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KVM: x86/mmu: Check for a REMOVED leaf SPTE before making the SPTE
Explicitly check for a REMOVED leaf SPTE prior to attempting to map the final SPTE when handling a TDP MMU fault. Functionally, this is a nop as tdp_mmu_set_spte_atomic() will eventually detect the frozen SPTE. Pre-checking for a REMOVED SPTE is a minor optmization, but the real goal is to allow tdp_mmu_set_spte_atomic() to have an invariant that the "old" SPTE is never a REMOVED SPTE. Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Ben Gardon <bgardon@google.com> Message-Id: <20220226001546.360188-24-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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1 changed files with 5 additions and 1 deletions
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@ -1193,7 +1193,11 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
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}
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}
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if (iter.level != fault->goal_level) {
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/*
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* Force the guest to retry the access if the upper level SPTEs aren't
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* in place, or if the target leaf SPTE is frozen by another CPU.
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*/
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if (iter.level != fault->goal_level || is_removed_spte(iter.old_spte)) {
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rcu_read_unlock();
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return RET_PF_RETRY;
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}
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