Add cpu policy helper and test

[TSnake41]

Add a CPU policy tooling to be able to check for certain CPU feature.
The test_cpu_policy also logs hosts CPU policies for debugging purposes (especially around live migrations).

Required by #393

[glehmann]

The test doesn't seem actually to validate anything. Am I missing something?

[TSnake41]

The test doesn't seem actually to validate anything. Am I missing something?

There's nothing to validate aside that it doesn't errors.

[glehmann]

Suggested change

	def __init__(self, cpuid: dict[(int, int), int], msr: dict[int, int]):
	def __init__(self, cpuid: dict[tuple[int, int], tuple[int, int, int, int]], msr: dict[int, int]):

[dinhngtu]

@glehmann, is the current recommendation to use native types for typing or the ones from the typing module?

[glehmann]

tuple[int, int, int, int] might be better represented with

@dataclass(frozen=True)
class CpuidRegisters:
    eax: int
    ebx: int
    ecx: int
    edx: int

and used as

def __init__(self, cpuid: dict[tuple[int, int], CpuidRegisters], msr: dict[int, int]):

                current_policy.cpuid[key] = CpuidRegisters(
                    int(eax, 16),
                    int(ebx, 16),
                    int(ecx, 16),
                    int(edx, 16)
                )

Each element can then be accessed by name:

current_policy.cpuid[key].eax

[glehmann]

@glehmann, is the current recommendation to use native types for typing or the ones from the typing module?

No, we had diverging opinions on that last time we discussed it.
I'm proposing to go with builtin types in #460

[dinhngtu]

Please fix the checkers first.

[stormi]

@TSnake41 After a force push, if your PR is ready for re-review, always ask the reviewers who commented for a re-review.