Small discovery script

ext.py

import struct
import os
import sys

GREEN = "\033[32m"
RED = "\033[31m"
RESET = "\033[0m"

def _use_color() -> bool:
    if os.environ.get("NO_COLOR") is not None:
        return False
    return sys.stdout.isatty()

USE_COLOR = _use_color()

def color_bool(flag: bool) -> str:
    text = "True" if flag else "False"
    if not USE_COLOR:
        return text
    return f"{GREEN if flag else RED}{text}{RESET}"

def print_table(rows):
    if not rows:
        return
    width = max(len(label) for label, _ in rows)
    for (idx,(label, val)) in enumerate(rows):
        if idx !=0 and idx % 2 == 0:
            print("")
        print(f"{label.ljust(width)}  {color_bool(val)}")

def read_msr(cpu: int, msr: int) -> int:
    """
    Read a 64-bit MSR value from /dev/cpu/<cpu>/msr.
    
    cpu: logical CPU number
    msr: MSR index (integer, e.g. 0x10 for IA32_TSC)
    returns: 64-bit unsigned integer
    """
    path = f"/dev/cpu/{cpu}/msr"
    with open(path, "rb") as f:
        # Seek to offset = msr index
        f.seek(msr)
        data = f.read(8)
        if len(data) != 8:
            raise OSError("Short read from MSR device")
        return struct.unpack("<Q", data)[0]  # little-endian unsigned long long


# Example: read IA32_TSC (0x10) on CPU 0
if __name__ == "__main__":
    # A.3.3 in Intel Manual 
    SECONDARY_VM_EXECUTION_CONTROLS = 0x48b
    # A.3.1 in Intel Manual
    PIN_BASED_VM_EXECUTION_CONTROLS = 0x481

    secondary = read_msr(0, SECONDARY_VM_EXECUTION_CONTROLS)
    pin = read_msr(0, PIN_BASED_VM_EXECUTION_CONTROLS)
    print("Raw value for secondary is", hex(secondary))
    print("Raw value value pin is", hex(pin))

    rows = [
        ("APIC-register virtualization may be enabled?", bool(secondary & (1 << (8 + 32)))),
        ("APIC-register virtualization must be enabled?", (secondary & (1 << 8)) == 1),
        ("Virtual-interrupt delivery may be enabled?", bool(secondary & (1 << (9 + 32)))),
        ("Virtual-interrupt delivery must be enabled?", (secondary & (1 << 8)) == 1),
        ("Process posted interrupts may be enabled?", bool(pin & (1 << (7 + 32)))),
        ("Process posted interrupts must be enabled?", (pin & (1 << 7)) == 1),
    ]

    print_table(rows)