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charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Hi Jing, On Tue, Jan 18, 2022 at 1:57 AM Jing Zhang wrote: > > To reduce MMU lock contention during dirty logging, all permission > relaxation operations would be performed under read lock. > > Signed-off-by: Jing Zhang > --- > arch/arm64/kvm/mmu.c | 17 +++++++++++++++-- > 1 file changed, 15 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index cafd5813c949..10df5d855d54 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -1080,6 +1080,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > gfn_t gfn; > kvm_pfn_t pfn; > bool logging_active = memslot_is_logging(memslot); > + bool logging_perm_fault = false; > unsigned long fault_level = kvm_vcpu_trap_get_fault_level(vcpu); > unsigned long vma_pagesize, fault_granule; > enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R; > @@ -1114,6 +1115,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > if (logging_active) { > force_pte = true; > vma_shift = PAGE_SHIFT; > + logging_perm_fault = (fault_status == FSC_PERM && write_fault); > } else { > vma_shift = get_vma_page_shift(vma, hva); > } > @@ -1212,7 +1214,15 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > if (exec_fault && device) > return -ENOEXEC; > > - write_lock(&kvm->mmu_lock); > + /* > + * To reduce MMU contentions and enhance concurrency during dirty > + * logging dirty logging, only acquire read lock for permission > + * relaxation. > + */ A couple of nits: "dirty logging" is repeated twice s/contentions/contention Other than that, Tested-by: Fuad Tabba Reviewed-by: Fuad Tabba Thanks, /fuad > + if (logging_perm_fault) > + read_lock(&kvm->mmu_lock); > + else > + write_lock(&kvm->mmu_lock); > pgt = vcpu->arch.hw_mmu->pgt; > if (mmu_notifier_retry(kvm, mmu_seq)) > goto out_unlock; > @@ -1271,7 +1281,10 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > } > > out_unlock: > - write_unlock(&kvm->mmu_lock); > + if (logging_perm_fault) > + read_unlock(&kvm->mmu_lock); > + else > + write_unlock(&kvm->mmu_lock); > kvm_set_pfn_accessed(pfn); > kvm_release_pfn_clean(pfn); > return ret != -EAGAIN ? ret : 0; > -- > 2.34.1.703.g22d0c6ccf7-goog > > _______________________________________________ > kvmarm mailing list > kvmarm@lists.cs.columbia.edu > https://lists.cs.columbia.edu/mailman/listinfo/kvmarm _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BA369C433EF for ; Tue, 25 Jan 2022 13:25:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1576591AbiAYNZa (ORCPT ); Tue, 25 Jan 2022 08:25:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50688 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1576565AbiAYNXN (ORCPT ); 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charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi Jing, On Tue, Jan 18, 2022 at 1:57 AM Jing Zhang wrote: > > To reduce MMU lock contention during dirty logging, all permission > relaxation operations would be performed under read lock. > > Signed-off-by: Jing Zhang > --- > arch/arm64/kvm/mmu.c | 17 +++++++++++++++-- > 1 file changed, 15 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index cafd5813c949..10df5d855d54 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -1080,6 +1080,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > gfn_t gfn; > kvm_pfn_t pfn; > bool logging_active = memslot_is_logging(memslot); > + bool logging_perm_fault = false; > unsigned long fault_level = kvm_vcpu_trap_get_fault_level(vcpu); > unsigned long vma_pagesize, fault_granule; > enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R; > @@ -1114,6 +1115,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > if (logging_active) { > force_pte = true; > vma_shift = PAGE_SHIFT; > + logging_perm_fault = (fault_status == FSC_PERM && write_fault); > } else { > vma_shift = get_vma_page_shift(vma, hva); > } > @@ -1212,7 +1214,15 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > if (exec_fault && device) > return -ENOEXEC; > > - write_lock(&kvm->mmu_lock); > + /* > + * To reduce MMU contentions and enhance concurrency during dirty > + * logging dirty logging, only acquire read lock for permission > + * relaxation. > + */ A couple of nits: "dirty logging" is repeated twice s/contentions/contention Other than that, Tested-by: Fuad Tabba Reviewed-by: Fuad Tabba Thanks, /fuad > + if (logging_perm_fault) > + read_lock(&kvm->mmu_lock); > + else > + write_lock(&kvm->mmu_lock); > pgt = vcpu->arch.hw_mmu->pgt; > if (mmu_notifier_retry(kvm, mmu_seq)) > goto out_unlock; > @@ -1271,7 +1281,10 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > } > > out_unlock: > - write_unlock(&kvm->mmu_lock); > + if (logging_perm_fault) > + read_unlock(&kvm->mmu_lock); > + else > + write_unlock(&kvm->mmu_lock); > kvm_set_pfn_accessed(pfn); > kvm_release_pfn_clean(pfn); > return ret != -EAGAIN ? ret : 0; > -- > 2.34.1.703.g22d0c6ccf7-goog > > _______________________________________________ > kvmarm mailing list > kvmarm@lists.cs.columbia.edu > https://lists.cs.columbia.edu/mailman/listinfo/kvmarm