The vcpu won't be wakened for a long time

["Longpeng (Mike, Cloud Infrastructure Service Product Dept.)" <longpeng2@xxxxxxxxxx>]

Hi guys,

We find a problem in kvm_vcpu_block().

The testcase is:
 - VM configured with 1 vcpu and 1 VF (using vfio-pci passthrough)
 - the vfio interrupt and the vcpu are bound to the same pcpu
 - using remapped mode IRTE, NOT posted mode

The bug was triggered when the vcpu executed HLT instruction:

kvm_vcpu_block:
    prepare_to_rcuwait(&vcpu->wait);
    for (;;) {
        set_current_state(TASK_INTERRUPTIBLE);

        if (kvm_vcpu_check_block(vcpu) < 0)
            break;
					<------------ (*)
        waited = true;
        schedule();
    }
    finish_rcuwait(&vcpu->wait);

The vcpu will go to sleep even if an interrupt from the VF is fired at (*) and
the PIR and ON bit will be set ( in vmx_deliver_posted_interrupt ), so the vcpu
won't be wakened by subsequent interrupts.

Any suggestions ? Thanks.