KVM: x86: Free arrays for old memslot when moving memslot's base gfn

Explicitly free the metadata arrays (stored in slot->arch) in the old
memslot structure when moving the memslot's base gfn is committed.  This
eliminates x86's dependency on kvm_free_memslot() being called when a
memslot move is committed, and paves the way for removing the funky code
in kvm_free_memslot() that conditionally frees structures based on its
@dont param.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/x86.c

@@ -10066,6 +10066,10 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
 	 */
 	if (change != KVM_MR_DELETE)
 		kvm_mmu_slot_apply_flags(kvm, (struct kvm_memory_slot *) new);
+
+	/* Free the arrays associated with the old memslot. */
+	if (change == KVM_MR_MOVE)
+		kvm_arch_free_memslot(kvm, old, NULL);
 }
 
 void kvm_arch_flush_shadow_all(struct kvm *kvm)