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    Subject[PATCH v4 10/13] KVM: x86/mmu: Bypass __handle_changed_spte() when aging TDP MMU SPTEs
    From
    From: Vipin Sharma <vipinsh@google.com>

    Drop everything except the "tdp_mmu_spte_changed" tracepoint part of
    __handle_changed_spte() when aging SPTEs in the TDP MMU, as clearing the
    accessed status doesn't affect the SPTE's shadow-present status, whether
    or not the SPTE is a leaf, or change the PFN. I.e. none of the functional
    updates handled by __handle_changed_spte() are relevant.

    Losing __handle_changed_spte()'s sanity checks does mean that a bug could
    theoretical go unnoticed, but that scenario is extremely unlikely, e.g.
    would effectively require a misconfigured MMU or a locking bug elsewhere.

    Link: https://lore.kernel.org/all/Y9HcHRBShQgjxsQb@google.com
    Signed-off-by: Vipin Sharma <vipinsh@google.com>
    Reviewed-by: David Matlack <dmatlack@google.com>
    [sean: massage changelog]
    Signed-off-by: Sean Christopherson <seanjc@google.com>
    ---
    arch/x86/kvm/mmu/tdp_mmu.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
    index 29bb97ff266e..cdfb67ef5800 100644
    --- a/arch/x86/kvm/mmu/tdp_mmu.c
    +++ b/arch/x86/kvm/mmu/tdp_mmu.c
    @@ -1275,8 +1275,8 @@ static bool age_gfn_range(struct kvm *kvm, struct tdp_iter *iter,
    iter->level);
    }

    - __handle_changed_spte(kvm, iter->as_id, iter->gfn, iter->old_spte,
    - new_spte, iter->level, false);
    + trace_kvm_tdp_mmu_spte_changed(iter->as_id, iter->gfn, iter->level,
    + iter->old_spte, new_spte);
    return true;
    }

    --
    2.40.0.rc2.332.ga46443480c-goog
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