On 24/08/2017 11:13, Wanpeng Li wrote:
> 2017-08-24 16:57 GMT+08:00 Paolo Bonzini <pbonzini@xxxxxxxxxx>:
>> On 24/08/2017 08:52, Wanpeng Li wrote:
>>>> @@ -6862,6 +6876,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
>>>> kvm_x86_ops->enable_nmi_window(vcpu);
>>>> if (kvm_cpu_has_injectable_intr(vcpu) || req_int_win)
>>>> kvm_x86_ops->enable_irq_window(vcpu);
>>>> + WARN_ON(vcpu->arch.exception.pending);
>>>
>>> This WARN_ON() is suggested during the review of last version,
>>> however, there are many cases in inject_pending_event() can result in
>>> return directly w/ vcpu->arch.exception.pending is true. Actually I
>>> have already catched the warning several times during the testing. I
>>> think we should remove it when committing.
>>
>> No, it's a good thing that it's failing, because it's finding a bug.
>> There's no such thing as an "exception window", so at the very least it
>
> Good point, the code looks good, I will fold it in next version.
> However, I still can observe the warning.
In patch 4, vmx_check_nested_events must clear vcpu->ex.pending.
Paolo
> Regards,
> Wanpeng Li
>
>> should set req_immediate_exit to true.
>>
>> Does this help?
>>
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index b698b2f135a2..76d5a192be6c 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -6365,14 +6365,20 @@ static int inject_pending_event(struct kvm_vcpu *vcpu, bool req_int_win)
>> return 0;
>> }
>>
>> - if (vcpu->arch.nmi_injected) {
>> - kvm_x86_ops->set_nmi(vcpu);
>> - return 0;
>> - }
>> + /*
>> + * Exceptions must be injected immediately, or the exception
>> + * frame will have the address of the NMI or interrupt handler.
>> + */
>> + if (!vcpu->arch.exception.pending) {
>> + if (vcpu->arch.nmi_injected) {
>> + kvm_x86_ops->set_nmi(vcpu);
>> + return 0;
>> + }
>>
>> - if (vcpu->arch.interrupt.pending) {
>> - kvm_x86_ops->set_irq(vcpu);
>> - return 0;
>> + if (vcpu->arch.interrupt.pending) {
>> + kvm_x86_ops->set_irq(vcpu);
>> + return 0;
>> + }
>> }
>>
>> if (is_guest_mode(vcpu) && kvm_x86_ops->check_nested_events) {
>>
>> Paolo
