On 06/12/2017 19:52, Radim Krčmář wrote:
>> smp_mb__after_atomic();
>> max_irr = kvm_apic_update_irr(vcpu, vmx->pi_desc.pir);
> I think the optimization (partly livelock protection) is not worth the
> overhead of two IRR scans for non-nested guests. Please make
> kvm_apic_update_irr() return both prev_max_irr and max_irr in one pass.
You could also return max_irr in an int*, and give the function a "bool"
return type for max_irr > prev_max_irr. That is more efficient because
you can do the check in the "if (pir_val)" conditional of
__kvm_apic_update_irr.
Paolo
>> +
>> + /*
>> + * If we are running L2 and L1 has a new pending interrupt
>> + * which can be injected, we should re-evaluate
>> + * what should be done with this new L1 interrupt.
>> + */
>> + if (is_guest_mode(vcpu) && (max_irr > prev_max_irr))
>> + kvm_make_request(KVM_REQ_EVENT, vcpu);
> We don't need anything from KVM_REQ_EVENT and only use it to abort the
> VM entry, kvm_vcpu_exiting_guest_mode() is better for that.
>
>> } else {
>> - max_irr = kvm_lapic_find_highest_irr(vcpu);
>> + max_irr = prev_max_irr;
>> }
>> +
>> vmx_hwapic_irr_update(vcpu, max_irr);
> We also should just inject the interrupt if L2 is run without
> nested_exit_on_intr(), maybe reusing the check in vmx_hwapic_irr_update?
