From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Monjalon Subject: Re: [PATCH v1] igu_uio: fix IOMMU domain issue Date: Fri, 08 Jul 2016 19:27:36 +0200 Message-ID: <2574807.bEb98RZhNN@xps13> References: <1462879301-13570-1-git-send-email-zhe.tao@intel.com> <57336AD6.1050809@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: dev@dpdk.org, Ferruh Yigit , Alejandro Lucero , Stephen Hemminger To: Zhe Tao Return-path: Received: from mail-wm0-f48.google.com (mail-wm0-f48.google.com [74.125.82.48]) by dpdk.org (Postfix) with ESMTP id 85F7DAD80 for ; Fri, 8 Jul 2016 19:27:38 +0200 (CEST) Received: by mail-wm0-f48.google.com with SMTP id k123so18608011wme.0 for ; Fri, 08 Jul 2016 10:27:38 -0700 (PDT) In-Reply-To: <57336AD6.1050809@intel.com> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Ping, this patch is stalled. 2016-05-11 18:24, Ferruh Yigit: > On 5/11/2016 8:35 AM, Alejandro Lucero wrote: > > On Tue, May 10, 2016 at 4:59 PM, Stephen Hemminger < > > stephen@networkplumber.org> wrote: > > > >> On Tue, 10 May 2016 19:21:41 +0800 > >> Zhe Tao wrote: > >> > >>> Problem: > >>> The following operations will cause the igb_uio based DPDK > >>> operation failed. > >>> --Any device assignment through the kvm_assign_device interface, > >>> this can be the pci-assign method in QEMU > >>> --VFIO group attachment operation(attach to the container) > >>> this can happens in vfio-pci assignment in QEMU > >> > >> > >> If you have an IOMMU why not use VFIO instead, it is better. > >> > > > > It is not about VFIO against UIO but about how iommu domains are created > > and destroyed by the (old) kernel when iommu=pt. So even with VFIO you can > > have problems. > > Problem is in IOMMU driver but we are adding a workaround to igb_uio, if > using VFIO solves the issue, I believe that is better workaround. > > 1) Is there any case IOMMU supported but VFIO is not supported? Is there > anything forces to use igb_uio? > > 2) Does using VFIO solves the issue defined in problem statement? > > > > > We have had problems like this and other due to our device (NFP) just > > mapping up to 40 bits of address space. Old kernels used in LTS > > distributions like Ubuntu are iommu buggy and you need to do things like > > this mapping inside the driver for solving problems. By the way, using > > SRIOV just adds more problems. It is not safe to use iommu=pt with 3.13.x > > Ubuntu kernels. > > > > It would be a good thing for the original patch to identify those kernels > > where the problem was detected. Of course, there could be more kernels with > > the same problem but that is more work to do. > > > > Thanks, > ferruh