I've never understood why Intel didn't just soft-disable AVX512 on P-cores until the OS writes a value to some MSR that means "I understand that only some cores have AVX512".
From the OS side, the change to support it is pretty simple. On the first #UD trap caused by an AVX512 instruction being missing, pin the process to just the P-cores and end the process's timeslice.
From the OS side, the change to support it is pretty simple. On the first #UD trap caused by an AVX512 instruction being missing, pin the process to just the P-cores and end the process's timeslice.