The restriction on MSR writes from the kernel people is just nuts. It's like they are saying: we know better, you're stupid and shouldn't be doing this so we just won't let you.
I'm still fuming.
I'm still fuming.
Writes to arbitrary MSR are still allowed by linux, but it'll squawk a warning with the PID from what poked the MSR. What has been preventing writing to MSR is microcode updates (loaded via Linux via initram/firmware, or via the vendor in a BIOS update), such as the one(s) in response to plundervolt https://plundervolt.com/ Writing to the plundervolt-related MSR was particularly helpful to undervolt a thermal-throttled laptop. So! Can either downgrade the BIOS and/or rollback the microcode that your distro is loading during boot.