I was curious myself, poked around, and found some references. But I'm still woefully incapable of answering that with any confidence and don't want to risk saying anything misleading, so here's the code and some other breadcrumbs:

1. Apparently OpenBSD gave up on trying to fix desync'd TSCs. See https://github.com/openbsd/src/commit/78156938567f79506a923c...

2. Relevant OpenBSD kernel code: https://github.com/openbsd/src/blob/master/sys/arch/amd64/am...

3. Relevant Linux kernel code: https://github.com/torvalds/linux/blob/master/arch/x86/kerne..., https://github.com/torvalds/linux/blob/master/arch/x86/kerne...

4. Linux kernel doc (out-of-date?): https://www.kernel.org/doc/Documentation/virtual/kvm/timekee...

5. Detailed SUSE blog post with many links: https://www.suse.com/c/cpu-isolation-nohz_full-troubleshooti...

6. Linux patch (uncommitted?) to attempt to directly sync TSCs: https://lkml.rescloud.iu.edu/2208.1/00313.html