[PATCH v2 0/5] mm/mprotect: avoid unnecessary TLB flushes

[Nadav Amit]

From: Nadav Amit <namit@xxxxxxxxxx>

This patch-set is intended to remove unnecessary TLB flushes. It is
based on feedback from v1 and several bugs I found in v1 myself.

Basically, there are 3 optimizations in this patch-set:
1. Avoiding TLB flushes on change_huge_pmd() that are only needed to
   prevent the A/D bits from changing.
2. Use TLB batching infrastructure to batch flushes across VMAs and
   do better/fewer flushes.
3. Avoid TLB flushes on permission demotion.

Andrea asked for the aforementioned (2) to come after (3), but this
is not simple (specifically since change_prot_numa() needs the number
of pages affected).

There are many changes from v1 to v2 so consider the change log as
partial.

v1->v2:
* Wrong detection of permission demotion [Andrea]
* Better comments [Andrea]
* Handle THP [Andrea]
* Batching across VMAs [Peter Xu]
* Avoid open-coding PTE analysis
* Fix wrong use of the mmu_gather()

Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxxxx>
Cc: x86@xxxxxxxxxx

Nadav Amit (5):
  x86: Detection of Knights Landing A/D leak
  mm: avoid unnecessary flush on change_huge_pmd()
  x86/mm: check exec permissions on fault
  mm/mprotect: use mmu_gather
  mm/mprotect: do not flush on permission promotion

 arch/x86/include/asm/cpufeatures.h   |  1 +
 arch/x86/include/asm/pgtable.h       |  8 +++
 arch/x86/include/asm/pgtable_types.h |  2 +
 arch/x86/include/asm/tlbflush.h      | 80 +++++++++++++++++++++++
 arch/x86/kernel/cpu/intel.c          |  5 ++
 arch/x86/mm/fault.c                  | 11 +++-
 fs/exec.c                            |  6 +-
 include/asm-generic/tlb.h            | 14 +++++
 include/linux/huge_mm.h              |  5 +-
 include/linux/mm.h                   |  5 +-
 include/linux/pgtable.h              |  5 ++
 mm/huge_memory.c                     | 22 ++++---
 mm/mprotect.c                        | 94 +++++++++++++++-------------
 mm/pgtable-generic.c                 |  8 +++
 mm/userfaultfd.c                     |  6 +-
 15 files changed, 215 insertions(+), 57 deletions(-)

-- 
2.25.1