linux-kernel - [Patch v3 0/7] Optimize clear dirty log

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Date:   Fri, 10 Feb 2023 17:46:19 -0800
From:   Vipin Sharma <vipinsh@...gle.com>
To:     seanjc@...gle.com, pbonzini@...hat.com, bgardon@...gle.com,
        dmatlack@...gle.com
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Vipin Sharma <vipinsh@...gle.com>
Subject: [Patch v3 0/7] Optimize clear dirty log

Hi,


This patch series has optimized control flow of clearing dirty log and
improved its performance by ~40% (2% more than v2).

It also got rid of many variants of the handle_changed_spte family of
functions and converged logic to one handle_changed_spte() function. It
also remove tdp_mmu_set_spte_no_[acc_track|dirty_log] and various
booleans for controlling them.

Thanks,
Vipin

v3:
- Tried to do better job at writing commit messages.
- Made kvm_tdp_mmu_clear_spte_bits() similar to the kvm_tdp_mmu_write_spte().
- clear_dirty_pt_masked() evaluates mask for the bit to be cleared outside the
  loop and use that for all of the SPTEs instead of calculating for each SPTE.
- Some naming changes based on the feedbacks.
- Split out the dead code clean from the optimization code.


v2: https://lore.kernel.org/lkml/20230203192822.106773-1-vipinsh@google.com/
- Clear dirty log and age gfn range does not go through
  handle_changed_spte, they handle their SPTE changes locally to improve
  their speed.
- Clear only specific bits atomically when updating SPTEs in clearing
  dirty log and aging gfn range functions.
- Removed tdp_mmu_set_spte_no_[acc_track|dirty_log] APIs.
- Converged all handle_changed_spte related functions to one place.

v1: https://lore.kernel.org/lkml/20230125213857.824959-1-vipinsh@google.com/


Vipin Sharma (7):
  KVM: x86/mmu: Add a helper function to check if an SPTE needs atomic
    write
  KVM: x86/mmu: Atomically clear SPTE dirty state in the clear-dirty-log
    flow
  KVM: x86/mmu: Remove "record_dirty_log" in __tdp_mmu_set_spte()
  KVM: x86/mmu: Optimize SPTE change for aging gfn range
  KVM: x86/mmu: Remove "record_acc_track" in __tdp_mmu_set_spte()
  KVM: x86/mmu: Remove handle_changed_spte_dirty_log()
  KVM: x86/mmu: Merge all handle_changed_pte* functions.

 arch/x86/kvm/mmu/tdp_iter.h |  48 ++++++---
 arch/x86/kvm/mmu/tdp_mmu.c  | 190 ++++++++++++------------------------
 2 files changed, 96 insertions(+), 142 deletions(-)

-- 
2.39.1.581.gbfd45094c4-goog