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[v4,10/13] KVM: x86/mmu: Bypass __handle_changed_spte() when aging TDP MMU SPTEs

Message ID 20230321220021.2119033-11-seanjc@google.com (mailing list archive)
State New, archived
Headers show
Series KVM: x86/mmu: Optimize clear dirty log | expand

Commit Message

Sean Christopherson March 21, 2023, 10 p.m. UTC 
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(-)
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Patch

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;
 }