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You may want to review some documents I've created over the past few years:
I think I understand what it is you are trying to do, however it boils down to the fact that a VF is physically part of a PF. So if your PF is down, so is your VF.
As to the other part of your question - how can a VM know about the bus characteristics of the PF. That kind of functionality is not currently in our drivers - this is by design.
One could add this capability however. Using the mailbox mechanism the VF driver could ask for such information from the PF. The SR-IOV Toolkit (link above) should provide some guidance on how to do this kind of custom messaging.
Best of luck!