Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu, 28 May 2020 19:16:35 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org,
        linux-sgx@vger.kernel.org, akpm@linux-foundation.org,
        dave.hansen@intel.com, nhorman@redhat.com, npmccallum@redhat.com,
        haitao.huang@intel.com, andriy.shevchenko@linux.intel.com,
        tglx@linutronix.de, kai.svahn@intel.com, josh@joshtriplett.org,
        luto@kernel.org, kai.huang@intel.com, rientjes@google.com,
        cedric.xing@intel.com, puiterwijk@redhat.com,
        Jethro Beekman <jethro@fortanix.com>
Subject: Re: [PATCH v30 08/20] x86/sgx: Add functions to allocate and free
 EPC pages
Message-ID: <20200528171635.GB382@zn.tnic>
References: <20200515004410.723949-1-jarkko.sakkinen@linux.intel.com>
 <20200515004410.723949-9-jarkko.sakkinen@linux.intel.com>
 <20200526125207.GE28228@zn.tnic>
 <20200527042111.GI31696@linux.intel.com>
 <20200527204638.GG1721@zn.tnic>
 <20200528012319.GA7577@linux.intel.com>
 <20200528013617.GD25962@linux.intel.com>
 <20200528065223.GB188849@linux.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20200528065223.GB188849@linux.intel.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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()

>  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

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.

> I'm not sure I follow fully Sean's reasoning but the way alloc is used
> mostly in Linux is to ask through some API the used kernel memory
> allocator to give memory for some kernel data structures.
>
> Agreed that it is not the best match on what we are doing.

Yes, ok, let's stay with "alloc". Agreed.

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

And let's simply forget the "try" - all the functions that can fail and
return an error code, they all try. :-)

> So sgx_alloc_epc_section() is most likely going to be read as "SGX,
> allocate an EPC section".

Or, allocate *from* the EPC section if it returns a pointer to a page
and the comment above it says so...

So to sum up:

* sgx_{alloc,setup}_epc_section - sets up the EPC section and the pages
which belong to it.

* sgx_alloc_page - allocates an EPC page

* sgx_alloc_epc_page_section - allocates a page from any EPC section

I think that makes it pretty clear what each function does...

> I'm thinking that you are over-engineering something this :-) Naming is
> never perfect.

I know, but naming stuff right will pay off later.

Thx.

-- 
Regards/Gruss,
    Boris.

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