Re: [dpdk-dev] [PATCH dpdk 4/5] vfio: Do try setting IOMMU type if already set

[Alejandro Lucero <alejandro.lucero@netronome.com>]

On Wed, Apr 26, 2017 at 9:58 AM, Burakov, Anatoly <anatoly.burakov@intel.com
> wrote:

> Hi Alejandro,
>
> > I was counting on first submitted patch being accepted.
>
> OK, that's on me then.
>
> > There is another thing to solve which is to unplug ports when there are
> more than one (already plugged) in an IOMMU group. I have a patch for this
> but I can not test it for that scenario, just for the "normal" one with one
> port/device per IOMMU group. > I'm working on having a way for testing the
> first case.
>
> Have you tried older kernel versions yet? Those seem to work for me.
>
>
I'm trying that one but run in some problems. Likely that is the quickest
way although I'm thinking on adding some option to the kernel for people
with such a hardware being able to test that option.



> > The only problem is after that, none else device hotplug can happen. I
> know that is not a good thing because it requires to restart the app, but
> better than breaking the app with a crash.
>
> Presumably, you're only talking about VFIO hotplug, and not hotplug in
> general? Is there anything that can be done to fix this issue in the long
> run?
>
>

Yes, just talking about VFIO. I think that patch I have should solve the
issue. It is just a matter of tracking how many devices are in use on a
vfio group, so just adding a new field to struct vfio_group and checking
number of devices when unplugging should be enough. Just when is the only
device plugged should close the vfio group.


> Thanks,
> Anatoly
>
>