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=-2.3 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 A02F8C31E40 for ; Tue, 13 Aug 2019 01:22:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6FF3820665 for ; Tue, 13 Aug 2019 01:22:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726236AbfHMBW2 (ORCPT ); Mon, 12 Aug 2019 21:22:28 -0400 Received: from mga09.intel.com ([134.134.136.24]:15056 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726200AbfHMBW2 (ORCPT ); Mon, 12 Aug 2019 21:22:28 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Aug 2019 18:22:27 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,379,1559545200"; d="scan'208";a="375438220" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.41]) by fmsmga005.fm.intel.com with ESMTP; 12 Aug 2019 18:22:27 -0700 Date: Mon, 12 Aug 2019 18:22:27 -0700 From: Sean Christopherson To: Jarkko Sakkinen Cc: linux-sgx@vger.kernel.org Subject: Re: [PATCH] x86/sgx: Return 0 when !CONFIG_INTEL_SGX_DRIVER Message-ID: <20190813012227.GJ4996@linux.intel.com> References: <20190714143212.971-1-jarkko.sakkinen@linux.intel.com> <20190715135902.GA442@linux.intel.com> <20190801162219.fqmkxlp4mgm4gi3f@linux.intel.com> <20190801162931.GB6783@linux.intel.com> <20190802193321.llx4dcqhslh46toy@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190802193321.llx4dcqhslh46toy@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 Fri, Aug 02, 2019 at 10:33:38PM +0300, Jarkko Sakkinen wrote: > On Thu, Aug 01, 2019 at 09:29:31AM -0700, Sean Christopherson wrote: > > On Thu, Aug 01, 2019 at 07:22:19PM +0300, Jarkko Sakkinen wrote: > > > On Mon, Jul 15, 2019 at 06:59:03AM -0700, Sean Christopherson wrote: > > > > On Sun, Jul 14, 2019 at 05:32:12PM +0300, Jarkko Sakkinen wrote: > > > > > When the config option is not enabled the initialization is always > > > > > succesful. > > > > > > > > Why would the be initialization be considered successful? It's dead code > > > > and memory consumption if the driver can't load. When KVM support gets > > > > added, the initialization can be considered successful if the driver *or* > > > > virtual EPC are enabled and load cleanly. > > > > > > When a config option disabled means it that the functionality does not > > > exist at all, which means that there is nothing to fail. That is why it > > > would be actually better to flag the whole call than the way it is done > > > in this patch. > > > > Regardless of how it's done, the core SGX management shouldn't consume > > resources if it doesn't have downstream consumers. Making INTEL_SGX > > depend on INTEL_SGX_DRIVER is the obvious alternative. > > Is there a specific blocker that prevents using SGX just with KVM when > the latter option is disabled? Nope, KVM does not have any dependencies on the native driver. But if sgx_drv_init() returns 0 when CONFIG_INTEL_SGX_DRIVER=n, then sgx_init() won't handle KVM failure correctly since it will think the native driver initialized cleanly. E.g. with both KVM and driver in play, I was thinking of something like this in sgx_init(): /* Success if the native *or* virtual driver initialized cleanly. */ ret = sgx_drv_init(); ret = sgx_virt_epc_init() ? ret : 0; if (ret) goto err; return 0; If sgx_drv_init() returns 0 when CONFIG_INTEL_SGX_DRIVER=n, then failure in sgx_virt_epc_init() is ignored and we end up with the SGX subsystem wasting resources again.