Are all these really need? According to this https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux... to me sounds like only "mitigations=off" is the one is needed, no?

By checking sysfs reporting, the mitigations=off and all those from URL above ends up in same results.

PRs accepted : https://github.com/jcelerier/jcelerier.github.io/blob/master...

:-)

The title makes me want to up-vote but when I click through the link all I see is "noibrs noibpb nopti nospectre_v2 nospectre_v1 l1tf=off nospec_store_bypass_disable no_stf_barrier mds=off mitigations=off"

It's the kernel flags that you use for disabling all the Spectre/Meltdown/whatever mitigations that are slowing Linux down by a lot.

For single-user computers this is a useful and sensible option.

Be aware of web browsers though.

These are just kernel flags - the interested will understand.

Well would also love more explanation, but it kind of seems enough

How much will I gain on my desktop if I set those? What do they do individually?

To what kernel release(s) do the flags apply?

Need to check in your distro kernel. For example, current kernel on Linux Mint (is Ubuntu based distro, so I guess Ubuntu as well) has this changelog: http://changelogs.ubuntu.com/changelogs/pool/main/l/linux/li... and as you see, it is backported and supported.