Messages in this thread | | | Subject | Re: [PATCH] KVM: x86/mmu: Skip !MMU-present SPTEs when removing SP in exclusive mode | From | Paolo Bonzini <> | Date | Wed, 10 Mar 2021 10:08:05 +0100 |
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On 10/03/21 01:30, Sean Christopherson wrote: > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index 50ef757c5586..f0c99fa04ef2 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -323,7 +323,18 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, u64 *pt, > cpu_relax(); > } > } else { > + /* > + * If the SPTE is not MMU-present, there is no backing > + * page associated with the SPTE and so no side effects > + * that need to be recorded, and exclusive ownership of > + * mmu_lock ensures the SPTE can't be made present. > + * Note, zapping MMIO SPTEs is also unnecessary as they > + * are guarded by the memslots generation, not by being > + * unreachable. > + */ > old_child_spte = READ_ONCE(*sptep); > + if (!is_shadow_present_pte(old_child_spte)) > + continue; > > /* > * Marking the SPTE as a removed SPTE is not
Ben, do you plan to make this path take mmu_lock for read? If so, this wouldn't be too useful IIUC.
Paolo
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