From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: Remaining passthrough/VT-d tasks list Date: Sun, 28 Sep 2008 08:04:06 +0300 Message-ID: <48DF1046.1050102@redhat.com> References: <0122C7C995D32147B66BF4F440D3016301C49E61@pdsmsx415.ccr.corp.intel.com> <200809241431.13571.sheng.yang@intel.com> <48D9FC8B.2040902@redhat.com> <200809271715.54439.sheng.yang@intel.com> <48DE01AB.2050303@redhat.com> <48DF069D.90004@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=GB2312 Content-Transfer-Encoding: 7bit Cc: "Yang, Sheng" , "Han, Weidong" , "kvm@vger.kernel.org" , Amit Shah , "benami@il.ibm.com" , "muli@il.ibm.com" , "Kay, Allen M" , "Zhang, Xiantao" To: "Tian, Kevin" Return-path: Received: from mx2.redhat.com ([66.187.237.31]:51818 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750911AbYI1FEg (ORCPT ); Sun, 28 Sep 2008 01:04:36 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: Tian, Kevin wrote: >> >> No. Maybe the Neocleus polarity trick (which also reduces performance). >> > > To my knowledge, Neocleus polarity trick can't solve this isolation > issue, which just provides one effecient way to track assertion/deassertion > transition on the irq line. For example, reverse polarity when receiving an > instance, and then a new irq instance would occur when all devices de- > assert on shared irq line, and then recover the polarity. In your concerned > case where guest driver misbehaves, this polarity trick can't work neither > as one device always asserts the line. > You're right, I didn't think it through. If there was a standard way to mask pci irqs, it might have worked, but there isn't, unfortunately. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.