From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8B4DBC433E1 for ; Fri, 29 May 2020 03:38:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 73DFE20721 for ; Fri, 29 May 2020 03:38:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437190AbgE2Dis (ORCPT ); Thu, 28 May 2020 23:38:48 -0400 Received: from mga14.intel.com ([192.55.52.115]:60881 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2436976AbgE2Dir (ORCPT ); Thu, 28 May 2020 23:38:47 -0400 IronPort-SDR: RmS+NA5X7ve+mSJLULcfAxFqcIGKGVqqkYpQglUdjOdfxM9Z5Zkn2u4y98WJtVTCmcA0vBiG4n ryKEu5urIY4Q== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 May 2020 20:38:46 -0700 IronPort-SDR: srrZt4gXFrrJaj61QY8iym0VMpVidDaNCFWzex459ZE0DrikXr4RroEFkjyN5A5GkXGPp3Wzvd QRf9YXr1lZow== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,447,1583222400"; d="scan'208";a="292232848" Received: from pratuszn-mobl.ger.corp.intel.com (HELO localhost) ([10.252.58.65]) by fmsmga004.fm.intel.com with ESMTP; 28 May 2020 20:38:37 -0700 Date: Fri, 29 May 2020 06:38:36 +0300 From: Jarkko Sakkinen To: Sean Christopherson Cc: Borislav Petkov , 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 Subject: Re: [PATCH v30 08/20] x86/sgx: Add functions to allocate and free EPC pages Message-ID: <20200529033836.GD6182@linux.intel.com> References: <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> <20200528171635.GB382@zn.tnic> <20200528190718.GA2147934@linux.intel.com> <20200528195917.GF30353@linux.intel.com> <20200529032816.GC6182@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200529032816.GC6182@linux.intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 29, 2020 at 06:28:28AM +0300, Jarkko Sakkinen wrote: > On Thu, May 28, 2020 at 12:59:17PM -0700, Sean Christopherson wrote: > > On Thu, May 28, 2020 at 10:07:18PM +0300, Jarkko Sakkinen wrote: > > > On Thu, May 28, 2020 at 07:16:35PM +0200, Borislav Petkov wrote: > > > > Lemme reply to all mails with one. :-) > > > > 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. > > > > "allocate an EPC page from the specified section" > > > > It also works if/when we add NUMA awareness, e.g. sgx_alloc_epc_page_node() > > means "allocate an EPC page from the specified node". Note that I'm not > > inventing these from scratch, simply stealing them from alloc_pages() and > > alloc_pages_node(). The section thing is unique to SGX, but the underlying > > concept is the same. > > Then it should be sgx_alloc_epc_page_from_section() if you go with that. > Otherwise it is mixes too much with the section. I did read these mails > first quickly and first thought that functions were doing something with > sgx_epc_section and not with pages. > > Only with a deeper look that it's the name for allocating a page. > > I think both names are waste of screen estate. Too long. > > > > * 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(). > > > > FWIW, I really, really dislike "grab". The nomenclature for normal memory > > and pages uses "alloc" when taking a page off a free list, and "grab" when > > elevating the refcount. I don't understand the motivation for diverging > > from that. SGX is weird enough as is, using names that don't align with > > exist norms will only serve to further obfuscate the code. > > OK, what would be a better name then? The semantics are not standard > memory allocation semantics in the first place. And kdoc in v30 speaks > about grabbing. I can live with sgx_alloc_epc_page() or sgx_alloc_epc_page_from_section() although I'd prefer the shorter form. /Jarkko