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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 042ACC433E6 for ; Thu, 4 Feb 2021 03:21:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B495364F43 for ; Thu, 4 Feb 2021 03:21:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234476AbhBDDVM (ORCPT ); Wed, 3 Feb 2021 22:21:12 -0500 Received: from mga12.intel.com ([192.55.52.136]:61543 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233918AbhBDDVL (ORCPT ); Wed, 3 Feb 2021 22:21:11 -0500 IronPort-SDR: FsXH32dWhrF8Qdkpo7O8X+icRkfeTCJ+Wl5oSBunV8JXvBstJBBHhNB+K6wjMBOffl03UYQIK0 u+MDLRl6hZxw== X-IronPort-AV: E=McAfee;i="6000,8403,9884"; a="160328580" X-IronPort-AV: E=Sophos;i="5.79,400,1602572400"; d="scan'208";a="160328580" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Feb 2021 19:20:55 -0800 IronPort-SDR: qK4wTXN4DanvCVJZGOcRFdVJBax3j9hwQbNeg8YTx1O65tL0GHaq/XOSOWsoCH9ipHy9Oa3PNv 6ujPovxrTtKA== X-IronPort-AV: E=Sophos;i="5.79,400,1602572400"; d="scan'208";a="583043391" Received: from hgheewal-mobl2.amr.corp.intel.com ([10.254.80.158]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Feb 2021 19:20:51 -0800 Message-ID: Subject: Re: [RFC PATCH v3 08/27] x86/sgx: Initialize virtual EPC driver even when SGX driver is disabled From: Kai Huang To: Jarkko Sakkinen Cc: Sean Christopherson , linux-sgx@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org, luto@kernel.org, dave.hansen@intel.com, haitao.huang@intel.com, pbonzini@redhat.com, bp@alien8.de, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com Date: Thu, 04 Feb 2021 16:20:49 +1300 In-Reply-To: References: <20210201184040.646ea9923c2119c205b3378d@intel.com> <20210203134906.78b5265502c65f13bacc5e68@intel.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.38.3 (3.38.3-1.fc33) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, 2021-02-04 at 05:09 +0200, Jarkko Sakkinen wrote: > On Thu, Feb 04, 2021 at 05:05:56AM +0200, Jarkko Sakkinen wrote: > > On Thu, Feb 04, 2021 at 03:59:20PM +1300, Kai Huang wrote: > > > On Thu, 2021-02-04 at 03:39 +0200, Jarkko Sakkinen wrote: > > > > On Wed, Feb 03, 2021 at 02:59:47PM -0800, Sean Christopherson wrote: > > > > > On Thu, Feb 04, 2021, Jarkko Sakkinen wrote: > > > > > > On Wed, Feb 03, 2021 at 01:49:06PM +1300, Kai Huang wrote: > > > > > > > What working *incorrectly* thing is related to SGX virtualization? The things > > > > > > > SGX virtualization requires (basically just raw EPC allocation) are all in > > > > > > > sgx/main.c. > > > > > > > > > > > > States: > > > > > > > > > > > > A. SGX driver is unsupported. > > > > > > B. SGX driver is supported and initialized correctly. > > > > > > C. SGX driver is supported and failed to initialize. > > > > > > > > > > > > I just thought that KVM should support SGX when we are either in states A > > > > > > or B. Even the short summary implies this. It is expected that SGX driver > > > > > > initializes correctly if it is supported in the first place. If it doesn't, > > > > > > something is probaly seriously wrong. That is something we don't expect in > > > > > > a legit system behavior. > > > > > > > > > > It's legit behavior, and something we (you?) explicitly want to support. See > > > > > patch 05, x86/cpu/intel: Allow SGX virtualization without Launch Control support. > > > > > > > > What I think would be a sane behavior, would be to allow KVM when > > > > sgx_drv_init() returns -ENODEV (case A). This happens when LC is > > > > not enabled: > > > > > > > > if (!cpu_feature_enabled(X86_FEATURE_SGX_LC)) > > > > return -ENODEV; > > > > > > > > /Jarkko > > > > > > I really don't understand what's the difference between A and C. When "SGX driver is > > > supported and failed to initialize" happens, it just means "SGX driver is > > > unsupported". If it is not the case, can you explicitly point out what will be the > > > problem? > > This is as explicit as I can ever possibly get: > > A: ret == -ENODEV > B: ret == 0 > C: ret != 0 && ret != -ENODEV Let me try again: Why A and C should be treated differently? What will behave incorrectly, in case of C? > > /Jarkko