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

[Jarkko Sakkinen]

On Thu, May 28, 2020 at 07:16:35PM +0200, Borislav Petkov wrote:
> Lemme reply to all mails with one. :-)
> 
> I think Sean almost had it:
> 
> >  sgx_alloc_epc_section -> sgx_map_epc_section
> >  sgx_free_epc_section  -> sgx_unmap_epc_section
> 
> Or even
> 
>   sgx_setup_epc_section()
>   sgx_free_epc_section()

I like these. Lets lock in.

> And except those last two. Those are allocating a page from the EPC
> sections so I'd call them:
> 
> sgx_try_alloc_page    -> sgx_alloc_epc_page_section
> __sgx_try_alloc_page  -> __sgx_alloc_epc_page_section
> 
> former doing the loop, latter doing the per-section list games.

sgx_alloc_epc_page_section() is a bit nasty and long name to use for
grabbing a page. And even the documentation spoke about grabbing before
this naming discussion. I think it is a great description what is going
on.  Everytime I talk about the subject I talk about grabbing.

Lets just say that your suggestion, I could not use in a conference
talk as a verb when I describe what is going on. That function
signature does not fit to my mouth :-) I would talk about
grabbing a page.

This how I refactored yesterday (is in my GIT tree already):

/**
 * sgx_grab_page() - Grab a free EPC page
 * @owner:	the owner of the EPC page
 * @reclaim:	reclaim pages if necessary
 *
 * Iterate through EPC sections and borrow a free EPC page to the caller. When a
 * page is no longer needed it must be released with sgx_free_page(). If
 * @reclaim is set to true, directly reclaim pages when we are out of pages. No
 * mm's can be locked when @reclaim is set to true.
 *
 * Finally, wake up ksgxswapd when the number of pages goes below the watermark
 * before returning back to the caller.
 *
 * Return:
 *   an EPC page,
 *   -errno on error
 */

I also rewrote the kdoc.

I do agree that sgx_try_grab_page() should be renamed as __sgx_grab_page().

/Jarkko