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KVM: x86/mmu: Bypass __handle_changed_spte() when aging TDP MMU SPTEs

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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]
Link: https://lore.kernel.org/r/20230321220021.2119033-11-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Vipin Sharma 2023-03-21 15:00:18 -07:00 committed by Sean Christopherson
parent 6141df067d
commit 891f115960
1 changed files with 2 additions and 2 deletions
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4
arch/x86/kvm/mmu/tdp_mmu.c
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@ -1275,8 +1275,8 @@ static bool age_gfn_range(struct kvm *kvm, struct tdp_iter *iter,
iter->level); iter->level);
} }
__handle_changed_spte(kvm, iter->as_id, iter->gfn, iter->old_spte, trace_kvm_tdp_mmu_spte_changed(iter->as_id, iter->gfn, iter->level,
new_spte, iter->level, false); iter->old_spte, new_spte);
return true; return true;
} }