Piracy: ꜱᴀɪʟ ᴛʜᴇ ʜɪɢʜ ꜱᴇᴀꜱ

yeah, more on that: linux kernel has support for cpuid faulting for supported intel cpus since 2017, while amd since only last year. Not sure why amd was slower on this.

No, 5800x3d is zen3 sadly.

But you can actually test it with a small python script:

# docs: https://man.archlinux.org/man/arch_prctl.2
import ctypes
import errno
import mmap
import os
import signal
import subprocess
import sys

SYS_arch_prctl = 158
ARCH_SET_CPUID = 0x1012

libc = ctypes.CDLL(None, use_errno=True)
libc.syscall.restype = ctypes.c_long

def arch_set_cpuid(enabled: bool) -> None:
    rc = libc.syscall(SYS_arch_prctl, ARCH_SET_CPUID, 1 if enabled else 0)
    if rc != 0:
        e = ctypes.get_errno()
        raise OSError(e, os.strerror(e))

def make_cpuid_stub():
    # push rbx
    # xor eax, eax
    # cpuid
    # pop rbx
    # ret
    code = b"\x53\x31\xc0\x0f\xa2\x5b\xc3"
    mm = mmap.mmap(
        -1,
        len(code),
        flags=mmap.MAP_PRIVATE | mmap.MAP_ANONYMOUS,
        prot=mmap.PROT_READ | mmap.PROT_WRITE | mmap.PROT_EXEC,
    )
    mm.write(code)
    addr = ctypes.addressof(ctypes.c_char.from_buffer(mm))
    func = ctypes.CFUNCTYPE(None)(addr)
    func._mm = mm
    return func

def child():
    cpuid = make_cpuid_stub()

    print("Trying normal CPUID...")
    cpuid()
    print("Normal CPUID worked.")

    try:
        arch_set_cpuid(False)
    except OSError as e:
        if e.errno == errno.ENODEV:
            print("CPU does not support CPUID faulting.")
            return 2
        raise

    print("CPUID disabled for this thread. Calling CPUID again...")
    cpuid()  # should SIGSEGV -11 if faulting is supported
    print("Unexpected: CPUID did not fault.")
    return 0

if __name__ == "__main__":
    if len(sys.argv) > 1 and sys.argv[1] == "child":
        raise SystemExit(child())

    p = subprocess.run([sys.executable, __file__, "child"], text=True)
    print(f"child exit code: {p.returncode}")

    if p.returncode == -signal.SIGSEGV:
        print("Result: CPUID faulting is supported and worked.")
    elif p.returncode == 2:
        print("Result: CPUID faulting is not supported by the hardware.")
    else:
        print("Result: test did not complete cleanly.")