This is what Intel's proposed X86S [0] is designed for.
> X86S is a legacy-reduced-OS ISA that removes outdated execution modes and operating system
ISA.
> The presence of the X86S ISA is enumerated by a single, main CPUID feature
LEGACY_REDUCED_ISA in CPUID 7.1.ECX[2] which implies all the ISA removals described in this document. A new, 64-bit “start-up” interprocessor interrupt (SIPI) has a separate CPUID feature flag.
> X86S is a legacy-reduced-OS ISA that removes outdated execution modes and operating system ISA.
> The presence of the X86S ISA is enumerated by a single, main CPUID feature LEGACY_REDUCED_ISA in CPUID 7.1.ECX[2] which implies all the ISA removals described in this document. A new, 64-bit “start-up” interprocessor interrupt (SIPI) has a separate CPUID feature flag.
[0] https://cdrdv2.intel.com/v1/dl/getContent/776648 [pdf warning]