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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 48C59C10DCE for ; Wed, 18 Mar 2020 20:08:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 26FEF2071C for ; Wed, 18 Mar 2020 20:08:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726855AbgCRUIO (ORCPT ); Wed, 18 Mar 2020 16:08:14 -0400 Received: from mga09.intel.com ([134.134.136.24]:15285 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726647AbgCRUIO (ORCPT ); Wed, 18 Mar 2020 16:08:14 -0400 IronPort-SDR: PVG4KAEGAcz4ahobchiutwlSJbDh27bFbzj/023hMXJ/e6lYVMlP3rEa74r3zfMvTtO53HvlhN a2s7r74sAgQw== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Mar 2020 13:08:14 -0700 IronPort-SDR: twV8agTf5YUhg21rmfj5s1NaDr8GiBEeQeOO3J5uApRFFAddd9u3xDJurkLY5IVv7ovyKLC/8x tHaipES1+5PA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,568,1574150400"; d="scan'208";a="268477412" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.202]) by fmsmga004.fm.intel.com with ESMTP; 18 Mar 2020 13:07:48 -0700 Date: Wed, 18 Mar 2020 13:07:48 -0700 From: Sean Christopherson To: Jarkko Sakkinen Cc: linux-sgx@vger.kernel.org Subject: Re: [PATCH] x86/sgx: Fix deadlock and race conditions between fork() and EPC reclaim Message-ID: <20200318200748.GA26164@linux.intel.com> References: <20200317051539.10447-1-sean.j.christopherson@intel.com> <20200318153903.GA37333@linux.intel.com> <20200318155043.GA37726@linux.intel.com> <20200318160316.GE24357@linux.intel.com> <20200318194002.GA48177@linux.intel.com> <20200318194132.GB48177@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200318194132.GB48177@linux.intel.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 Wed, Mar 18, 2020 at 09:41:32PM +0200, Jarkko Sakkinen wrote: > On Wed, Mar 18, 2020 at 09:40:06PM +0200, Jarkko Sakkinen wrote: > > On Wed, Mar 18, 2020 at 09:03:16AM -0700, Sean Christopherson wrote: > > > How on earth is someone doing to dredge up the above information without a > > > comment? Anyone looking at this code without a priori knowledge of the > > > development history will assume the missing synchronize_srcu() is a bug. > > > > By reading the source code of the driver obviously. > > Secondly, there is no development history. It is in epoch state. That's exactly my point. Unless someone knows to look through the pre-historic threads in the intel_sgx mailing list they'll be clueless as to why synchronizing the srcu when attaching a new mm to an enclave is a bad idea. And give it a few years and we'll probably be asking ourselves why there's no synchronize_sruc()... The locking rules between SGX and the core MMU are complex enough as it is, I don't understand why we'd want to make our lives even more difficult.