Re: [PATCH 0/6] VIRTIO-IOMMU/VFIO: Revert IOMMUDevice clear and fix hotunplug

["Cédric Le Goater" <clg@redhat.com>]

On 7/16/24 11:45, Eric Auger wrote:
> 1b889d6e39c3 ("virtio-iommu: Clear IOMMUDevice when VFIO
> device is unplugged" fixes the VFIO hotplug/hotunplug/hotplug
> sequence by clearing the IOMMUDevice which backs the VFIO device.
> However this brings other troubles such as a memory corruption.
> 
> Even when fixing some cleanups that were missed on the first
> attempt the memory corruption still exists if the IOMMUDevice is
> freed. Until we understand the exact cause let's make things simpler:
> let the backing IOMMUDevice survive the unplug as what is done
> on intel iommu for instance. Clean up/reset resources that would
> prevent the device from being hotplugged again (probe_done is removed,
> [host_]resv_regions are reset). By doing this we also rule out the
> use case of aliased BDFs which is known to be not functional with
> virtio-iommu (missing guest kernel support) and the virtio-iommu device
> implementation is not ready either.
> 
> This series can be found at:
> https://github.com/eauger/qemu/tree/virtio_iommu_device_clear_fixes_v1
> 
> 
> Eric Auger (6):
>    Revert "virtio-iommu: Clear IOMMUDevice when VFIO device is unplugged"
>    virtio-iommu: Remove probe_done
>    virtio-iommu: Free [host_]resv_ranges on unset_iommu_devices
>    virtio-iommu: Remove the end point on detach
>    hw/vfio/common: Add vfio_listener_region_del_iommu trace event
>    virtio-iommu: Add trace point on
>      virtio_iommu_detach_endpoint_from_domain
> 
>   include/hw/virtio/virtio-iommu.h |  1 -
>   hw/vfio/common.c                 |  3 +-
>   hw/virtio/virtio-iommu.c         | 88 +++++++++++---------------------
>   hw/vfio/trace-events             |  3 +-
>   hw/virtio/trace-events           |  1 +
>   5 files changed, 35 insertions(+), 61 deletions(-)
> 


Tested-by: Cédric Le Goater <clg@redhat.com>

with a vfio-pci device (mlx5 VF) and a virtio-net-pci device.

Thanks,

C.