Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755407AbcLNK7T (ORCPT ); Wed, 14 Dec 2016 05:59:19 -0500 Received: from mailhub.sw.ru ([195.214.232.25]:1674 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755284AbcLNK7R (ORCPT ); Wed, 14 Dec 2016 05:59:17 -0500 From: Denis Plotnikov To: rkagan@virtuozzo.com, den@virtuozzo.com, pbonzini@redhat.com, rkrcmar@redhat.com Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] KVM: x86: avoid redundant REQ_EVENT Date: Wed, 14 Dec 2016 13:59:08 +0300 Message-Id: <20161214105908.322638-1-dplotnikov@virtuozzo.com> X-Mailer: git-send-email 2.10.1.352.g0cf3611 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8826 Lines: 244 When processing KVM_REQ_EVENT, apic_update_ppr is called which may set KVM_REQ_EVENT again if the recalculated value of PPR becomes smaller than the previous one. This results in cancelling the guest entry and reiterating in vcpu_enter_guest. However this is unnecessary because at this point KVM_REQ_EVENT is already being processed and there are no other changes in the lapic that may require full-fledged state recalculation. This situation is often hit on systems with TPR shadow, where the TPR can be updated by the guest without a vmexit, so that the first apic_update_ppr to notice it is exactly the one called while processing KVM_REQ_EVENT. To avoid it, introduce a parameter in apic_update_ppr allowing to suppress setting of KVM_REQ_EVENT, and use it on the paths called from KVM_REQ_EVENT processing. Also add the parameter to kvm_cpu_get_interrupt to be passed through to apic_update_ppr to make sure the supression of KVM_REQ_EVENT is done in the KVM_REQ_EVENT processing path only. This microoptimization gives 10% performance increase on a synthetic test doing a lot of IPC in Windows using window messages. Reviewed-by: Roman Kagan Signed-off-by: Denis Plotnikov --- arch/x86/include/asm/kvm_host.h | 2 +- arch/x86/kvm/irq.c | 8 ++++---- arch/x86/kvm/lapic.c | 26 +++++++++++++------------- arch/x86/kvm/lapic.h | 4 ++-- arch/x86/kvm/vmx.c | 2 +- arch/x86/kvm/x86.c | 2 +- 6 files changed, 22 insertions(+), 22 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index bdde807..628c1d1 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1331,7 +1331,7 @@ void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte); int kvm_cpu_has_injectable_intr(struct kvm_vcpu *v); int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu); int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu); -int kvm_cpu_get_interrupt(struct kvm_vcpu *v); +int kvm_cpu_get_interrupt(struct kvm_vcpu *v, bool make_req); void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event); void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu); void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm, diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c index 60d91c9..b6125be 100644 --- a/arch/x86/kvm/irq.c +++ b/arch/x86/kvm/irq.c @@ -82,7 +82,7 @@ int kvm_cpu_has_injectable_intr(struct kvm_vcpu *v) if (kvm_vcpu_apicv_active(v)) return 0; - return kvm_apic_has_interrupt(v) != -1; /* LAPIC */ + return kvm_apic_has_interrupt(v, false) != -1; /* LAPIC */ } /* @@ -97,7 +97,7 @@ int kvm_cpu_has_interrupt(struct kvm_vcpu *v) if (kvm_cpu_has_extint(v)) return 1; - return kvm_apic_has_interrupt(v) != -1; /* LAPIC */ + return kvm_apic_has_interrupt(v, true) != -1; /* LAPIC */ } EXPORT_SYMBOL_GPL(kvm_cpu_has_interrupt); @@ -122,7 +122,7 @@ static int kvm_cpu_get_extint(struct kvm_vcpu *v) /* * Read pending interrupt vector and intack. */ -int kvm_cpu_get_interrupt(struct kvm_vcpu *v) +int kvm_cpu_get_interrupt(struct kvm_vcpu *v, bool make_req) { int vector; @@ -134,7 +134,7 @@ int kvm_cpu_get_interrupt(struct kvm_vcpu *v) if (vector != -1) return vector; /* PIC */ - return kvm_get_apic_interrupt(v); /* APIC */ + return kvm_get_apic_interrupt(v, make_req); /* APIC */ } EXPORT_SYMBOL_GPL(kvm_cpu_get_interrupt); diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 6f69340..7ec777d 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -544,7 +544,7 @@ static void pv_eoi_clr_pending(struct kvm_vcpu *vcpu) __clear_bit(KVM_APIC_PV_EOI_PENDING, &vcpu->arch.apic_attention); } -static void apic_update_ppr(struct kvm_lapic *apic) +static void apic_update_ppr(struct kvm_lapic *apic, bool make_req) { u32 tpr, isrv, ppr, old_ppr; int isr; @@ -564,7 +564,7 @@ static void apic_update_ppr(struct kvm_lapic *apic) if (old_ppr != ppr) { kvm_lapic_set_reg(apic, APIC_PROCPRI, ppr); - if (ppr < old_ppr) + if (make_req && ppr < old_ppr) kvm_make_request(KVM_REQ_EVENT, apic->vcpu); } } @@ -572,7 +572,7 @@ static void apic_update_ppr(struct kvm_lapic *apic) static void apic_set_tpr(struct kvm_lapic *apic, u32 tpr) { kvm_lapic_set_reg(apic, APIC_TASKPRI, tpr); - apic_update_ppr(apic); + apic_update_ppr(apic, true); } static bool kvm_apic_broadcast(struct kvm_lapic *apic, u32 mda) @@ -1032,7 +1032,7 @@ static int apic_set_eoi(struct kvm_lapic *apic) return vector; apic_clear_isr(vector, apic); - apic_update_ppr(apic); + apic_update_ppr(apic, true); if (test_bit(vector, vcpu_to_synic(apic->vcpu)->vec_bitmap)) kvm_hv_synic_send_eoi(apic->vcpu, vector); @@ -1147,7 +1147,7 @@ static u32 __apic_read(struct kvm_lapic *apic, unsigned int offset) val = apic_get_tmcct(apic); break; case APIC_PROCPRI: - apic_update_ppr(apic); + apic_update_ppr(apic, true); val = kvm_lapic_get_reg(apic, offset); break; case APIC_TASKPRI: @@ -1841,7 +1841,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event) kvm_lapic_set_base(vcpu, vcpu->arch.apic_base | MSR_IA32_APICBASE_BSP); vcpu->arch.pv_eoi.msr_val = 0; - apic_update_ppr(apic); + apic_update_ppr(apic, true); vcpu->arch.apic_arb_prio = 0; vcpu->arch.apic_attention = 0; @@ -1956,7 +1956,7 @@ int kvm_create_lapic(struct kvm_vcpu *vcpu) return -ENOMEM; } -int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu) +int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu, bool make_req) { struct kvm_lapic *apic = vcpu->arch.apic; int highest_irr; @@ -1964,7 +1964,7 @@ int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu) if (!apic_enabled(apic)) return -1; - apic_update_ppr(apic); + apic_update_ppr(apic, make_req); highest_irr = apic_find_highest_irr(apic); if ((highest_irr == -1) || ((highest_irr & 0xF0) <= kvm_lapic_get_reg(apic, APIC_PROCPRI))) @@ -1997,9 +1997,9 @@ void kvm_inject_apic_timer_irqs(struct kvm_vcpu *vcpu) } } -int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu) +int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu, bool make_req) { - int vector = kvm_apic_has_interrupt(vcpu); + int vector = kvm_apic_has_interrupt(vcpu, make_req); struct kvm_lapic *apic = vcpu->arch.apic; if (vector == -1) @@ -2013,12 +2013,12 @@ int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu) */ apic_set_isr(vector, apic); - apic_update_ppr(apic); + apic_update_ppr(apic, true); apic_clear_irr(vector, apic); if (test_bit(vector, vcpu_to_synic(vcpu)->auto_eoi_bitmap)) { apic_clear_isr(vector, apic); - apic_update_ppr(apic); + apic_update_ppr(apic, true); } return vector; @@ -2068,7 +2068,7 @@ int kvm_apic_set_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s) recalculate_apic_map(vcpu->kvm); kvm_apic_set_version(vcpu); - apic_update_ppr(apic); + apic_update_ppr(apic, true); hrtimer_cancel(&apic->lapic_timer.timer); apic_update_lvtt(apic); apic_manage_nmi_watchdog(apic, kvm_lapic_get_reg(apic, APIC_LVT0)); diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h index f60d01c..62c92c5 100644 --- a/arch/x86/kvm/lapic.h +++ b/arch/x86/kvm/lapic.h @@ -53,9 +53,9 @@ struct dest_map; int kvm_create_lapic(struct kvm_vcpu *vcpu); void kvm_free_lapic(struct kvm_vcpu *vcpu); -int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu); +int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu, bool make_req); int kvm_apic_accept_pic_intr(struct kvm_vcpu *vcpu); -int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu); +int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu, bool make_req); void kvm_apic_accept_events(struct kvm_vcpu *vcpu); void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event); u64 kvm_lapic_get_cr8(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 5382b82..d411079 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -10771,7 +10771,7 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason, if ((exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT) && nested_exit_intr_ack_set(vcpu)) { - int irq = kvm_cpu_get_interrupt(vcpu); + int irq = kvm_cpu_get_interrupt(vcpu, true); WARN_ON(irq < 0); vmcs12->vm_exit_intr_info = irq | INTR_INFO_VALID_MASK | INTR_TYPE_EXT_INTR; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 04c5d96..a7e51d3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6190,7 +6190,7 @@ static int inject_pending_event(struct kvm_vcpu *vcpu, bool req_int_win) return r; } if (kvm_x86_ops->interrupt_allowed(vcpu)) { - kvm_queue_interrupt(vcpu, kvm_cpu_get_interrupt(vcpu), + kvm_queue_interrupt(vcpu, kvm_cpu_get_interrupt(vcpu, false), false); kvm_x86_ops->set_irq(vcpu); } -- 2.10.1.352.g0cf3611