Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture

[Gerd Hoffmann]

  Hi,

> > If we can somehow make a *trustable* physbits value available to the
> > guest, then yes, we can go that route.  But the guest physbits we have
> > today unfortunately don't cut it.
> 
> In downstream RH qemu, we run with host-physbits as default; so it's 
> reasonably
> trustworthy;

Can the guest figure somehow whenever it is trustworthy or not?

> of course that doesn't help you across a migration between
> hosts with different sizes (e.g. an E5 Xeon to an E3).

Making physbits configurable for migration compatibility is fine if qemu
outlaws the problematic guest physbits > host physbits case and throws
an error in that case.

take care,
  Gerd