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_PASS autolearn=ham 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 D9562C43382 for ; Wed, 26 Sep 2018 20:55:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 90121206B8 for ; Wed, 26 Sep 2018 20:55:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 90121206B8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727266AbeI0DJz (ORCPT ); Wed, 26 Sep 2018 23:09:55 -0400 Received: from mga01.intel.com ([192.55.52.88]:14684 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726727AbeI0DJz (ORCPT ); Wed, 26 Sep 2018 23:09:55 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 26 Sep 2018 13:55:08 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,307,1534834800"; d="scan'208";a="73944779" Received: from kushalre-mobl.amr.corp.intel.com (HELO [10.251.20.48]) ([10.251.20.48]) by fmsmga008.fm.intel.com with ESMTP; 26 Sep 2018 13:49:36 -0700 Subject: Re: [PATCH v14 09/19] x86/mm: x86/sgx: Signal SEGV_SGXERR for #PFs w/ PF_SGX To: Sean Christopherson References: <20180925130845.9962-1-jarkko.sakkinen@linux.intel.com> <20180925130845.9962-10-jarkko.sakkinen@linux.intel.com> <20180926173516.GA10920@linux.intel.com> <2D60780F-ADB4-48A4-AB74-15683493D369@amacapital.net> <9835e288-ba98-2f9e-ac73-504db9512bb9@intel.com> <20180926204400.GA11446@linux.intel.com> Cc: Andy Lutomirski , Andy Lutomirski , Jarkko Sakkinen , X86 ML , Platform Driver , nhorman@redhat.com, npmccallum@redhat.com, "Ayoun, Serge" , shay.katz-zamir@intel.com, linux-sgx@vger.kernel.org, Andy Shevchenko , Dave Hansen , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , LKML From: Dave Hansen Openpgp: preference=signencrypt 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: Wed, 26 Sep 2018 13:49:35 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180926204400.GA11446@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/26/2018 01:44 PM, Sean Christopherson wrote: > On Wed, Sep 26, 2018 at 01:16:59PM -0700, Dave Hansen wrote: >> We also need to clarify how this can happen. Is it through something >> than an app does, or is it solely when the hardware does something under >> the covers, like suspend/resume. > > Are you looking for something in the changelog, the comment, or just > a response? If it's the latter... Comments, please. > On bare metal with a bug-free kernel, the only scenario I'm aware of > where we'll encounter these faults is when hardware pulls the rug out > from under us. In a virtualized environment all bets are off because > the architecture allows VMMs to silently "destroy" the EPC at will, > e.g. KVM, and I believe Hyper-V, will take advantage of this behavior > to support live migration. Post migration, the destination system > will generate PF_SGX because the EPC{M} can't be migrated between > system, i.e. the destination EPCM sees all EPC pages as invalid. OK, cool. That's good background fodder for the changelog. But, for the comment, I'm happy with something like this: /* * The fault resulted from violation of SGX-specific access- * controls. This is expected to be the result of some lower * layer action (CPU suspend/resume, VM migration) and is * not related to anything the OS did. Treat it as an access * error to ensure it is passed up to the app via a signal where * it can be handled. */ I really don't think we need to delve too deeply into the relationship between EPCM and PTEs or anything. Let's just say, "it's not the kernel's fault, it's not the app's fault, so throw up our hands". From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [PATCH v14 09/19] x86/mm: x86/sgx: Signal SEGV_SGXERR for #PFs w/ PF_SGX To: Sean Christopherson References: <20180925130845.9962-1-jarkko.sakkinen@linux.intel.com> <20180925130845.9962-10-jarkko.sakkinen@linux.intel.com> <20180926173516.GA10920@linux.intel.com> <2D60780F-ADB4-48A4-AB74-15683493D369@amacapital.net> <9835e288-ba98-2f9e-ac73-504db9512bb9@intel.com> <20180926204400.GA11446@linux.intel.com> CC: Andy Lutomirski , Andy Lutomirski , Jarkko Sakkinen , X86 ML , Platform Driver , , , "Ayoun, Serge" , , , Andy Shevchenko , Dave Hansen , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , LKML From: Dave Hansen Message-ID: Date: Wed, 26 Sep 2018 13:49:35 -0700 In-Reply-To: <20180926204400.GA11446@linux.intel.com> Content-Type: text/plain; charset="utf-8" Return-Path: dave.hansen@intel.com MIME-Version: 1.0 List-ID: On 09/26/2018 01:44 PM, Sean Christopherson wrote: > On Wed, Sep 26, 2018 at 01:16:59PM -0700, Dave Hansen wrote: >> We also need to clarify how this can happen. Is it through something >> than an app does, or is it solely when the hardware does something under >> the covers, like suspend/resume. > > Are you looking for something in the changelog, the comment, or just > a response? If it's the latter... Comments, please. > On bare metal with a bug-free kernel, the only scenario I'm aware of > where we'll encounter these faults is when hardware pulls the rug out > from under us. In a virtualized environment all bets are off because > the architecture allows VMMs to silently "destroy" the EPC at will, > e.g. KVM, and I believe Hyper-V, will take advantage of this behavior > to support live migration. Post migration, the destination system > will generate PF_SGX because the EPC{M} can't be migrated between > system, i.e. the destination EPCM sees all EPC pages as invalid. OK, cool. That's good background fodder for the changelog. But, for the comment, I'm happy with something like this: /* * The fault resulted from violation of SGX-specific access- * controls. This is expected to be the result of some lower * layer action (CPU suspend/resume, VM migration) and is * not related to anything the OS did. Treat it as an access * error to ensure it is passed up to the app via a signal where * it can be handled. */ I really don't think we need to delve too deeply into the relationship between EPCM and PTEs or anything. Let's just say, "it's not the kernel's fault, it's not the app's fault, so throw up our hands".