From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: Lost interrupts with upstream KVM Date: Fri, 29 May 2009 18:46:47 +0200 Message-ID: <4A201177.2090103@siemens.com> References: <4A1F9B7C.4020201@siemens.com> <20090529130806.GB28542@redhat.com> <4A1FF6B9.9050502@siemens.com> <20090529162015.GA29579@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: kvm-devel , qemu-devel To: Gleb Natapov Return-path: Received: from lizzard.sbs.de ([194.138.37.39]:18291 "EHLO lizzard.sbs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752810AbZE2QrR (ORCPT ); Fri, 29 May 2009 12:47:17 -0400 In-Reply-To: <20090529162015.GA29579@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Gleb Natapov wrote: > On Fri, May 29, 2009 at 04:52:41PM +0200, Jan Kiszka wrote: >> Gleb Natapov wrote: >>> On Fri, May 29, 2009 at 10:23:24AM +0200, Jan Kiszka wrote: >>>> Hi Gleb, >>>> >>>> with latest kernel modules, namely beginning with 6bc0a1a235 (Remove >>>> irq_pending bitmap), I'm loosing interrupts with upstream's KVM support. >>>> After some bisecting, hair-pulling and a bit meditation I added a >>>> WARN_ON(kvm_cpu_has_interrupt(vcpu)) to kvm_vcpu_ioctl_interrupt, and it >>>> actually triggered right before the guest got stuck. >>>> >>>> This didn't trigger with qemu-kvm (and -no-kvm-irqchip) yet but, on the >>>> other hand, I currently do not see a potential bug in upstream's >>>> kvm_arch_pre_run. Could you have a look if you can reproduce, >>>> specifically if this isn't a KVM kernel issue in the end? >>>> >>> In kvm_cpu_exec() after calling kvm_arch_pre_run() env->exit_request is >>> tested and function can exit without calling kvm_vcpu_ioctl(KVM_RUN). >>> Can you check if this what happens in your case? >> This path is executed quite frequently here. No obvious correlation with >> the lost IRQ. >> > If kvm_arch_pre_run() injected interrupt kvm_vcpu_ioctl(KVM_RUN) have to > be executed before injecting another interrupt, so if on the fist call > of kvm_cpu_exec() kvm_arch_pre_run() injected interrupt, but > kvm_vcpu_ioctl(KVM_RUN) was not executed because of env->exit_request > and on the next kvm_cpu_exec() other interrupt is injected the previous > one will be lost. ...and kvm_run->ready_for_interrupt_injection is not updated either in that case, right? That makes be wonder if KVM_INTERRUPT shouldn't better return an error in case the queue is full already. Jan -- Siemens AG, Corporate Technology, CT SE 2 Corporate Competence Center Embedded Linux