Messages in this thread Patch in this message | | | Date | Thu, 17 Jul 2014 10:49:59 +0200 | From | Paolo Bonzini <> | Subject | Re: [PATCH 2/3] KVM: nVMX: Fix fail to get nested ack intr's vector during nested vmexit |
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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
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