From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [Qemu-devel] KVM: Windows 64-bit troubles with user space irqchip Date: Wed, 02 Feb 2011 17:09:01 +0200 Message-ID: <4D49738D.7080404@redhat.com> References: <4D484A9B.9040604@siemens.com> <20110202115537.GE14984@redhat.com> <4D4946F7.1070702@siemens.com> <20110202123532.GF14984@redhat.com> <4D4952FA.8020300@siemens.com> <4D49569F.6060207@redhat.com> <4D496A8D.90000@siemens.com> <4D496BC5.10807@redhat.com> <4D496D77.2010405@siemens.com> <4D496FA6.8070301@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Gleb Natapov , kvm , qemu-devel To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:15113 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752279Ab1BBPJI (ORCPT ); Wed, 2 Feb 2011 10:09:08 -0500 In-Reply-To: <4D496FA6.8070301@siemens.com> Sender: kvm-owner@vger.kernel.org List-ID: On 02/02/2011 04:52 PM, Jan Kiszka wrote: > On 2011-02-02 15:43, Jan Kiszka wrote: > > On 2011-02-02 15:35, Avi Kivity wrote: > >> On 02/02/2011 04:30 PM, Jan Kiszka wrote: > >>> On 2011-02-02 14:05, Avi Kivity wrote: > >>>> On 02/02/2011 02:50 PM, Jan Kiszka wrote: > >>>>>>> > >>>>>> Opps, -smp 1. With -smp 2 it boot almost completely and then hangs. > >>>>> > >>>>> Ah, good (or not good). With Windows 2003 Server, I actually get a Blue > >>>>> Screen (Stop 0x000000b8). > >>>> > >>>> Userspace APIC is broken since it may run with an outdated cr8, does > >>>> reverting 27a4f7976d5 help? > >>> > >>> Can you elaborate on what is broken? The way hw/apic.c maintains the > >>> tpr? Would it make sense to compare this against the in-kernel model? Or > >>> do you mean something else? > >> > >> The problem, IIRC, was that we look up the TPR but it may already have > >> been changed by the running vcpu. Not 100% sure. > >> > >> If that is indeed the problem then the fix would be to process the APIC > >> in vcpu context (which is what the kernel does - we set a bit in the IRR > >> and all further processing is synchronous). > > > > You mean: user space changes the tpr value while the vcpu is in KVM_RUN, > > then we return from the kernel and overwrite the tpr in the apic with > > the vcpu's view, right? > > Hmm, probably rather that there is a discrepancy between tpr and irr. > The latter is changed asynchronously /wrt to the vcpu, the former /wrt > the user space device model. And yet, both are synchronized via qemu_mutex. So we're still missing something in this picture. > Run apic_set_irq on the vcpu? static void apic_set_irq(APICState *s, int vector_num, int trigger_mode) { apic_irq_delivered += !get_bit(s->irr, vector_num); trace_apic_set_irq(apic_irq_delivered); set_bit(s->irr, vector_num); This is even more async with kernel irqchip if (trigger_mode) set_bit(s->tmr, vector_num); else reset_bit(s->tmr, vector_num); This is protected by qemu_mutex apic_update_irq(s); This will be run the next time the vcpu exits, via apic_get_interrupt(). } Did you check whether reverting that commit helps? -- error compiling committee.c: too many arguments to function