Re: [PATCH v11 18/20] x86: Handle TDX erratum to reset TDX private memory during kexec() and reboot

[Dave Hansen]

On 6/13/23 16:18, Huang, Kai wrote:
> On Tue, 2023-06-13 at 07:25 -0700, Hansen, Dave wrote:
>> On 6/12/23 17:51, Huang, Kai wrote:
>>> If we introduce a helper to mark a page as TDX private page,
>> Let me get this right: you have working, functional code for a
>> highly-unlikely scenario (kernel bugs or even more rare hardware
>> errors).  But, you want to optimize this super-rare case?  It's not fast
>> enough?
>>
>> Is there any other motivation here that I'm missing?
>>
> No it's not about speed.  The motivation is to have a common code to yield less
> line of code, though I don't have clear number of how many LoC can be reduced.

OK, so ... ballpark.  How many lines of code are we going to _save_ for
this super-rare case?  10?  100?  1000?

The upside is saving X lines of code ... somewhere.  The downside is
adding Y lines of code ... somewhere else and maybe breaking things in
the process.

You've evidently done _some_ kind of calculus in your head to make this
tradeoff worthwhile.  I'd love to hear what your calculus is, even if
it's just a gut feel.

Could you share your logic here, please?