Re: [PATCH v30 08/20] x86/sgx: Add functions to allocate and free EPC pages

[Jarkko Sakkinen]

On Wed, May 27, 2020 at 05:52:17PM -0700, Sean Christopherson wrote:
> On Wed, May 27, 2020 at 10:46:38PM +0200, Borislav Petkov wrote:
> > On Tue, May 26, 2020 at 09:21:11PM -0700, Sean Christopherson wrote:
> > > In other words, sgx_alloc_epc_section() is poorly named.  It doesn't
> > > actually allocate EPC, it allocates kernel structures to map and track EPC.
> > > sgx_(un)map_epc_section() would be more accurate and would hopefully
> > > alleviate some of the confusion.
> > 
> > Makes sense.
> > 
> > > I have no objection to renaming __sgx_alloc_try_alloc_page() to something
> > > like sgx_alloc_epc_page_section or whatever, but IMO using get/put will be
> > > horrendously confusing.
> > 
> > Ok. My only issue is that the naming nomenclature sounds strange and
> > confusing as it is. "try" in an "alloc" function is kinda tautological -
> > of course the function will try to do its best. :)
> 
> Heh, so what you're saying is we should add __sgx_really_try_alloc_page()?
> 
> > And there are three functions having "alloc" in the name so I can
> > imagine someone getting very confused when having to stare at that code.
> > 
> > So at least naming them in a way so that it is clear what kind of pages
> > they "allocate" - i.e., what they actually do - would be a step in the
> > right direction...
> 
> Ya, and things will only get more confusing when actual NUMA awareness gets
> thrown into the mix.
> 
> Jarkko, splicing in the NUMA awareness code, what do you think about:
> 
>   sgx_alloc_epc_section -> sgx_map_epc_section
>   sgx_free_epc_section  -> sgx_unmap_epc_section

Here alloc makes sense because memory gets allocated for the data
structures.

>   sgx_alloc_page        -> sgx_alloc_epc_page
>   sgx_free_page         -> sgx_free_epc_page
> 
>   sgx_try_alloc_page    -> sgx_alloc_epc_page_node
>   __sgx_try_alloc_page  -> sgx_alloc_epc_page_section

I'm going with sgx_grab_page() and sgx_try_grab_page().

/Jarkko