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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 CDE15C433DB for ; Mon, 15 Mar 2021 19:48:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 91FB964F4A for ; Mon, 15 Mar 2021 19:48:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233736AbhCOTsK (ORCPT ); Mon, 15 Mar 2021 15:48:10 -0400 Received: from mga04.intel.com ([192.55.52.120]:31609 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233731AbhCOTri (ORCPT ); Mon, 15 Mar 2021 15:47:38 -0400 IronPort-SDR: ZQFecpGVbVVCb4XBmuhJ5S3ZOYFFPKzlsHPpxjb4X5h5a2gmXkLi0JG23yOVO9DAn0Y4lP0v5F yAuVcQjJz0SQ== X-IronPort-AV: E=McAfee;i="6000,8403,9924"; a="186768415" X-IronPort-AV: E=Sophos;i="5.81,251,1610438400"; d="scan'208";a="186768415" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Mar 2021 12:47:31 -0700 IronPort-SDR: wpVcFtBb+Zbfp1TzY+fc+O4JY0vVlDOvnAMyn3xcSQWm+6NyN2EFtN6GmAhxsjyeEMNvRMlbNw LTvi8SLdsbHw== X-IronPort-AV: E=Sophos;i="5.81,251,1610438400"; d="scan'208";a="601550909" Received: from lguadamu-mobl1.amr.corp.intel.com (HELO [10.213.176.188]) ([10.213.176.188]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Mar 2021 12:47:30 -0700 Subject: Re: [PATCH v4 2/3] x86/sgx: Replace section local dirty page lists with a global list To: Jarkko Sakkinen Cc: linux-sgx@vger.kernel.org, Dave Hansen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org References: <20210313160119.1318533-1-jarkko@kernel.org> <20210313160119.1318533-3-jarkko@kernel.org> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzShEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gPGRhdmVAc3I3MS5uZXQ+wsF7BBMBAgAlAhsDBgsJCAcDAgYVCAIJ CgsEFgIDAQIeAQIXgAUCTo3k0QIZAQAKCRBoNZUwcMmSsMO2D/421Xg8pimb9mPzM5N7khT0 2MCnaGssU1T59YPE25kYdx2HntwdO0JA27Wn9xx5zYijOe6B21ufrvsyv42auCO85+oFJWfE K2R/IpLle09GDx5tcEmMAHX6KSxpHmGuJmUPibHVbfep2aCh9lKaDqQR07gXXWK5/yU1Dx0r VVFRaHTasp9fZ9AmY4K9/BSA3VkQ8v3OrxNty3OdsrmTTzO91YszpdbjjEFZK53zXy6tUD2d e1i0kBBS6NLAAsqEtneplz88T/v7MpLmpY30N9gQU3QyRC50jJ7LU9RazMjUQY1WohVsR56d ORqFxS8ChhyJs7BI34vQusYHDTp6PnZHUppb9WIzjeWlC7Jc8lSBDlEWodmqQQgp5+6AfhTD kDv1a+W5+ncq+Uo63WHRiCPuyt4di4/0zo28RVcjtzlGBZtmz2EIC3vUfmoZbO/Gn6EKbYAn rzz3iU/JWV8DwQ+sZSGu0HmvYMt6t5SmqWQo/hyHtA7uF5Wxtu1lCgolSQw4t49ZuOyOnQi5 f8R3nE7lpVCSF1TT+h8kMvFPv3VG7KunyjHr3sEptYxQs4VRxqeirSuyBv1TyxT+LdTm6j4a mulOWf+YtFRAgIYyyN5YOepDEBv4LUM8Tz98lZiNMlFyRMNrsLV6Pv6SxhrMxbT6TNVS5D+6 UorTLotDZKp5+M7BTQRUY85qARAAsgMW71BIXRgxjYNCYQ3Xs8k3TfAvQRbHccky50h99TUY sqdULbsb3KhmY29raw1bgmyM0a4DGS1YKN7qazCDsdQlxIJp9t2YYdBKXVRzPCCsfWe1dK/q 66UVhRPP8EGZ4CmFYuPTxqGY+dGRInxCeap/xzbKdvmPm01Iw3YFjAE4PQ4hTMr/H76KoDbD cq62U50oKC83ca/PRRh2QqEqACvIH4BR7jueAZSPEDnzwxvVgzyeuhwqHY05QRK/wsKuhq7s UuYtmN92Fasbxbw2tbVLZfoidklikvZAmotg0dwcFTjSRGEg0Gr3p/xBzJWNavFZZ95Rj7Et db0lCt0HDSY5q4GMR+SrFbH+jzUY/ZqfGdZCBqo0cdPPp58krVgtIGR+ja2Mkva6ah94/oQN lnCOw3udS+Eb/aRcM6detZr7XOngvxsWolBrhwTQFT9D2NH6ryAuvKd6yyAFt3/e7r+HHtkU kOy27D7IpjngqP+b4EumELI/NxPgIqT69PQmo9IZaI/oRaKorYnDaZrMXViqDrFdD37XELwQ gmLoSm2VfbOYY7fap/AhPOgOYOSqg3/Nxcapv71yoBzRRxOc4FxmZ65mn+q3rEM27yRztBW9 AnCKIc66T2i92HqXCw6AgoBJRjBkI3QnEkPgohQkZdAb8o9WGVKpfmZKbYBo4pEAEQEAAcLB XwQYAQIACQUCVGPOagIbDAAKCRBoNZUwcMmSsJeCEACCh7P/aaOLKWQxcnw47p4phIVR6pVL e4IEdR7Jf7ZL00s3vKSNT+nRqdl1ugJx9Ymsp8kXKMk9GSfmZpuMQB9c6io1qZc6nW/3TtvK pNGz7KPPtaDzvKA4S5tfrWPnDr7n15AU5vsIZvgMjU42gkbemkjJwP0B1RkifIK60yQqAAlT YZ14P0dIPdIPIlfEPiAWcg5BtLQU4Wg3cNQdpWrCJ1E3m/RIlXy/2Y3YOVVohfSy+4kvvYU3 lXUdPb04UPw4VWwjcVZPg7cgR7Izion61bGHqVqURgSALt2yvHl7cr68NYoFkzbNsGsye9ft M9ozM23JSgMkRylPSXTeh5JIK9pz2+etco3AfLCKtaRVysjvpysukmWMTrx8QnI5Nn5MOlJj 1Ov4/50JY9pXzgIDVSrgy6LYSMc4vKZ3QfCY7ipLRORyalFDF3j5AGCMRENJjHPD6O7bl3Xo 4DzMID+8eucbXxKiNEbs21IqBZbbKdY1GkcEGTE7AnkA3Y6YB7I/j9mQ3hCgm5muJuhM/2Fr OPsw5tV/LmQ5GXH0JQ/TZXWygyRFyyI2FqNTx4WHqUn3yFj8rwTAU1tluRUYyeLy0ayUlKBH ybj0N71vWO936MqP6haFERzuPAIpxj2ezwu0xb1GjTk4ynna6h5GjnKgdfOWoRtoWndMZxbA z5cecg== Message-ID: Date: Mon, 15 Mar 2021 12:47:29 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/15/21 12:14 PM, Jarkko Sakkinen wrote: > On Mon, Mar 15, 2021 at 09:03:21AM -0700, Dave Hansen wrote: >> On 3/13/21 8:01 AM, Jarkko Sakkinen wrote: >>> Reset initialized EPC pages in sgx_dirty_page_list to uninitialized state, >>> and free them using sgx_free_epc_page(). Do two passes, as for SECS pages >>> the first round can fail, if all child pages have not yet been removed. >>> The driver puts all pages on startup first to sgx_dirty_page_list, as the >>> initialization could be triggered by kexec(), meaning that pages have been >>> reserved for active enclaves before the operation. >>> >>> The section local lists are redundant, as sgx_free_epc_page() figures >>> out the correction by using epc_page->section. >> >> During normal runtime, the "ksgxd" daemon behaves like a version of >> kswapd just for SGX. But, its first job is to initialize enclave >> memory. This is done in a a separate thread because this initialization >> can be quite slow. >> >> Currently, the SGX boot code places each enclave page on a >> sgx_section-local list (init_laundry_list). Once it starts up, the >> ksgxd code walks over that list and populates the actual SGX page allocator. >> >> However, the per-section structures are going away to make way for the >> SGX NUMA allocator. There's also little need to have a per-section >> structure; the enclave pages are all treated identically, and they can >> be placed on the correct allocator list from metadata stoered in the >> enclave page itself. >> > Is this a suggestion how to rephrase the commit message? :-) Yep. >>> static int ksgxd(void *p) >>> { >>> - int i; >>> + struct sgx_epc_page *page; >>> + LIST_HEAD(dirty); >>> + int i, ret; >>> >>> set_freezable(); >>> >>> /* >>> - * Sanitize pages in order to recover from kexec(). The 2nd pass is >>> - * required for SECS pages, whose child pages blocked EREMOVE. >>> + * Reset initialized EPC pages in sgx_dirty_page_list to uninitialized state, >>> + * and free them using sgx_free_epc_page(). >> >> I'm not a fan of comments that tell us verbatim what the code does. > > So, what are you suggesting? Remove the whole comment or parts of it? I'm > presuming that you suggest removing the "top-level" part. Just please make it more relevant and informative. I can tell this is processing 'sgx_dirty_page_list' and calling sgx_free_epc_page() from the code. I don't need a comment to tell me that. A better comment would say: Take enclave pages from the init code, ensure they are clean, and free the back into the main SGX page allocator That tells what *role* this code plays (connecting init code to the allocator) in a way that just verbatim telling what code is called does not.