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=-2.4 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 66209C07E85 for ; Tue, 11 Dec 2018 15:01:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 266AC2084C for ; Tue, 11 Dec 2018 15:01:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 266AC2084C 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-sgx-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726241AbeLKPBx (ORCPT ); Tue, 11 Dec 2018 10:01:53 -0500 Received: from mga06.intel.com ([134.134.136.31]:52613 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726212AbeLKPBx (ORCPT ); Tue, 11 Dec 2018 10:01:53 -0500 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Dec 2018 07:01:52 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,342,1539673200"; d="scan'208";a="100651266" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.154]) by orsmga008.jf.intel.com with ESMTP; 11 Dec 2018 07:01:52 -0800 Date: Tue, 11 Dec 2018 07:01:52 -0800 From: Sean Christopherson To: "Dr. Greg" Cc: Josh Triplett , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, Jarkko Sakkinen , Dave Hansen , Andy Lutomirski , Peter Zijlstra , "H. Peter Anvin" , linux-kernel@vger.kernel.org, linux-sgx@vger.kernel.org, Andy Lutomirski , Haitao Huang , Jethro Beekman Subject: Re: [RFC PATCH v3 0/4] x86: Add exception fixup for SGX ENCLU Message-ID: <20181211150152.GA14731@linux.intel.com> References: <20181210232141.5425-1-sean.j.christopherson@intel.com> <20181210232449.GA11843@localhost> <20181211145339.GA7528@wind.enjellic.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181211145339.GA7528@wind.enjellic.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-sgx-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org On Tue, Dec 11, 2018 at 08:53:39AM -0600, Dr. Greg wrote: > On Mon, Dec 10, 2018 at 03:24:50PM -0800, Josh Triplett wrote: > > Good morning to everyone, I hope the week is progressing well. > > > On Mon, Dec 10, 2018 at 03:21:37PM -0800, Sean Christopherson wrote: > > > At that point I realized it's a hell of a lot easier to simply provide > > > an IOCTL via /dev/sgx that allows userspace to register a per-process > > > ENCLU exception handler. At a high level, the basic idea is the same > > > as the vDSO approach: provide a hardcoded fixup handler for ENCLU and > > > attempt to fixup select unhandled exceptions that occurred in user code. > > > So, on the one hand, this is *absolutely* much cleaner than the VDSO > > approach. On the other hand, this is global process state and has > > some of the same problems as a signal handler as a result. > > Sean's architecture is very simple and straight forward and thus has a > lot going for it. > > As Sean's approach indicates, by linking the exception handler to > current->mm, SGX is very much a per memory map concept. The issue is > that there can be multiple enclaves loaded and excecuting in a > processes memory map, the problem is, execution and thus exception > handling, is very much at the per thread level. Right, but is there a need to have a per-thread code page? The handler isn't per-process any more than the AEP is per-process.