is there any publicly available list of these undocumented inputs?

been measuring cpuid execution with random input and with input zero, when eax is zero, cpuid takes ~57 cycles, and with random eax, it varies, from 100 cycles to 500 cycles.

I'm sure somebody already tried to figure out all of this, but google is so biased and useless.

http://instlatx64.atw.hu/
... is the long term canonical source of CPUID dumps; but I'm not sure that is what you are looking for? Some people want to emulate a particular CPU down to the exact CPUID info and these dumps are invaluable in this regard.

no, not that; impressive per core dump, wondering if certain core can spit more info than other

I tried to search google and ddg, but non showing what I want.
probably nobody figured out undocumented cpuid fields.

I assume you have read chapter 21 of the excellent Intel® 64 and IA-32 Architectures Software Developer Manuals, which was last updated in October 2025. Is that insufficient?

Available on that link:
https://www.intel.com/content/www/us/en/developer/articles/technical/intel-sdm.html

Edit by revolution: Update link to final destination. URL shorteners, and link share sites, hide information and act as gatekeepers.

The interface is very dense, but SIV probably has more information in one place than any other tool I know. Discovery is fun and so many metrics are collected by hardware. The author definitely did not leave out CPUID: right-click on the title-bar, menu: Hardware > CPUID > CPU-#

The information is readable - from a low-level and high-level perspective. Unknown regions are also displayed.