From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [Qemu-devel] [question] e1000 interrupt storm happened because of its corresponding ioapic->irr bit always set Date: Mon, 25 Aug 2014 11:07:32 +0800 Message-ID: <53FAA874.70703@redhat.com> References: <201408231836387399956@sangfor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit To: Zhang Haoyu , qemu-devel , kvm Return-path: Received: from mx1.redhat.com ([209.132.183.28]:37146 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753826AbaHYDHl (ORCPT ); Sun, 24 Aug 2014 23:07:41 -0400 In-Reply-To: <201408231836387399956@sangfor.com> Sender: kvm-owner@vger.kernel.org List-ID: On 08/23/2014 06:36 PM, Zhang Haoyu wrote: > Hi, all > > I use a qemu-1.4.1/qemu-2.0.0 to run win7 guest, and encounter e1000 NIC interrupt storm, > because "if (!ent->fields.mask && (ioapic->irr & (1 << i)))" is always true in __kvm_ioapic_update_eoi(). > > Any ideas? We meet this several times: search the autoneg patches for an example of workaround for this in qemu, and patch kvm: ioapic: conditionally delay irq delivery during eoi broadcast for an workaround in kvm (rejected). That was probably caused by something wrong in e1000 emulation which causes interrupt to be injected into windows guest before its interrupt handler is registered. And Windows guest does not have a mechanism to detect and disable irq in such condition. e1000 emulation is far from stable and complete (e.g run e1000 ethtool selftest in linux guest may see lots of errors). It's complicate and subtle (even has undocumented registers and behaviour). You should better consider to use virtio which are more stable and fast in a kvm guest (unless some intel guys are involved to improve e1000 emulation). Thanks > > Thanks, > Zhang Haoyu > >