Messages in this thread Patch in this message | | | From | Paolo Bonzini <> | Subject | Re: [PATCH v2 25/28] KVM: x86/mmu: Allow zapping collapsible SPTEs to use MMU read lock | Date | Wed, 3 Feb 2021 12:34:24 +0100 |
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On 02/02/21 19:57, Ben Gardon wrote: > @@ -1485,7 +1489,9 @@ void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm, > struct kvm_mmu_page *root; > int root_as_id; > > - for_each_tdp_mmu_root_yield_safe(kvm, root, false) { > + read_lock(&kvm->mmu_lock); > + > + for_each_tdp_mmu_root_yield_safe(kvm, root, true) { > root_as_id = kvm_mmu_page_as_id(root); > if (root_as_id != slot->as_id) > continue; > @@ -1493,6 +1499,8 @@ void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm, > zap_collapsible_spte_range(kvm, root, slot->base_gfn, > slot->base_gfn + slot->npages); > } > + > + read_unlock(&kvm->mmu_lock); > }
I'd prefer the functions to be consistent about who takes the lock, either mmu.c or tdp_mmu.c. Since everywhere else you're doing it in mmu.c, that would be:
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 0554d9c5c5d4..386ee4b703d9 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -5567,10 +5567,13 @@ void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm, write_lock(&kvm->mmu_lock); slot_handle_leaf(kvm, (struct kvm_memory_slot *)memslot, kvm_mmu_zap_collapsible_spte, true); + write_unlock(&kvm->mmu_lock);
- if (kvm->arch.tdp_mmu_enabled) + if (kvm->arch.tdp_mmu_enabled) { + read_lock(&kvm->mmu_lock); kvm_tdp_mmu_zap_collapsible_sptes(kvm, memslot); - write_unlock(&kvm->mmu_lock); + read_unlock(&kvm->mmu_lock); + } }
void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm, and just lockdep_assert_held_read here.
> - tdp_mmu_set_spte(kvm, &iter, 0); > - > - spte_set = true;
Is it correct to remove this assignment?
Paolo
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