Comment 7 for bug 1769053

You don't need a >1TB host to spin up a >1TB guest. Unless you're using pci passthru (and/or SRIOV), or something else that requires qemu to alloc and pin all guest mem, you can simply overcommit; normal guests don't require mem pre-allocation or pinning.

On your host do this to allow overcommitting such a large amount (this allows 16T but can be adjusted as needed):

$ echo $[ 16 * 1024 * 1024 * 1024 ] | sudo tee /proc/sys/vm/overcommit_kbytes
17179869184
$ echo 1 | sudo tee /proc/sys/vm/overcommit_memory
1

Then just virsh edit your guest to use >1TB, e.g.:

  <memory unit='GiB'>1500</memory>

And of course, stop and restart the guest to pick up the xml change.