Re: [RFC PATCH] iommu/vt-d: Fix IOMMU field not populated on device hot re-plug

[Lu Baolu]

Hi,

On 10/1/19 11:01 PM, Janusz Krzysztofik wrote:
> Hi Baolu,
>
> On Tuesday, September 3, 2019 9:41:23 AM CEST Janusz Krzysztofik wrote:
> > Hi Baolu,
> >
> > On Tuesday, September 3, 2019 3:29:40 AM CEST Lu Baolu wrote:
> > > Hi Janusz,
> > >
> > > On 9/2/19 4:37 PM, Janusz Krzysztofik wrote:
> > > > > I am not saying that keeping data is not acceptable. I just want to
> > > > > check whether there are any other solutions.
> > > > Then reverting 458b7c8e0dde and applying this patch still resolves the
> > issue
> > > > for me.  No errors appear when mappings are unmapped on device close after
> > the
> > > > device has been removed, and domain info preserved on device removal is
> > > > successfully reused on device re-plug.
> > >
> > > This patch doesn't look good to me although I agree that keeping data is
> > > acceptable.
>
> Any progress with that?  Which mailing list should I watch for updates?\

We had a holiday last week. I will go ahead with reproducing it locally.
Feel free to let me know if you have any new proposal.

Best regards,
Baolu

> Thanks,
> Janusz
>
> > > It updates dev->archdata.iommu, but leaves the hardware
> > > context/pasid table unchanged. This might cause problems somewhere.
> > >
> > > > Is there anything else I can do to help?
> > >
> > > Can you please tell me how to reproduce the problem?
> >
> > The most simple way to reproduce the issue, assuming there are no non-Intel
> > graphics adapters installed, is to run the following shell commands:
> >
> > #!/bin/sh
> > # load i915 module
> > modprobe i915
> > # open an i915 device and keep it open in background
> > cat /dev/dri/card0 >/dev/null &
> > sleep 2
> > # simulate device unplug
> > echo 1 >/sys/class/drm/card0/device/remove
> > # make the background process close the device on exit
> > kill $!
> >
> > Thanks,
> > Janusz
> >
> >
> > > Keeping the per
> > > device domain info while device is unplugged is a bit dangerous because
> > > info->dev might be a wild pointer. We need to work out a clean fix.
> > >
> > > > Thanks,
> > > > Janusz
> > >
> > > Best regards,
> > > Baolu