From mboxrd@z Thu Jan 1 00:00:00 1970 From: Radim =?utf-8?B?S3LEjW3DocWZ?= Subject: Re: [PATCH 2/5] KVM: x86: do not scan IRR twice on APICv vmentry Date: Thu, 3 Nov 2016 19:29:31 +0100 Message-ID: <20161103182930.GG7771@potion> References: <1476469291-5039-1-git-send-email-pbonzini@redhat.com> <1476469291-5039-3-git-send-email-pbonzini@redhat.com> <20161026195900.GC4212@potion> <00273a1a-ef5d-f814-3e02-24b4e855d229@redhat.com> <20161103150356.GE7771@potion> <20161103180753.GF7771@potion> <18e681d1-640f-8c56-dc05-acc7ca34cd45@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, yang.zhang.wz@gmail.com, feng.wu@intel.com, mst@redhat.com To: Paolo Bonzini Return-path: Received: from mx1.redhat.com ([209.132.183.28]:41076 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760047AbcKCS3f (ORCPT ); Thu, 3 Nov 2016 14:29:35 -0400 Content-Disposition: inline In-Reply-To: <18e681d1-640f-8c56-dc05-acc7ca34cd45@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: 2016-11-03 19:18+0100, Paolo Bonzini: > 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 >>>>>>> --- >>>>>> >>>>>> Reviewed-by: Radim Krčmář >>>>> >>>>> 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. Heh, the behavior is nice PASS: direct interrupt + hlt FAIL: intercepted interrupt + hlt FAIL: direct interrupt + activity state hlt FAIL: intercepted interrupt + activity state hlt