linux-kernel - [PATCH 0/5 v2] KVM: x86: MMU: Eliminate extra memory slot searches in page fault handlers

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Message-Id: <20151016170315.779ef31701287a3826b44892@lab.ntt.co.jp>
Date:	Fri, 16 Oct 2015 17:03:15 +0900
From:	Takuya Yoshikawa <yoshikawa_takuya_b1@....ntt.co.jp>
To:	pbonzini@...hat.com
Cc:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 0/5 v2] KVM: x86: MMU: Eliminate extra memory slot searches
 in page fault handlers

v2: Based on Paolo's suggestion, kept the common code as much as possible by
    introducing memslot_valid_for_gpte().

    Note: instead of joining all checks by boolean operators, splitted the
    no_dirty_log case off to be a separate if-check because it is checking
    clearly different thing than the rest.  See patch 4 for details.

In page fault handlers, both mapping_level_dirty_bitmap() and mapping_level()
do a memory slot search, binary search, through kvm_vcpu_gfn_to_memslot(), which
may not be negligible especially for virtual machines with many memory slots.

With a bit of cleanup effort, the patch set reduces this overhead.

	Takuya

Takuya Yoshikawa (5):
  KVM: x86: MMU: Make force_pt_level bool
  KVM: x86: MMU: Simplify force_pt_level calculation code in FNAME(page_fault)()
  KVM: x86: MMU: Merge mapping_level_dirty_bitmap() into mapping_level()
  KVM: x86: MMU: Remove mapping_level_dirty_bitmap()
  KVM: x86: MMU: Eliminate an extra memory slot search in mapping_level()

 arch/x86/kvm/mmu.c         | 70 +++++++++++++++++++++++++++-------------------
 arch/x86/kvm/paging_tmpl.h | 19 ++++++-------
 2 files changed, 50 insertions(+), 39 deletions(-)

-- 
2.1.0

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