Re: [PATCH v33 11/21] x86/sgx: Linux Enclave Driver

[Sean Christopherson]

On Thu, Jun 25, 2020 at 07:23:19PM +0200, Borislav Petkov wrote:
> Also, you had all patches until now split nice and logically doing one
> thing only.
> 
> But this one is huge. Why?
> 
> Why can't you split out the facilities which the driver uses: encl.[ch]
> into a patch, then ioctl.c into a separate one and then the driver into
> a third one? Or do they all belong together inseparably?
> 
> I guess I'll find out eventually but it would've been nice if they were
> split out...

Hmm, I think the most reasonable way to break up this beast would be to
incrementally introduce functionality.  E.g. four or so patches, one for
each ioctl() of ENCLAVE_CREATE, ENCLAVE_ADD_PAGES, ENCLAVE_INIT and
ENCLAVE_SET_ATTRIBUTE, in that order.

Splitting up by file probably wouldn't work very well.  The split is
pretty arbitrary, e.g. encl.[ch] isn't simply a pure representation of an
enclave, there is a lot of the driver details/dependencies in there, i.e.
the functionality between encl/ioctl/driver is all pretty intertwined.

But I think serially introducing each ioctl() would be fairly clean, and
would help readers/reviewers better understand SGX as the patches would
naturally document the process of building an enclave, e.g. CREATE the
enclave, then ADD_PAGES, then INIT the enclave.  SET_ATTRIBUTE is a bit
of an outlier in that it would be chronologically out of order with
respect to building the enclave, but I think that's ok. 

Jarkko, thoughts?