[libvirt] libvirt mdev migration, mdevctl integration

[Boris Fiuczynski]

On 11/25/19 6:14 PM, Cornelia Huck wrote:
> Also, I'm wondering if we need special care for vfio-ap, although I'm
> not sure if it is feasible to add migration support for it all. We
> currently have a matrix device (always same parent) defined by the
> UUID, and adapters/domains configured for this matrix device (which is
> handled as extra parameters in the mdevctl device config). I'm not sure
> how different adapters/domains translate between systems we want to
> migrate between. Not sure how much sense it makes to dwell on this at
Aside from the card preparation with the appropriate masterkeys the 
adapter/domain configuration (including the card types) for an mdev 
needs to remain the same since there is no virtualization of 
adapter/domain addresses in the current vfio-ap driver implementation. 
As a result a currently possible migration scenario is cross-CEC.

 From libvirts perspective:
Assuming that mdevs on the source and target system exist, would a 
matching UUID be enough assurance that these two host resources match 
for a migration? If not, is a check performed on the configuration of 
the two mdevs? What is in that case considered migration save? Where are 
these checks implemented? Does the checking for migratablity go beyond 
the configuration data of mdev devices, e.g. vfio-ap: check for 
existence of masterkeys, card type equivalency or as Connie mentioned 
before on vfio-ccw the equivalency of the child ccw device of the 
subchannels.

> the moment, though; but IIRC, there were some pci devices wanting to
> use extra parameters as well (and there was also that discussion about
> how to support aggregation).


-- 
Mit freundlichen Grüßen/Kind regards
    Boris Fiuczynski

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