KVM: Keep slot ID in memory slot structure

May be used for distinguishing between internal and user slots, or for sorting
slots in size order.
Signed-off-by: Avi Kivity <avi@redhat.com>

include/linux/kvm_host.h

@@ -124,6 +124,7 @@ struct kvm_memory_slot {
 	} *lpage_info[KVM_NR_PAGE_SIZES - 1];
 	unsigned long userspace_addr;
 	int user_alloc;
+	int id;
 };
 
 static inline unsigned long kvm_dirty_bitmap_bytes(struct kvm_memory_slot *memslot)

virt/kvm/kvm_main.c

@@ -570,6 +570,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 
 	new = old = *memslot;
 
+	new.id = mem->slot;
 	new.base_gfn = base_gfn;
 	new.npages = npages;
 	new.flags = mem->flags;