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: Thu, 03 Feb 2011 10:18:58 +0200 Message-ID: <4D4A64F2.8010309@redhat.com> References: <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> <4D49738D.7080404@redhat.com> <4D4979BD.6080900@siemens.com> <20110202154611.GR14984@redhat.com> <4D497DAB.7010901@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]:59824 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754043Ab1BCITH (ORCPT ); Thu, 3 Feb 2011 03:19:07 -0500 In-Reply-To: <4D497DAB.7010901@siemens.com> Sender: kvm-owner@vger.kernel.org List-ID: On 02/02/2011 05:52 PM, Jan Kiszka wrote: > >> > > If there is no problem in the logic of this commit (and I do not see > > one yet) then we somewhere miss kicking vcpu when interrupt, that should be > > handled, arrives? > > I'm not yet confident about the logic of the kernel patch: mov to cr8 is > serializing. If the guest raises the tpr and then signals this with a > succeeding, non vm-exiting instruction to the other vcpus, one of those > could inject an interrupt with a higher priority than the previous tpr, > but a lower one than current tpr. QEMU user space would accept this > interrupt - and would likely surprise the guest. Do I miss something? apic_get_interrupt() is only called from the vcpu thread, so it should see a correct tpr. The only difference I can see with the patch is that we may issue a spurious cpu_interrupt(). But that shouldn't do anything bad, should it? -- error compiling committee.c: too many arguments to function