[nialv7]

L0 is only used by speculatively executed uOPs, before they are actually committed. Therefore anything that reads from L0 has to be speculatively executed too.

So if the uOP populated the L0 was reading from kernel memory, then it won't be committed. And subsequent uOP read from the L0 won't be committed either. So you can't get timing information from them.

[foota]

But if another instruction reads from the same cache then that one could retire.