CONFIG_KVM_BOOK3S_PR is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

CONFIG_KVM_BOOK3S_PR (not configurable)

configname: CONFIG_KVM_BOOK3S_PR

Linux Kernel Configuration
└─>Virtualization
└─>KVM_BOOK3S_PR
In linux kernel since version 3.1 (release Date: 2011-10-24)  
selects
CONFIG_KVM_MMIO


is depended by
CONFIG_KVM_BOOK3S_64_PR