From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35654) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dAqVJ-0006bB-Gn for qemu-devel@nongnu.org; Wed, 17 May 2017 00:24:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dAqVG-0005IG-CT for qemu-devel@nongnu.org; Wed, 17 May 2017 00:24:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46390) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dAqVG-0005Hb-6N for qemu-devel@nongnu.org; Wed, 17 May 2017 00:24:02 -0400 Date: Wed, 17 May 2017 12:23:42 +0800 From: Peter Xu Message-ID: <20170517042342.GA9921@pxdev.xzpeter.org> References: <1494838260-30439-1-git-send-email-peterx@redhat.com> <9a93009b-f909-3142-5bc5-915b9a10ed20@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH 0/4] exec: address space translation cleanups List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Maxime Coquelin Cc: qemu-devel@nongnu.org, Paolo Bonzini , Jason Wang , "Michael S . Tsirkin" , David Gibson On Tue, May 16, 2017 at 06:51:03PM +0200, Maxime Coquelin wrote: > Hi Peter, > > On 05/16/2017 03:24 PM, Maxime Coquelin wrote: > > > > > >On 05/15/2017 10:50 AM, Peter Xu wrote: > >>The problem is that, address_space_get_iotlb_entry() shares a lot with > >>address_space_translate(). This patch tries to abstract the > >>shared elements. > >> > >>Originally, this work is derived from discussion from VT-d passthrough > >>series discussions [1]. But for sure we can just see this series as a > >>standalone cleanup. So I posted it separately here. > >> > >>Smoke tests are done with general VM boots, IOs, especially with vhost > >>dmar configurations. > >> > >>I believe with current series I can throw away the old patch [1], > >>which may be good. But before that, please kindly review. Thanks. > > > >I faced the problem the old patch fixes when declaring and attaching an > >IOMMU device, but booting the kernel with intel_iommu=off. > > > >I tested again with patches 1 & 4 of your series, and I confirm it fixes > >the issue: > >Tested-by: Maxime Coquelin > > I did some more testing with my "vhost-user IOMMU" setup, and the series > actually breaks with IOMMU device attached, and intel_iommu=on. > > The main difference with the previous passing test is the guest RAM > size. In the working setup, it is 2G of 2M hugepages, vs. 4G of 2M > hugepages in the failing one. Note that I also reproduce with vhost-kernel > backend. > > The error happens in the first vhost_device_iotlb_miss() call: > qemu-system-x86_64: Fail to lookup the translated address b5d7c000 > > I don't have the root cause yet, I'll keep you updated. Maxime, Thanks a lot for help testing this series! I reproduced this problem, and this is not a problem obvious enough for me. Let me investigate as well. -- Peter Xu