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=-6.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 01BD9C433E9 for ; Thu, 4 Feb 2021 03:09:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8340464F4D for ; Thu, 4 Feb 2021 03:09:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233533AbhBDDJt (ORCPT ); Wed, 3 Feb 2021 22:09:49 -0500 Received: from mail.kernel.org ([198.145.29.99]:55348 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231759AbhBDDJr (ORCPT ); Wed, 3 Feb 2021 22:09:47 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9336D64E42; Thu, 4 Feb 2021 03:09:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1612408147; bh=DO17Ji2Z5OwqwjGdem1y7DJtxEZJ3ylboTT2HlBtRhs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=iwR0WxeTygLTUEKdAq8piwO5YNHkpC9sf7RbD4GmDQnYSEAkMVCYG0rdzdBxoo7JU 47N7wUNkNlwe2H3iNJ/SY4x83z/G+HNXpQTaLE7G4om3cyFu6R5MZsOhayZO19dq60 tCjO3m092zxY6i2NVBeYnphs9wLvp2RJppI/uy24poCWh4Kk3DjHaOZrht9uEDZiHY N6QPitm+2WSN3/2yop23uYQjqLeh2cGFbYVXGddIfg1WvSQbZWyW9YypitoxXmMAJJ YlqJ7/ZjS6d6467KmKU1GjRmb//UrGLBwqgvxmVIgbpeWlnzEhZVJdxu0X0dAh9uQB mknuElEilXhig== Date: Thu, 4 Feb 2021 05:09:00 +0200 From: Jarkko Sakkinen To: Kai Huang 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 Subject: Re: [RFC PATCH v3 08/27] x86/sgx: Initialize virtual EPC driver even when SGX driver is disabled Message-ID: References: <20210201184040.646ea9923c2119c205b3378d@intel.com> <20210203134906.78b5265502c65f13bacc5e68@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org 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 /Jarkko