[PATCH v3 0/2] VFIO mdev aggregated resources handling

[Yan Zhao]

On Wed, Jul 08, 2020 at 11:38:46AM +0800, Yan Zhao wrote:
> On Wed, Jul 08, 2020 at 09:54:19AM +0800, Zhenyu Wang wrote:
> > On 2020.07.07 19:06:34 -0600, Alex Williamson wrote:
> > > On Tue, 7 Jul 2020 23:28:39 +0000
> > > "Tian, Kevin" <kevin.tian at intel.com> wrote:
> > > 
> > > > Hi, Alex, 
> > > > 
> > > > Gentle ping... Please let us know whether this version looks good.
> > > 
> > > I figured this is entangled with the versioning scheme.  There are
> > > unanswered questions about how something that assumes a device of a
> > > given type is software compatible to another device of the same type
> > > handles aggregation and how the type class would indicate compatibility
> > > with an aggregated instance.  Thanks,
> > > 
> > 
> > +Yan
> > 
> > Alex, If no concern on aggregated resources info for instance that would
> > be vendor's behavior to determine what type of resources would be aggregated,
> > then I'll check with Yan to see how to fulfill this during migration.
> > 
> > Thanks
> >
> 
> hi zhenyu and Alex
> currently in this series, it looks that aggregated instances are created
> in this way:
>     echo "<uuid>,aggregate=10" > create
> 
> Is that possible that we change it like that:
> 1. provide a separate attribute named "aggregator" under mdev type.
>   |- [parent physical device]
>   |--- Vendor-specific-attributes [optional]
>   |--- [mdev_supported_types]
>   |     |--- [<type-id>]
>   |     |   |--- create
> + |     |   |--- aggregator
>   |     |   |--- name
>   |     |   |--- available_instances
>   |     |   |--- device_api
>   |     |   |--- description
>   |     |   |--- [devices]
> 
> normally, the aggregator is read as 0.
>
correction: normally, the aggregator is read as "1"

> 2. when we want to create an aggregated instance, we first echo the count
> into the aggregator attribute. e.g.
>    echo 10 > aggregator
> It will switch the mdev type to 10 x original_type. And then,
> available_instances and description would be updated accordingly.
> 
> 3. do the real mdev creation.
>    echo <uuid> > create
> 
> 
> In this way, before any instance is created, we can use the
> migration_version attribute to test if two aggregation mdevs are
> migration compatible.
> 
> Thanks
> Yan
> 
>