Messages in this thread Patch in this message | | | Subject | Re: AVIC related warning in enable_irq_window | From | Suravee Suthikulpanit <> | Date | Mon, 4 May 2020 17:37:44 +0700 |
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Paolo / Maxim,
On 5/4/20 4:25 PM, Paolo Bonzini wrote: > On 04/05/20 11:13, Maxim Levitsky wrote: >> On Mon, 2020-05-04 at 15:46 +0700, Suravee Suthikulpanit wrote: >>> Paolo / Maxim, >>> >>> On 5/2/20 11:42 PM, Paolo Bonzini wrote: >>>> On 02/05/20 15:58, Maxim Levitsky wrote: >>>>> The AVIC is disabled by svm_toggle_avic_for_irq_window, which calls >>>>> kvm_request_apicv_update, which broadcasts the KVM_REQ_APICV_UPDATE vcpu request, >>>>> however it doesn't broadcast it to CPU on which now we are running, which seems OK, >>>>> because the code that handles that broadcast runs on each VCPU entry, thus >>>>> when this CPU will enter guest mode it will notice and disable the AVIC. >>>>> >>>>> However later in svm_enable_vintr, there is test 'WARN_ON(kvm_vcpu_apicv_active(&svm->vcpu));' >>>>> which is still true on current CPU because of the above. >>>> >>>> Good point! We can just remove the WARN_ON I think. Can you send a patch? >>> >>> Instead, as an alternative to remove the WARN_ON(), would it be better to just explicitly >>> calling kvm_vcpu_update_apicv(vcpu) to update the apicv_active flag right after >>> kvm_request_apicv_update()? >>> >> This should work IMHO, other that the fact kvm_vcpu_update_apicv will be called again, >> when this vcpu is entered since the KVM_REQ_APICV_UPDATE will still be pending on it. >> It shoudn't be a problem, and we can even add a check to do nothing when it is called >> while avic is already in target enable state. > > I thought about that but I think it's a bit confusing. If we want to > keep the WARN_ON, Maxim can add an equivalent one to svm_vcpu_run, which > is even better because the invariant is clearer. > > WARN_ON((vmcb->control.int_ctl & (AVIC_ENABLE_MASK | V_IRQ_MASK)) > == (AVIC_ENABLE_MASK | V_IRQ_MASK)); > > Paolo >
Quick update. I tried your suggestion as following, and it's showing the warning still. I'll look further into this.
arch/x86/kvm/svm/svm.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 2f379ba..142c4b9 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1368,9 +1368,6 @@ static inline void svm_enable_vintr(struct vcpu_svm *svm) { struct vmcb_control_area *control;
- /* The following fields are ignored when AVIC is enabled */ - WARN_ON(kvm_vcpu_apicv_active(&svm->vcpu)); - /* * This is just a dummy VINTR to actually cause a vmexit to happen. * Actual injection of virtual interrupts happens through EVENTINJ. @@ -3322,6 +3319,11 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu) vcpu->arch.apic->lapic_timer.timer_advance_ns) kvm_wait_lapic_expire(vcpu);
+//SURAVEE + WARN_ON((svm->vmcb->control.int_ctl & + (AVIC_ENABLE_MASK | V_IRQ_MASK)) + == (AVIC_ENABLE_MASK | V_IRQ_MASK)); +
Suravee
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