2017-08-24 17:13 GMT+08:00 Wanpeng Li <kernellwp@xxxxxxxxx>: > 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. > > Regards, > Wanpeng Li I observed sometimes both vcpu->arch.exception.pending and vcpu->arch.expception.injected are true before executing below codes: if (vcpu->arch.exception.injected) { kvm_x86_ops->queue_exception(vcpu); return 0; } 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