From patchwork Mon Apr 27 21:07:43 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marcelo Tosatti X-Patchwork-Id: 20258 Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n3RLA6b9029712 for ; Mon, 27 Apr 2009 21:10:06 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755025AbZD0VKB (ORCPT ); Mon, 27 Apr 2009 17:10:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753429AbZD0VKB (ORCPT ); Mon, 27 Apr 2009 17:10:01 -0400 Received: from mx2.redhat.com ([66.187.237.31]:36483 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753361AbZD0VJ5 (ORCPT ); Mon, 27 Apr 2009 17:09:57 -0400 Received: from int-mx2.corp.redhat.com (int-mx2.corp.redhat.com [172.16.27.26]) by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id n3RL9wqI002312; Mon, 27 Apr 2009 17:09:58 -0400 Received: from ns3.rdu.redhat.com (ns3.rdu.redhat.com [10.11.255.199]) by int-mx2.corp.redhat.com (8.13.1/8.13.1) with ESMTP id n3RL9uTR017891; Mon, 27 Apr 2009 17:09:57 -0400 Received: from amt.cnet (vpn-10-9.str.redhat.com [10.32.10.9]) by ns3.rdu.redhat.com (8.13.8/8.13.8) with ESMTP id n3RL9pJY027147; Mon, 27 Apr 2009 17:09:52 -0400 Received: from amt.cnet (amt.cnet [127.0.0.1]) by amt.cnet (Postfix) with ESMTP id 8B688274040; Mon, 27 Apr 2009 18:09:23 -0300 (BRT) Received: (from marcelo@localhost) by amt.cnet (8.14.3/8.14.3/Submit) id n3RL9JtU011661; Mon, 27 Apr 2009 18:09:19 -0300 Message-Id: <20090427210840.123459406@amt.cnet> User-Agent: quilt/0.47-1 Date: Mon, 27 Apr 2009 18:07:43 -0300 From: mtosatti@redhat.com To: kvm@vger.kernel.org Cc: sheng@linux.intel.com, Marcelo Tosatti Subject: [patch 3/4] KVM: use smp_send_reschedule in kvm_vcpu_kick References: <20090427210740.675732111@amt.cnet> Content-Disposition: inline; filename=smp-ipi X-Scanned-By: MIMEDefang 2.58 on 172.16.27.26 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org KVM uses a function call IPI to cause the exit of a guest running on a physical cpu. For virtual interrupt notification there is no need to wait on IPI receival, or to execute any function. This is exactly what the reschedule IPI does, without the overhead of function IPI. So use it instead of smp_call_function_single in kvm_vcpu_kick. Also change the "guest_mode" variable to a bit in vcpu->requests, and use that to collapse multiple IPI's that would be issued between the first one and zeroing of guest mode. This allows kvm_vcpu_kick to called with interrupts disabled. Signed-off-by: Marcelo Tosatti --- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Index: kvm/arch/ia64/kernel/irq_ia64.c =================================================================== --- kvm.orig/arch/ia64/kernel/irq_ia64.c +++ kvm/arch/ia64/kernel/irq_ia64.c @@ -610,6 +610,9 @@ static struct irqaction ipi_irqaction = .name = "IPI" }; +/* + * KVM uses this interrupt to force a cpu out of guest mode + */ static struct irqaction resched_irqaction = { .handler = dummy_handler, .flags = IRQF_DISABLED, Index: kvm/arch/ia64/kvm/kvm-ia64.c =================================================================== --- kvm.orig/arch/ia64/kvm/kvm-ia64.c +++ kvm/arch/ia64/kvm/kvm-ia64.c @@ -668,7 +668,7 @@ again: host_ctx = kvm_get_host_context(vcpu); guest_ctx = kvm_get_guest_context(vcpu); - vcpu->guest_mode = 1; + clear_bit(KVM_REQ_KICK, &vcpu->requests); r = kvm_vcpu_pre_transition(vcpu); if (r < 0) @@ -685,7 +685,7 @@ again: kvm_vcpu_post_transition(vcpu); vcpu->arch.launched = 1; - vcpu->guest_mode = 0; + set_bit(KVM_REQ_KICK, &vcpu->requests); local_irq_enable(); /* @@ -1884,24 +1884,18 @@ void kvm_arch_hardware_unsetup(void) { } -static void vcpu_kick_intr(void *info) -{ -#ifdef DEBUG - struct kvm_vcpu *vcpu = (struct kvm_vcpu *)info; - printk(KERN_DEBUG"vcpu_kick_intr %p \n", vcpu); -#endif -} - void kvm_vcpu_kick(struct kvm_vcpu *vcpu) { - int ipi_pcpu = vcpu->cpu; - int cpu = get_cpu(); + int me; + int cpu = vcpu->cpu; if (waitqueue_active(&vcpu->wq)) wake_up_interruptible(&vcpu->wq); - if (vcpu->guest_mode && cpu != ipi_pcpu) - smp_call_function_single(ipi_pcpu, vcpu_kick_intr, vcpu, 0); + me = get_cpu(); + if (cpu != me && (unsigned) cpu < nr_cpu_ids && cpu_online(cpu)) + if (!test_and_set_bit(KVM_REQ_KICK, &vcpu->requests)) + smp_send_reschedule(cpu); put_cpu(); } Index: kvm/arch/x86/kernel/smp.c =================================================================== --- kvm.orig/arch/x86/kernel/smp.c +++ kvm/arch/x86/kernel/smp.c @@ -172,6 +172,9 @@ void smp_reschedule_interrupt(struct pt_ { ack_APIC_irq(); inc_irq_stat(irq_resched_count); + /* + * KVM uses this interrupt to force a cpu out of guest mode + */ } void smp_call_function_interrupt(struct pt_regs *regs) Index: kvm/arch/x86/kvm/x86.c =================================================================== --- kvm.orig/arch/x86/kvm/x86.c +++ kvm/arch/x86/kvm/x86.c @@ -3197,6 +3197,9 @@ static int vcpu_enter_guest(struct kvm_v local_irq_disable(); + clear_bit(KVM_REQ_KICK, &vcpu->requests); + smp_mb__after_clear_bit(); + if (vcpu->requests || need_resched() || signal_pending(current)) { local_irq_enable(); preempt_enable(); @@ -3204,13 +3207,6 @@ static int vcpu_enter_guest(struct kvm_v goto out; } - vcpu->guest_mode = 1; - /* - * Make sure that guest_mode assignment won't happen after - * testing the pending IRQ vector bitmap. - */ - smp_wmb(); - if (vcpu->arch.exception.pending) __queue_exception(vcpu); else if (irqchip_in_kernel(vcpu->kvm)) @@ -3252,7 +3248,7 @@ static int vcpu_enter_guest(struct kvm_v set_debugreg(vcpu->arch.host_dr6, 6); set_debugreg(vcpu->arch.host_dr7, 7); - vcpu->guest_mode = 0; + set_bit(KVM_REQ_KICK, &vcpu->requests); local_irq_enable(); ++vcpu->stat.exits; @@ -4550,30 +4546,20 @@ int kvm_arch_vcpu_runnable(struct kvm_vc || vcpu->arch.nmi_pending; } -static void vcpu_kick_intr(void *info) -{ -#ifdef DEBUG - struct kvm_vcpu *vcpu = (struct kvm_vcpu *)info; - printk(KERN_DEBUG "vcpu_kick_intr %p \n", vcpu); -#endif -} - void kvm_vcpu_kick(struct kvm_vcpu *vcpu) { - int ipi_pcpu = vcpu->cpu; - int cpu; + int me; + int cpu = vcpu->cpu; if (waitqueue_active(&vcpu->wq)) { wake_up_interruptible(&vcpu->wq); ++vcpu->stat.halt_wakeup; } - /* - * We may be called synchronously with irqs disabled in guest mode, - * So need not to call smp_call_function_single() in that case. - */ - cpu = get_cpu(); - if (vcpu->guest_mode && vcpu->cpu != cpu) - smp_call_function_single(ipi_pcpu, vcpu_kick_intr, vcpu, 0); + + me = get_cpu(); + if (cpu != me && (unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) + if (!test_and_set_bit(KVM_REQ_KICK, &vcpu->requests)) + smp_send_reschedule(cpu); put_cpu(); } Index: kvm/include/linux/kvm_host.h =================================================================== --- kvm.orig/include/linux/kvm_host.h +++ kvm/include/linux/kvm_host.h @@ -38,6 +38,7 @@ #define KVM_REQ_UNHALT 6 #define KVM_REQ_MMU_SYNC 7 #define KVM_REQ_KVMCLOCK_UPDATE 8 +#define KVM_REQ_KICK 9 #define KVM_USERSPACE_IRQ_SOURCE_ID 0 @@ -72,7 +73,6 @@ struct kvm_vcpu { struct mutex mutex; int cpu; struct kvm_run *run; - int guest_mode; unsigned long requests; unsigned long guest_debug; int fpu_active;