RE: [PATCH 06/18] x86, barrier: stop speculation for failed access_ok

David Laight
2018-01-08T11:59:53Z

From: Linus Torvalds
> Sent: 07 January 2018 19:47
...
> Also, people definitely *are* noticing the performance issues with the
> current set of patches, and they are causing real problems. Go search
> for reports of Amazon AWS slowdowns.

Try over 35% slowdown....
Given that AWS instance runs known code (user and kernel) why do we
need to worry about any of these sideband attacks?

David