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>
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 5bd2f34..74f7319 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -570,6 +570,7 @@
 
 	new = old = *memslot;
 
+	new.id = mem->slot;
 	new.base_gfn = base_gfn;
 	new.npages = npages;
 	new.flags = mem->flags;