Patch "x86/mm: Refactor flush_tlb_mm_range() to merge local and remote cases" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

x86/mm: Refactor flush_tlb_mm_range() to merge local and remote cases

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-mm-refactor-flush_tlb_mm_range-to-merge-local-and-remote-cases.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Andy Lutomirski <[email protected]>
Date: Sun, 28 May 2017 10:00:12 -0700
Subject: x86/mm: Refactor flush_tlb_mm_range() to merge local and remote cases

From: Andy Lutomirski <[email protected]>

commit 454bbad9793f59f5656ce5971ee473a8be736ef5 upstream.

The local flush path is very similar to the remote flush path. Merge them.

This is intended to make no difference to behavior whatsoever. It removes some code and will make future changes to the flushing mechanics simpler.

This patch does remove one small optimization: flush_tlb_mm_range() now has an unconditional smp_mb() instead of using MOV to CR3 or INVLPG as a full barrier when applicable. I think this is okay for a few reasons. First, smp_mb() is quite cheap compared to the cost of a TLB flush. Second, this rearrangement makes a bigger optimization available: with some work on the SMP function call code, we could do the local and remote flushes in parallel. Third, I'm planning a rework of the TLB flush algorithm that will require an atomic operation at the beginning of each flush, and that operation will replace the smp_mb().

---
 arch/x86/include/asm/tlbflush.h |    1 
 arch/x86/mm/tlb.c               |  111 +++++++++++++++++-----------------------
 2 files changed, 48 insertions(+), 64 deletions(-)

@@ -216,7 +216,6 @@ static inline void __flush_tlb_one(unsig
  * ..but the i386 has somewhat limited tlb flushing capabilities,
  * and page-granular flushes are available only on i486 and up.
  */
-
 struct flush_tlb_info {
 	struct mm_struct *mm;
 	unsigned long start;

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/x86-mm-refactor-flush_tlb_mm_range-to-merge-local-and-remote-cases.patch queue-4.9/x86-mm-pass-flush_tlb_info-to-flush_tlb_others-etc.patch queue-4.9/x86-mm-rework-lazy-tlb-to-track-the-actual-loaded-mm.patch queue-4.9/x86-mm-kvm-teach-kvm-s-vmx-code-that-cr3-isn-t-a-constant.patch queue-4.9/x86-mm-use-new-merged-flush-logic-in-arch_tlbbatch_flush.patch queue-4.9/x86-kvm-vmx-simplify-segment_base.patch queue-4.9/x86-entry-unwind-create-stack-frames-for-saved-interrupt-registers.patch queue-4.9/x86-mm-reduce-indentation-in-flush_tlb_func.patch queue-4.9/x86-mm-remove-the-up-asm-tlbflush.h-code-always-use-the-formerly-smp-code.patch queue-4.9/x86-mm-reimplement-flush_tlb_page-using-flush_tlb_mm_range.patch queue-4.9/mm-x86-mm-make-the-batched-unmap-tlb-flush-api-more-generic.patch queue-4.9/x86-kvm-vmx-defer-tr-reload-after-vm-exit.patch queue-4.9/x86-mm-change-the-leave_mm-condition-for-local-tlb-flushes.patch queue-4.9/x86-mm-be-more-consistent-wrt-page_shift-vs-page_size-in-tlb-flush-code.patch