Re: [PATCH v8 27/40] x86/boot: Add Confidential Computing type to setup_data

Brijesh Singh
2021-12-13T15:55:34Z

On 12/13/21 9:08 AM, Dave Hansen wrote:
> On 12/13/21 6:49 AM, Brijesh Singh wrote:
>>> I was more concerned that this structure could change sizes if it were
>>> compiled on 32-bit versus 64-bit code.  For kernel ABIs, we try not to
>>> do that.
>>>
>>> Is this somehow OK when talking to firmware?  Or can a 32-bit OS and
>>> 64-bit firmware never interact?
>>
>> For SNP, both the firmware and OS need to be 64-bit. IIRC, both the
>> Linux and OVMF do not enable the memory encryption for the 32-bit.
>
> Could you please make the structure's size invariant?

Ack. I will make the required changes.

That's great if
> there's no problem in today's implementation, but it's best no to leave
> little land mines like this around. Let's say someone copies your code
> as an example of something that interacts with a firmware table a few
> years or months down the road.
>