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=-8.9 required=3.0 tests=BAYES_00,DATE_IN_PAST_24_48, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 4D0F8C4360C for ; Fri, 5 Mar 2021 17:39:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 29450650BC for ; Fri, 5 Mar 2021 17:39:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230126AbhCERib (ORCPT ); Fri, 5 Mar 2021 12:38:31 -0500 Received: from mga03.intel.com ([134.134.136.65]:60556 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229616AbhCERiL (ORCPT ); Fri, 5 Mar 2021 12:38:11 -0500 IronPort-SDR: wxJbIinaCZWXw/rufTYD1Erd5Wv/kkJVm0mLfzQFX3ny6M4du2vt9FY4A6TRPJNHT2G18rwdfr lfuTNXg+zUVA== X-IronPort-AV: E=McAfee;i="6000,8403,9914"; a="187747005" X-IronPort-AV: E=Sophos;i="5.81,225,1610438400"; d="scan'208";a="187747005" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Mar 2021 09:38:10 -0800 IronPort-SDR: i/1+a3A7ccysz/lIx9zz1SkMSoP5qxWNfjt55EfMrh3UCPngZ16toJm8JHdM4fMa3K/hUHIwYM of7Y3Fwtu94g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,225,1610438400"; d="scan'208";a="375069277" Received: from viggo.jf.intel.com (HELO ray) ([10.54.77.144]) by fmsmga007.fm.intel.com with ESMTP; 05 Mar 2021 09:38:09 -0800 Received: from [127.0.0.1] (localhost [127.0.0.1]) by ray (Postfix) with ESMTP id 21282E2301; Wed, 3 Mar 2021 10:02:27 -0800 (PST) Subject: Re: [PATCH v3 3/5] x86/sgx: Replace section->init_laundry_list with a temp list To: Jarkko Sakkinen , linux-sgx@vger.kernel.org Cc: Dave Hansen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org References: <20210303150323.433207-1-jarkko@kernel.org> <20210303150323.433207-4-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: <5f0c773f-4da1-7418-be42-e11427c2f137@intel.com> Date: Wed, 3 Mar 2021 10:02:27 -0800 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: <20210303150323.433207-4-jarkko@kernel.org> 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 ... > -static void sgx_sanitize_section(struct sgx_epc_section *section) > +static void sgx_sanitize_section(struct list_head *laundry) > { Does this need a better function name now that it's not literally dealing with sections at *all*? sgx_sanitize_pages() perhaps. > struct sgx_epc_page *page; > LIST_HEAD(dirty); > int ret; > > /* init_laundry_list is thread-local, no need for a lock: */ > - while (!list_empty(§ion->init_laundry_list)) { > + while (!list_empty(laundry)) { > if (kthread_should_stop()) > return; > > - /* needed for access to ->page_list: */ > - spin_lock(§ion->lock); > - > - page = list_first_entry(§ion->init_laundry_list, > - struct sgx_epc_page, list); > + page = list_first_entry(laundry, struct sgx_epc_page, list); > > ret = __eremove(sgx_get_epc_virt_addr(page)); > - if (!ret) > - list_move(&page->list, §ion->page_list); > - else > + if (!ret) { > + /* The page is clean - move to the free list. */ > + list_del(&page->list); > + sgx_free_epc_page(page); > + } else { > + /* The page is not yet clean - move to the dirty list. */ > list_move_tail(&page->list, &dirty); > - > - spin_unlock(§ion->lock); > + } > > cond_resched(); > } > > - list_splice(&dirty, §ion->init_laundry_list); > + list_splice(&dirty, laundry); > } > > static bool sgx_reclaimer_age(struct sgx_epc_page *epc_page) > @@ -400,6 +398,7 @@ static bool sgx_should_reclaim(unsigned long watermark) > > static int ksgxd(void *p) > { > + struct list_head *laundry = p; > int i; > > set_freezable(); > @@ -408,16 +407,13 @@ static int ksgxd(void *p) > * Sanitize pages in order to recover from kexec(). The 2nd pass is > * required for SECS pages, whose child pages blocked EREMOVE. > */ > - for (i = 0; i < sgx_nr_epc_sections; i++) > - sgx_sanitize_section(&sgx_epc_sections[i]); > + sgx_sanitize_section(laundry); > + sgx_sanitize_section(laundry); Did you intend to call this twice? > - for (i = 0; i < sgx_nr_epc_sections; i++) { > - sgx_sanitize_section(&sgx_epc_sections[i]); > + if (!list_empty(laundry)) > + WARN(1, "EPC section %d has unsanitized pages.\n", i); > > - /* Should never happen. */ > - if (!list_empty(&sgx_epc_sections[i].init_laundry_list)) > - WARN(1, "EPC section %d has unsanitized pages.\n", i); > - } > + kfree(laundry); This is a bit unfortunate. 'laundry' is allocated up in another thread and the lifetime isn't obvious. It's just 32 bytes, but this is just asking to be leaked. > while (!kthread_should_stop()) { > if (try_to_freeze()) > @@ -436,11 +432,11 @@ static int ksgxd(void *p) > return 0; > } > > -static bool __init sgx_page_reclaimer_init(void) > +static bool __init sgx_page_reclaimer_init(struct list_head *laundry) > { > struct task_struct *tsk; > > - tsk = kthread_run(ksgxd, NULL, "ksgxd"); > + tsk = kthread_run(ksgxd, laundry, "ksgxd"); > if (IS_ERR(tsk)) > return false; > > @@ -614,7 +610,8 @@ void sgx_free_epc_page(struct sgx_epc_page *page) > > static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, > unsigned long index, > - struct sgx_epc_section *section) > + struct sgx_epc_section *section, > + struct list_head *laundry) > { I think this at least need a comment somewhere about what this function is doing with 'laundry'. > unsigned long nr_pages = size >> PAGE_SHIFT; > unsigned long i; > @@ -632,13 +629,12 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, > section->phys_addr = phys_addr; > spin_lock_init(§ion->lock); > INIT_LIST_HEAD(§ion->page_list); > - INIT_LIST_HEAD(§ion->init_laundry_list); > > for (i = 0; i < nr_pages; i++) { > section->pages[i].section = index; > section->pages[i].flags = 0; > section->pages[i].owner = NULL; > - list_add_tail(§ion->pages[i].list, §ion->init_laundry_list); > + list_add_tail(§ion->pages[i].list, laundry); > } > > section->free_cnt = nr_pages; > @@ -656,7 +652,7 @@ static inline u64 __init sgx_calc_section_metric(u64 low, u64 high) > ((high & GENMASK_ULL(19, 0)) << 32); > } > > -static bool __init sgx_page_cache_init(void) > +static bool __init sgx_page_cache_init(struct list_head *laundry) > { > u32 eax, ebx, ecx, edx, type; > u64 pa, size; > @@ -679,7 +675,7 @@ static bool __init sgx_page_cache_init(void) > > pr_info("EPC section 0x%llx-0x%llx\n", pa, pa + size - 1); > > - if (!sgx_setup_epc_section(pa, size, i, &sgx_epc_sections[i])) { > + if (!sgx_setup_epc_section(pa, size, i, &sgx_epc_sections[i], laundry)) { > pr_err("No free memory for an EPC section\n"); > break; > } This is a great place for a comment about what is coming back on 'laundry'. > @@ -697,18 +693,25 @@ static bool __init sgx_page_cache_init(void) > > static int __init sgx_init(void) > { > + struct list_head *laundry; > int ret; > int i; > > if (!cpu_feature_enabled(X86_FEATURE_SGX)) > return -ENODEV; > > - if (!sgx_page_cache_init()) { > + laundry = kzalloc(sizeof(*laundry), GFP_KERNEL); > + if (!laundry) > + return -ENOMEM; > + > + INIT_LIST_HEAD(laundry); > + > + if (!sgx_page_cache_init(laundry)) { > ret = -ENOMEM; > goto err_page_cache; > } > > - if (!sgx_page_reclaimer_init()) { > + if (!sgx_page_reclaimer_init(laundry)) { > ret = -ENOMEM; > goto err_page_cache; > } I really don't like this being dynamically allocated, especially since it's freed in another task in a non-obvious place. Wouldn't this all just be a lot simpler if we had a global list_head? That will eat a whopping 16 bytes of space.