From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Zhang Haoyu" Subject: Re: [question] e1000 interrupt storm happened becauseof its corresponding ioapic->irr bit always set Date: Mon, 25 Aug 2014 15:17:27 +0800 Message-ID: <201408251517235889695@sangfor.com> References: <201408231836387399956@sangfor.com>, <53FAA874.70703@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="gb2312" Content-Transfer-Encoding: 7bit To: "Jason Wang" , "qemu-devel" , "kvm" Return-path: Received: from smtp.sanfor.com ([58.251.49.30]:57785 "EHLO mail.sangfor.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1754490AbaHYHTv (ORCPT ); Mon, 25 Aug 2014 03:19:51 -0400 Sender: kvm-owner@vger.kernel.org List-ID: >> 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). > Thanks, Jason, I searched "e1000 autoneg" in gmane.comp.emulators.qemu, and found below patches, http://thread.gmane.org/gmane.comp.emulators.qemu/143001/focus=143007 http://thread.gmane.org/gmane.comp.emulators.qemu/284105/focus=284765 http://thread.gmane.org/gmane.comp.emulators.qemu/186159/focus=187351 which one tries to fix this problem, or all of them? >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. > Sorry, I don't understand, I think one interrupt should not been enabled before its handler is successfully registered, is it possible that e1000 emulation inject the interrupt before the interrupt is succesfully enabled? Thanks, Zhang Haoyu >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 >> >> From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50283) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XLoZK-0004mo-TR for qemu-devel@nongnu.org; Mon, 25 Aug 2014 03:20:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XLoZF-0000X6-Ca for qemu-devel@nongnu.org; Mon, 25 Aug 2014 03:19:58 -0400 Received: from [58.251.49.30] (port=38876 helo=mail.sangfor.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XLoZE-0000WV-UI for qemu-devel@nongnu.org; Mon, 25 Aug 2014 03:19:53 -0400 Date: Mon, 25 Aug 2014 15:17:27 +0800 From: "Zhang Haoyu" References: <201408231836387399956@sangfor.com>, <53FAA874.70703@redhat.com> Message-ID: <201408251517235889695@sangfor.com> Mime-Version: 1.0 Content-Type: text/plain; charset="gb2312" Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [question] e1000 interrupt storm happened becauseof its corresponding ioapic->irr bit always set List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jason Wang , qemu-devel , kvm >> 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). > Thanks, Jason, I searched "e1000 autoneg" in gmane.comp.emulators.qemu, and found below patches, http://thread.gmane.org/gmane.comp.emulators.qemu/143001/focus=143007 http://thread.gmane.org/gmane.comp.emulators.qemu/284105/focus=284765 http://thread.gmane.org/gmane.comp.emulators.qemu/186159/focus=187351 which one tries to fix this problem, or all of them? >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. > Sorry, I don't understand, I think one interrupt should not been enabled before its handler is successfully registered, is it possible that e1000 emulation inject the interrupt before the interrupt is succesfully enabled? Thanks, Zhang Haoyu >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 >> >>