KVM: introduce id_to_memslot function

Introduce id_to_memslot to get memslot by slot id

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 392af47..123925c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -333,6 +333,12 @@
 			|| lockdep_is_held(&kvm->slots_lock));
 }
 
+static inline struct kvm_memory_slot *
+id_to_memslot(struct kvm_memslots *slots, int id)
+{
+	return &slots->memslots[id];
+}
+
 #define HPA_MSB ((sizeof(hpa_t) * 8) - 1)
 #define HPA_ERR_MASK ((hpa_t)1 << HPA_MSB)
 static inline int is_error_hpa(hpa_t hpa) { return hpa >> HPA_MSB; }