@linutronix.de> <20171218132727.43umqlu4hirgwhlf@hirez.programming.kicks-ass.net>
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On Mon, 18 Dec 2017, Peter Zijlstra wrote:

> On Mon, Dec 18, 2017 at 12:42:53PM +0100, Thomas Gleixner wrote:
> > From: Andy Lutomirski <luto@kernel.org>
> > 
> > Shrink vmalloc space from 16384TiB to 12800TiB to enlarge the hole starting
> > at 0xff90000000000000 to be a full PGD entry.
> > 
> > A subsequent patch will use this hole for the pagetable isolation LDT
> > alias.
> 
> The below patch only changes 5L things, what about 4L ?

I fear I've lost a hunk somewhere on the road ....

> > ---
> >  Documentation/x86/x86_64/mm.txt         |    4 ++--
> >  arch/x86/include/asm/pgtable_64_types.h |    4 ++--
> >  2 files changed, 4 insertions(+), 4 deletions(-)
> > 
> > --- a/Documentation/x86/x86_64/mm.txt
> > +++ b/Documentation/x86/x86_64/mm.txt
> > @@ -28,8 +28,8 @@ ffffffffffe00000 - ffffffffffffffff (=2
> >  hole caused by [56:63] sign extension
> >  ff00000000000000 - ff0fffffffffffff (=52 bits) guard hole, reserved for hypervisor
> >  ff10000000000000 - ff8fffffffffffff (=55 bits) direct mapping of all phys. memory
> > -ff90000000000000 - ff91ffffffffffff (=49 bits) hole
> > -ff92000000000000 - ffd1ffffffffffff (=54 bits) vmalloc/ioremap space
> > +ff90000000000000 - ff9fffffffffffff (=52 bits) hole
> > +ffa0000000000000 - ffd1ffffffffffff (=54 bits) vmalloc/ioremap space (12800 TB)
> >  ffd2000000000000 - ffd3ffffffffffff (=49 bits) hole
> >  ffd4000000000000 - ffd5ffffffffffff (=49 bits) virtual memory map (512TB)
> >  ... unused hole ...
> > --- a/arch/x86/include/asm/pgtable_64_types.h
> > +++ b/arch/x86/include/asm/pgtable_64_types.h
> > @@ -78,8 +78,8 @@ typedef struct { pteval_t pte; } pte_t;
> >  /* See Documentation/x86/x86_64/mm.txt for a description of the memory map. */
> >  #define MAXMEM		_AC(__AC(1, UL) << MAX_PHYSMEM_BITS, UL)
> >  #ifdef CONFIG_X86_5LEVEL
> > -#define VMALLOC_SIZE_TB _AC(16384, UL)
> > -#define __VMALLOC_BASE	_AC(0xff92000000000000, UL)
> > +#define VMALLOC_SIZE_TB _AC(12800, UL)
> > +#define __VMALLOC_BASE	_AC(0xffa0000000000000, UL)
> >  #define __VMEMMAP_BASE	_AC(0xffd4000000000000, UL)
> >  #else
> >  #define VMALLOC_SIZE_TB	_AC(32, UL)
> > 
> > 
>