| Message ID | 20220118015703.3630552-3-jingzhangos@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ARM64: Guest performance improvement during dirty | expand |
Hi Jing, On Tue, Jan 18, 2022 at 1:57 AM Jing Zhang <jingzhangos@google.com> wrote: > > To reduce MMU lock contention during dirty logging, all permission > relaxation operations would be performed under read lock. > > Signed-off-by: Jing Zhang <jingzhangos@google.com> > --- > 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 <tabba@google.com> Reviewed-by: Fuad Tabba <tabba@google.com> 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
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. + */ + 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;
To reduce MMU lock contention during dirty logging, all permission relaxation operations would be performed under read lock. Signed-off-by: Jing Zhang <jingzhangos@google.com> --- arch/arm64/kvm/mmu.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-)