On Thu, Sep 22, 2022 at 7:13 PM Jim Mattson <jmattson@xxxxxxxxxx> wrote: > > Treating 40 as invalid and continue to use the current conservative > > heuristic, otherwise treat phys-bits as valid might work. Obvious > > corner case is that it'll not catch broken manual configurations > > (host-phys-bits=off,phys-bits=<larger-than-host>), only the broken > > default. Not sure how much of a problem that is in practice, maybe > > it isn't. > > > > I think I still prefer to explicitly communicate a reliable phys-bits > > value to the guest somehow. > > On x86 hardware, KVM is incapable of emulating a guest physical width > that differs from the host physical width. There isn't support in the > hardware for it. Indeed, everything else is a userspace bug. Especially since here we're talking of host_maxphyaddr < guest_maxphyaddr, which is completely impossible. Paolo
