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=-5.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 A9738C47257 for ; Thu, 7 May 2020 05:02:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 93CA720753 for ; Thu, 7 May 2020 05:02:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726326AbgEGFCy (ORCPT ); Thu, 7 May 2020 01:02:54 -0400 Received: from mga05.intel.com ([192.55.52.43]:59002 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725763AbgEGFCx (ORCPT ); Thu, 7 May 2020 01:02:53 -0400 IronPort-SDR: h8az6S7szrE8Xb62WyJrk2us2rYL+/KGJiblkjevAnjGjQQW31yzhWNu6qLBKFT5xoVbbq/XN5 2K4CaTTB35Gw== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 May 2020 22:02:52 -0700 IronPort-SDR: stdfQH4ZVMo6zVmW4SopcSsgg9s+guoo41EqFH2xpkk9fsSUyXe6bTjGfQ3X9Y60kFGVdXTnzn T+ZnPo2Dxe0g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,362,1583222400"; d="scan'208";a="462020755" Received: from hhuan26-mobl1.amr.corp.intel.com ([10.213.160.47]) by fmsmga006.fm.intel.com with ESMTP; 06 May 2020 22:02:51 -0700 Content-Type: text/plain; charset=iso-8859-15; format=flowed; delsp=yes To: "Nathaniel McCallum" , "Sean Christopherson" Cc: "Jarkko Sakkinen" , linux-kernel@vger.kernel.org, x86@kernel.org, linux-sgx@vger.kernel.org, akpm@linux-foundation.org, dave.hansen@intel.com, "Neil Horman" , "Huang, Haitao" , andriy.shevchenko@linux.intel.com, tglx@linutronix.de, "Svahn, Kai" , bp@alien8.de, "Josh Triplett" , luto@kernel.org, kai.huang@intel.com, "David Rientjes" , "Xing, Cedric" , "Patrick Uiterwijk" Subject: Re: [PATCH v29 00/20] Intel SGX foundations References: <20200421215316.56503-1-jarkko.sakkinen@linux.intel.com> <20200506221422.GK3329@linux.intel.com> Date: Thu, 07 May 2020 00:02:50 -0500 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: "Haitao Huang" Organization: Intel Corp Message-ID: In-Reply-To: <20200506221422.GK3329@linux.intel.com> User-Agent: Opera Mail/1.0 (Win32) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 06 May 2020 17:14:22 -0500, Sean Christopherson wrote: > On Wed, May 06, 2020 at 05:42:42PM -0400, Nathaniel McCallum wrote: >> Tested on Enarx. This requires a patch[0] for v29 support. >> >> Tested-by: Nathaniel McCallum >> >> However, we did uncover a small usability issue. See below. >> >> [0]: >> https://github.com/enarx/enarx/pull/507/commits/80da2352aba46aa7bc6b4d1fccf20fe1bda58662 > > ... > >> > * Disallow mmap(PROT_NONE) from /dev/sgx. Any mapping (e.g. >> anonymous) can >> > be used to reserve the address range. Now /dev/sgx supports only >> opaque >> > mappings to the (initialized) enclave data. >> >> The statement "Any mapping..." isn't actually true. >> >> Enarx creates a large enclave (currently 64GiB). This worked when we >> created a file-backed mapping on /dev/sgx/enclave. However, switching >> to an anonymous mapping fails with ENOMEM. We suspect this is because >> the kernel attempts to allocate all the pages and zero them but there >> is insufficient RAM available. We currently work around this by >> creating a shared mapping on /dev/zero. > > Hmm, the kernel shouldn't actually allocate physical pages unless they're > written. I'll see if I can reproduce. > For larger size mmap, I think it requires enabling vm overcommit mode 1: echo 1 | sudo tee /proc/sys/vm/overcommit_memory >> If we want to keep this mmap() strategy, we probably don't want to >> advise mmap(ANON) if it allocates all the memory for the enclave ahead >> of time, even if it won't be used. This would be wasteful. >> >> OTOH, having to mmap("/dev/zero") seems a bit awkward. -- Using Opera's mail client: http://www.opera.com/mail/