Re: [PATCH 02/25] x86/cpufeatures: Add SGX1 and SGX2 sub-features

[Borislav Petkov]

On Mon, Mar 01, 2021 at 11:40:02PM +1300, Kai Huang wrote:
> SGX2 means "Enclave Dynamic Memory Management", which supports dynamically
> adding/removing EPC pages, plus changing page permission, after enclave is
> initialized. So it allows enclave author to write enclave in more flexible way, and
> also utilize EPC resource more efficiently.

So how is the enclave author going to use "sgx2" in /proc/cpuinfo? Query
it to know whether it can start adding/removing EPC pages or is this
going to be used by scripts?

> Yes I can add "why" into commit message, but isn't the comment after X86_FEATURE_SGX2
> enough? I think people who are interested in SGX will know what SGX2 is and why SGX2
> is useful.

The point is, the commit message should say how this flag in
/proc/cpuinfo is going to be used - not what people interested in sgx
might and might not know.

/proc/cpuinfo is user-visible ABI - you can't add stuff to it just because.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette