According to this source (Level 3 - 5) specific CPU rings can not do certain things, such as ring 1, 2, 3 code can not set up GDT, as os kernel would crash.
While it is obvious that Ring 0 can execute all instructions, I am wondering which instructions can not be issued in rings 1, 2 and 3?
I could not find anything on either wikipedia or osdev and similar sources which would state what instructions can not be issued in specific ring.
The following instructions cannot be executed in Ring 3:
LGDT
LLDT
LTR
LIDT
MOV (to and from control registers only)
MOV (to and from debug registers only)
LMSW
CLTS
INVD
WBINVD
INVLPG
HLT
RDMSR
WRMSR
RDPMC
RDTSC
来源：https://stackoverflow.com/questions/39077266/which-instructions-can-not-be-issued-in-specific-cpu-ring