Comment 4 for bug 1493049

There is no memory_region_get_dirty_log_mask in the 2.0.0, this was only introduced later. Strictly speaking, 2.0.0 is quite different from 2.4.0 in this matter but I checked the code logic here and it should be good.

Yes, I was not sure what versions it affects so I only referenced Trusty. If this affects anything else please make appropriate edits.