Re: [PATCH 0/3] Allow the group FD to remain open when unplugging a device

[Alex Williamson <alex.williamson@redhat.com>]

On Thu,  6 Oct 2022 09:40:35 -0300
Jason Gunthorpe <jgg@nvidia.com> wrote:

> Testing has shown that virtnodedevd will leave the group FD open for long
> periods, even after all the cdevs have been destroyed. This blocks
> destruction of the VFIO device and is undesirable.
> 
> That approach was selected to accomodate SPAPR which has an broken
> lifecyle model for the iommu_group. However, we can accomodate SPAPR by
> realizing that it doesn't use the iommu core at all, so rules about
> iommu_group lifetime do not apply to it.
> 
> Giving the KVM code its own kref on the iommu_group allows the VFIO core
> code to release its iommu_group reference earlier and we can remove the
> sleep that only existed for SPAPR.
> 
> Jason Gunthorpe (3):
>   vfio: Add vfio_file_is_group()
>   vfio: Hold a reference to the iommu_group in kvm for SPAPR
>   vfio: Make the group FD disassociate from the iommu_group
> 
>  drivers/vfio/pci/vfio_pci_core.c |  2 +-
>  drivers/vfio/vfio.h              |  1 -
>  drivers/vfio/vfio_main.c         | 90 +++++++++++++++++++++-----------
>  include/linux/vfio.h             |  1 +
>  virt/kvm/vfio.c                  | 45 +++++++++++-----
>  5 files changed, 94 insertions(+), 45 deletions(-)

Containers aren't getting cleaned up with this series, starting and
shutting down a libvirt managed VM with vfio-pci devices, an mtty mdev
device, and making use of hugepages, /proc/meminfo shows the hugepages
are not released on VM shutdown and I'm unable to subsequently restart
the VM. Thanks,

Alex