CONFIG_KVM_BOOK3S_PR_POSSIBLE is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

CONFIG_KVM_BOOK3S_PR_POSSIBLE (not configurable)

configname: CONFIG_KVM_BOOK3S_PR_POSSIBLE

Linux Kernel Configuration
└─>Virtualization
└─>KVM_BOOK3S_PR_POSSIBLE
In linux kernel since version 3.10 (release Date: 2013-06-30)