From: Ferruh Yigit <ferruh.yigit@intel.com>
To: Alejandro Lucero <alejandro.lucero@netronome.com>,
Stephen Hemminger <stephen@networkplumber.org>
Cc: Zhe Tao <zhe.tao@intel.com>, dev <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v1] igu_uio: fix IOMMU domain issue
Date: Wed, 11 May 2016 18:24:38 +0100 [thread overview]
Message-ID: <57336AD6.1050809@intel.com> (raw)
In-Reply-To: <CAD+H990mt+5QEN0S0YLfnqBphwjQG3g1kaOeDNZtO+O8GXCOkw@mail.gmail.com>
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 <zhe.tao@intel.com> 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
next prev parent reply other threads:[~2016-05-11 17:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-10 11:21 Zhe Tao
2016-05-10 15:59 ` Stephen Hemminger
2016-05-11 7:35 ` Alejandro Lucero
2016-05-11 17:24 ` Ferruh Yigit [this message]
2016-07-08 17:27 ` Thomas Monjalon
2016-07-09 7:09 ` Ferruh Yigit
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