Re: [patch V163 38/51] x86/mm/64: Make a full PGD-entry size hole in the memory map

[Thomas Gleixner]

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@xxxxxxxxxx>
> > 
> > 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)
> > 
> > 
>