From: Andy Lutomirski <luto@kernel.org>
Date: Tue, 12 Dec 2017 07:56:44 -0800
Subject: x86/mm/64: Make a full PGD-entry size hole in the memory map
Git-commit: 9f449772a3106bcdd4eb8fdeb281147b0e99fb30
Patch-mainline: v4.15-rc6
References: bsc#1068032 CVE-2017-5754

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.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Borislav Petkov <bp@suse.de>
---
 Documentation/x86/x86_64/mm.txt         |    4 ++--
 arch/x86/include/asm/pgtable_64_types.h |    4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

--- a/arch/x86/include/asm/pgtable_64_types.h
+++ b/arch/x86/include/asm/pgtable_64_types.h
@@ -84,8 +84,8 @@ typedef struct { pteval_t pte; } pte_t;
 #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)
--- a/Documentation/x86/x86_64/mm.txt
+++ b/Documentation/x86/x86_64/mm.txt
@@ -30,8 +30,8 @@ Virtual memory map with 5 level page tab
 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 ...