Messages in this thread | | | Subject | Re: [PATCH 2/5] KVM: x86: do not scan IRR twice on APICv vmentry | From | Paolo Bonzini <> | Date | Thu, 3 Nov 2016 19:18:00 +0100 |
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On 03/11/2016 19:07, Radim Krčmář wrote: > 2016-11-03 17:00+0100, Paolo Bonzini: >> On 03/11/2016 16:03, Radim Krčmář wrote: >>> 2016-11-03 14:30+0100, Paolo Bonzini: >>>> On 26/10/2016 21:59, Radim Krčmář wrote: >>>>> 2016-10-14 20:21+0200, Paolo Bonzini: >>>>>> Calling apic_find_highest_irr results in IRR being scanned twice, >>>>>> once in vmx_sync_pir_from_irr and once in apic_search_irr. Change >>>>>> sync_pir_from_irr to do the RVI write and kvm_apic_update_irr to >>>>>> compute the new RVI on the fly. >>>>>> >>>>>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> >>>>>> --- >>>>> >>>>> Reviewed-by: Radim Krčmář <rkrcmar@redhat.com> >>>> >>>> Nope, this breaks nested VMX exit on external interrupt. For now I'm >>>> testing only patch 1 and will push that one only to kvm/next. > > Which hypervisor is being nested?
vmx.flat. :)
> I think a bug is likely for hypervisors that don't enable > PIN_BASED_EXT_INTR_MASK. The bug would trigger when > kvm_cpu_has_interrupt() in vmx_check_nested_events() in > kvm_arch_vcpu_runnable() queues the interrupt ... > but I didn't see how this would have caused a problem. :)
Ironically, _not_ enabling PIN_BASED_EXT_INTR_MASK and not using HALT activity state is the only case that passes of the four that vmx.flat tests.
Paolo
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