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 <maxime.coque...@redhat.com> > > 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
