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,URIBL_BLOCKED,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 A38B6C43387 for ; Tue, 18 Dec 2018 13:19:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7309221852 for ; Tue, 18 Dec 2018 13:19:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726710AbeLRNTG (ORCPT ); Tue, 18 Dec 2018 08:19:06 -0500 Received: from mga12.intel.com ([192.55.52.136]:11938 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726546AbeLRNTG (ORCPT ); Tue, 18 Dec 2018 08:19:06 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Dec 2018 05:19:05 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,368,1539673200"; d="scan'208";a="130937362" Received: from quwen-mobl.ccr.corp.intel.com (HELO localhost) ([10.249.254.215]) by fmsmga001.fm.intel.com with ESMTP; 18 Dec 2018 05:18:56 -0800 Date: Tue, 18 Dec 2018 15:18:53 +0200 From: Jarkko Sakkinen To: Andy Lutomirski Cc: Sean Christopherson , Dave Hansen , X86 ML , Platform Driver , linux-sgx@vger.kernel.org, nhorman@redhat.com, npmccallum@redhat.com, "Ayoun, Serge" , shay.katz-zamir@intel.com, Haitao Huang , Andy Shevchenko , Thomas Gleixner , "Svahn, Kai" , mark.shanahan@intel.com, Suresh Siddha , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Darren Hart , Andy Shevchenko , "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" Subject: Re: [PATCH v17 18/23] platform/x86: Intel SGX driver Message-ID: <20181218131853.GC25667@linux.intel.com> References: <20181116010412.23967-19-jarkko.sakkinen@linux.intel.com> <7d5cde02-4649-546b-0f03-2d6414bb80b5@intel.com> <20181217180102.GA12560@linux.intel.com> <20181217183613.GD12491@linux.intel.com> <20181217184333.GA26920@linux.intel.com> <20181217222047.GG12491@linux.intel.com> <20181218013918.GC333@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-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 17, 2018 at 08:55:02PM -0800, Andy Lutomirski wrote: > On Mon, Dec 17, 2018 at 5:39 PM Jarkko Sakkinen > wrote: > > > > On Mon, Dec 17, 2018 at 02:20:48PM -0800, Sean Christopherson wrote: > > > The only potential hiccup I can see is the build flow. Currently, > > > EADD+EEXTEND is done via a work queue to avoid major performance issues > > > (10x regression) when userspace is building multiple enclaves in parallel > > > using goroutines to wrap Cgo (the issue might apply to any M:N scheduler, > > > but I've only confirmed the Golang case). The issue is that allocating > > > an EPC page acts like a blocking syscall when the EPC is under pressure, > > > i.e. an EPC page isn't immediately available. This causes Go's scheduler > > > to thrash and tank performance[1]. > > > > I don't see any major issues having that kthread. All the code that > > maps the enclave would be removed. > > > > I would only allow to map enclave to process address space after the > > enclave has been initialized i.e. SGX_IOC_ENCLAVE_ATTACH. > > > > What's SGX_IOC_ENCLAVE_ATTACH? Why would it be needed at all? I > would imagine that all pages would be faulted in as needed (or > prefaulted as an optimization) and the enclave would just work in any > process. The way I see it the efficient way to implement this is to have the enclave attached to a single process address space at a time. #PF handler is trivial with multiple address spaces but swapping is a bit tedious as you would need to zap N processes. /Jarkko