From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 2/3] KVM: nVMX: Fix fail to get nested ack intr's vector during nested vmexit Date: Thu, 17 Jul 2014 10:49:59 +0200 Message-ID: <53C78E37.5090807@redhat.com> References: <1405573011-41330-1-git-send-email-wanpeng.li@linux.intel.com> <1405573011-41330-2-git-send-email-wanpeng.li@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , Gleb Natapov , Bandan Das , Zhang Yang , Hu Robert , kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: Wanpeng Li , Jan Kiszka Return-path: Received: from mail-wi0-f175.google.com ([209.85.212.175]:63923 "EHLO mail-wi0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755510AbaGQJqe (ORCPT ); Thu, 17 Jul 2014 05:46:34 -0400 In-Reply-To: <1405573011-41330-2-git-send-email-wanpeng.li@linux.intel.com> Sender: kvm-owner@vger.kernel.org List-ID: Il 17/07/2014 06:56, Wanpeng Li ha scritto: > && nested_exit_intr_ack_set(vcpu)) { > int irq = kvm_cpu_get_interrupt(vcpu); > + > + if (irq < 0 && kvm_apic_vid_enabled(vcpu->kvm)) > + irq = kvm_get_apic_interrupt(vcpu); There's something weird in this patch. If you "inline" kvm_cpu_get_interrupt, what you get is this: int irq; /* Beginning of kvm_cpu_get_interrupt... */ if (!irqchip_in_kernel(v->kvm)) irq = v->arch.interrupt.nr; else { irq = kvm_cpu_get_extint(v); /* PIC */ if (!kvm_apic_vid_enabled(v->kvm) && irq == -1) irq = kvm_get_apic_interrupt(v); /* APIC */ } /* kvm_cpu_get_interrupt done. */ if (irq < 0 && kvm_apic_vid_enabled(vcpu->kvm)) irq = kvm_get_apic_interrupt(vcpu); There are just two callers of kvm_cpu_get_interrupt, and the other is protected by kvm_cpu_has_injectable_intr so it won't be executed if virtual interrupt delivery is enabled. So you patch is effectively the same as this: diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c index bd0da43..a1ec6a5 100644 --- a/arch/x86/kvm/irq.c +++ b/arch/x86/kvm/irq.c @@ -108,7 +108,7 @@ int kvm_cpu_get_interrupt(struct kvm_vcpu *v) vector = kvm_cpu_get_extint(v); - if (kvm_apic_vid_enabled(v->kvm) || vector != -1) + if (vector != -1) return vector; /* PIC */ return kvm_get_apic_interrupt(v); /* APIC */ But in kvm_get_apic_interrupt I have just added this comment: /* Note that we never get here with APIC virtualization * enabled. */ because kvm_get_apic_interrupt calls apic_set_isr, and apic_set_isr must never be called with APIC virtualization enabled either. With APIC virtualization enabled, isr_count is always 1, and highest_isr_cache is always -1, and apic_set_isr breaks both of these invariants. Paolo