kvm_gpc_activate_hva
r = kvm_gpc_activate_hva(&kvm->arch.xen.shinfo_cache,
r = kvm_gpc_activate_hva(&vcpu->arch.xen.vcpu_info_cache,
int kvm_gpc_activate_hva(struct gfn_to_pfn_cache *gpc, unsigned long hva, unsigned long len);