From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] KVM: SVM: fix random segfaults with NPT enabled Date: Wed, 27 Aug 2008 18:21:40 +0300 Message-ID: <48B57104.7060001@qumranet.com> References: <1219839523-25677-1-git-send-email-joerg.roedel@amd.com> <48B55266.4000300@qumranet.com> <20080827135326.GB26059@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, stable@kernel.org, Alexander Graf To: Joerg Rodel Return-path: Received: from il.qumranet.com ([212.179.150.194]:43912 "EHLO il.qumranet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753266AbYH0PVm (ORCPT ); Wed, 27 Aug 2008 11:21:42 -0400 In-Reply-To: <20080827135326.GB26059@amd.com> Sender: kvm-owner@vger.kernel.org List-ID: Joerg Rodel wrote: >> hm. tbench doesn't allocate memory, so there shouldn't be any npt faults. I don't >> see how this can make a difference. >> > > I reproduced it. There are a few npt faults as the guest has not touched all of memory yet. If I force it to touch all of memory (dd < /dev/hda), the problem appears to go away. > Base for the fix was this bugreport: > > http://sourceforge.net/tracker/index.php?func=detail&aid=2019053&group_id=180599&atid=893831 > > We found out that the same crash occur on long running compile > workloads and that stale tlb-entries cause it. Until we find the real > location of the missing tlb flush in the mmu code, i think its best to > flush the TLB every time the mapping/unmapping code for the nested page > table is executed. This fixes at least the crashes in the guest and has > only minimal performance impact. > I'd like to try and find out what the problem is exactly. Otherwise we may be only narrowing the window, not closing it. -- error compiling committee.c: too many arguments to function