Re: [Qemu-ppc] [PATCH qemu v7 06/14] spapr_iommu: Introduce "enabled" state for TCE table

[Alexey Kardashevskiy]

On 05/26/2015 11:48 PM, Paolo Bonzini wrote:
> On 26/05/2015 15:42, Alexey Kardashevskiy wrote:
> > The next patch of this patchset changes:
> > spapr_tce_table_do_enable()
> >      memory_region_init_iommu(&iommu)
> >      memory_region_add_subregion(&root, &iommu)
> >
> > spapr_tce_table_disable()
> >      memory_region_del_subregion(&root, &iommu)
> >      object_unref(&iommu)
> >
> > These spapr_tce_xxx are called by request from the guest. &root is a
> > container and exists as long as sPAPRTCETable exists.
> >
> > Where do I get a leaking child property here?
>
> When you unref iommu and not unparent it.  The next
> memory_region_init_iommu creates a second child property, and the first
> is gone.

But when do I get this child property? In memory_region_add_subregion()? 
And memory_region_del_subregion() does not do the opposite thing (unparent)?


> What is different between the various IOMMU regions, so that you cannot
> create just one?

There are two DMA windows on the same PCI bus (in hardware too), at 
different offset and with a different page size.


--
Alexey