Re: [PATCH 2/2] KVM: x86: Fix split-irqchip vs interrupt injection window request

On 15/04/21 02:59, Lai Jiangshan wrote:

The next call to inject_pending_event() will reach here AT FIRST with vcpu->arch.exception.injected==false and vcpu->arch.exception.pending==false

...

      ... if (!vcpu->arch.exception.pending) {
              if (vcpu->arch.nmi_injected) {
                      static_call(kvm_x86_set_nmi)(vcpu);
                      can_inject = false;
              } else if (vcpu->arch.interrupt.injected) {
                      static_call(kvm_x86_set_irq)(vcpu);
                      can_inject = false;

And comes here and vcpu->arch.interrupt.injected is true for there is an interrupt queued by KVM_INTERRUPT for pure user irqchip. It then does the injection of the interrupt without checking the EFLAGS.IF.

Ok, understood now. Yeah, that could be a problem for userspace irqchip so we should switch it to use pending_external_vector instead. Are you going to write the patch or should I?

Thanks!

Paolo

My question is that what stops the next call to inject_pending_event() to reach here when KVM_INTERRUPT is called with exepction pending.