hw/ppc/spapr.c in QEMU through 3.1.0 allows Information Exposure because the hypervisor shares the /proc/device-tree/system-id and /proc/device-tree/model system attributes with a guest.
Exploitability
AV:LAC:LPR:LUI:NScope
S:UImpact
C:LI:NA:N3.3/CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N