Re: [Qemu-devel] [PATCH qemu v8 06/14] spapr_iommu: Introduce "enabled" state for TCE table

[David Gibson]

On Thu, Jun 18, 2015 at 09:37:28PM +1000, Alexey Kardashevskiy wrote:
> Currently TCE tables are created once at start and their size never
> changes. We are going to change that by introducing a Dynamic DMA windows
> support where DMA configuration may change during the guest execution.
> 
> This changes spapr_tce_new_table() to create an empty stub object. Only
> LIOBN is assigned by the time of creation. It still will be called once
> at the owner object (VIO or PHB) creation.
> 
> This introduces an "enabled" state for TCE table objects with two
> helper functions - spapr_tce_table_enable()/spapr_tce_table_disable().
> spapr_tce_table_enable() receives TCE table parameters and allocates
> a guest view of the TCE table (in the user space or KVM).
> spapr_tce_table_disable() disposes the table.
> 
> Follow up patches will disable+enable tables on reset (system reset
> or DDW reset).
> 
> No visible change in behaviour is expected except the actual table
> will be reallocated every reset. We might optimize this later.
> 
> The other way to implement this would be dynamically create/remove
> the TCE table QOM objects but this would make migration impossible
> as migration expects all QOM objects to exist at the receiver
> so we have to have TCE table objects created when migration begins.
> 
> spapr_tce_table_do_enable() is separated from from spapr_tce_table_enable()
> as later it will be called at the sPAPRTCETable post-migration stage when
> it has all the properties set after the migration.
> 
> Signed-off-by: Alexey Kardashevskiy <address@hidden>
> ---
> Changes:
> v8:
> * add missing unparent_object() to spapr_tce_table_unrealize() (parenting
> is made by memory_region_init_iommu)

Um.. I don't see an unparent_object() in spapr_tce_table_unrealize().
Or anywhere else.  I don't actually know where it's necessary, but
this seems to contracdict your changelog regardless.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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