HiSuspend-to-ram and resume stopped working on v4.15-rc1 and I bisected it to commit ca37e57bbe0c ("x86/entry/64: Add missing irqflags tracing to native_load_gs_index()").
I noticed it on Intel Kabylake (core) and Apollolake (atom) based prototype machines. Symptoms are that machine appears to enter into suspend but resumes instantly and hangs. Unfortunately no logs.
If I revert ca37e57bbe0c on v4.15-rc1 it works as expected. -- Jarkko