Re: [PATCH 0/4] Fix splats releated to using the iommu_group after destroying devices

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, Sep 09, 2022 at 08:49:40AM -0400, Matthew Rosato wrote:
> On 9/8/22 2:44 PM, Jason Gunthorpe wrote:
> > The basic issue is that the iommu_group is being used by VFIO after all
> > the device drivers have been removed.
> > 
> > In part this is caused by bad logic inside the iommu core that doesn't
> > sequence removing the device from the group properly, and in another part
> > this is bad logic in VFIO continuing to use device->iommu_group after all
> > VFIO device drivers have been removed.
> > 
> > Fix both situations. Either fix alone should fix the bug reported, but
> > both together bring a nice robust design to this area.
> > 
> > This is a followup from this thread:
> > 
> > https://lore.kernel.org/kvm/20220831201236.77595-1-mjrosato@linux.ibm.com/
> > 
> > Matthew confirmed an earlier version of the series solved the issue, it
> > would be best if he would test this as well to confirm the various changes
> > are still OK.
> 
> FYI I've been running this series (+ the incremental to patch 4 you
> mentioned) against my original repro scenario in a loop overnight,
> looks good.

Thanks Matthew, looks like we need some more time on the last patch
but I think the VFIO ones are OK if Alex wants to pick them before LPC
is over.

Jason