[PATCH kernel] KVM: PPC: Release all hardware TCE tables attached to a group

[Paul Mackerras]

On Tue, Feb 12, 2019 at 03:37:45PM +1100, Alexey Kardashevskiy wrote:
> The SPAPR TCE KVM device references all hardware IOMMU tables assigned to
> some IOMMU group to ensure that in-kernel KVM acceleration of H_PUT_TCE
> can work. The tables are references when an IOMMU group gets registered
> with the VFIO KVM device by the KVM_DEV_VFIO_GROUP_ADD ioctl;
> KVM_DEV_VFIO_GROUP_DEL calls into the dereferencing code
> in kvm_spapr_tce_release_iommu_group() which walks through the list of
> LIOBNs, finds a matching IOMMU table and calls kref_put() when found.
> 
> However that code stops after the very first successful derefencing
> leaving other tables referenced till the SPAPR TCE KVM device is destroyed
> which normally happens on guest reboot or termination so if we do hotplug
> and unplug in a loop, we are leaking IOMMU tables here.
> 
> This removes a premature return to let kvm_spapr_tce_release_iommu_group()
> find and dereference all attached tables.
> 
> Fixes: 121f80ba68f "KVM: PPC: VFIO: Add in-kernel acceleration for VFIO"
> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>

Thanks, applied to my kvm-ppc-next tree.

Paul.