[Patch v3 0/7] Optimize clear dirty log

Vipin Sharma
2023-02-11T01:46:38Z

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(-)

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2.39.1.581.gbfd45094c4-goog