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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 EEFB0C43441 for ; Mon, 19 Nov 2018 16:02:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C2FB520831 for ; Mon, 19 Nov 2018 16:02:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C2FB520831 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-sgx-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729881AbeKTC0N (ORCPT ); Mon, 19 Nov 2018 21:26:13 -0500 Received: from mga04.intel.com ([192.55.52.120]:27569 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729928AbeKTC0N (ORCPT ); Mon, 19 Nov 2018 21:26:13 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Nov 2018 08:02:12 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,253,1539673200"; d="scan'208";a="101478507" Received: from tmuluk-mobl4.ger.corp.intel.com (HELO localhost) ([10.249.254.135]) by orsmga003.jf.intel.com with ESMTP; 19 Nov 2018 08:02:05 -0800 Date: Mon, 19 Nov 2018 18:02:04 +0200 From: Jarkko Sakkinen To: Andy Lutomirski Cc: Dave Hansen , "Christopherson, Sean J" , Jethro Beekman , Florian Weimer , Linux API , Jann Horn , Linus Torvalds , X86 ML , linux-arch , LKML , Peter Zijlstra , Rich Felker , nhorman@redhat.com, npmccallum@redhat.com, "Ayoun, Serge" , shay.katz-zamir@intel.com, linux-sgx@vger.kernel.org, Andy Shevchenko , Thomas Gleixner , Ingo Molnar , Borislav Petkov Subject: Re: RFC: userspace exception fixups Message-ID: <20181119160204.GD13298@linux.intel.com> References: <20181118071548.GA4795@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-sgx-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org On Mon, Nov 19, 2018 at 07:29:36AM -0800, Andy Lutomirski wrote: > 1. The kernel needs some way to know *when* to apply this fixup. > Decoding the instruction stream and doing it to all exceptions that > hit an ENCLU instruction seems like a poor design. I'm not sure why you would ever need to do any type of fixup as the idea is to just return to AEP i.e. from chosen exceptions (EPCM, #UD) the AEP would work the same way as for exceptions that the kernel can deal with except filling the exception information to registers. > 2. It starts exposing what looks like a more generic exception > handling mechanism to userspace, except that it's nonsensical for > anything other than ENCLU. Well, I see the user space and namely the run-time the host for the enclave i.e. middle-man to provide services for emulating instructions etc. /Jarkko