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=-16.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 75BA6C4332D for ; Mon, 15 Mar 2021 13:52:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 069F264EEF for ; Mon, 15 Mar 2021 13:52:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229743AbhCONwA (ORCPT ); Mon, 15 Mar 2021 09:52:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:54874 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229524AbhCONvn (ORCPT ); Mon, 15 Mar 2021 09:51:43 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D8A0964D9E; Mon, 15 Mar 2021 13:51:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1615816303; bh=+BIlPAZ2Vr8nw75QH4LHz5LqpPdXI0+6isk0ygUkL3U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qseNXZnkK9rROY8OB4iQubMB9JDLhkaaxooFBeEKM3coajSvaULa/u/T2t/OU94t0 oMUqB5PGbYDCDI8WAgJjDKaL3aDDs5M/d4s5FL5NTSrOIBkjSMeuqPv2p44doO+nDQ RDTxKT0dZSxzrC1CFS8CVDY9zj1BpSedcWtY7EvZIOKOwQxkG/jqDM8PYQIZh2V9bR QYwdkupTIRNmpqVhuTcOtcb2Kse1+BObzwSJxRtBqvQ5i080CHfN7gulShypikw5dG gNHh8Me63fkQSJfj/uQ+f47fRRLW0HJhWukjym3ERxXOG/gEzrbBYhsFk4bm5UHC2n wchXdu6VelJUg== Date: Mon, 15 Mar 2021 15:51:17 +0200 From: Jarkko Sakkinen To: Kai Huang Cc: Sean Christopherson , kvm@vger.kernel.org, linux-sgx@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, luto@kernel.org, dave.hansen@intel.com, rick.p.edgecombe@intel.com, haitao.huang@intel.com, pbonzini@redhat.com, bp@alien8.de, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com Subject: Re: [PATCH v2 07/25] x86/sgx: Initialize virtual EPC driver even when SGX driver is disabled Message-ID: References: <20210315161317.9c72479dfcde4e22078abcd2@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-kernel@vger.kernel.org On Mon, Mar 15, 2021 at 03:04:59PM +0200, Jarkko Sakkinen wrote: > On Mon, Mar 15, 2021 at 04:13:17PM +1300, Kai Huang wrote: > > On Sun, 14 Mar 2021 17:27:18 +0200 Jarkko Sakkinen wrote: > > > On Sun, Mar 14, 2021 at 05:25:26PM +0200, Jarkko Sakkinen wrote: > > > > On Sat, Mar 13, 2021 at 09:07:36PM +0200, Jarkko Sakkinen wrote: > > > > > On Sat, Mar 13, 2021 at 09:05:36PM +0200, Jarkko Sakkinen wrote: > > > > > > On Fri, Mar 12, 2021 at 01:44:58PM -0800, Sean Christopherson wrote: > > > > > > > On Tue, Mar 09, 2021, Kai Huang wrote: > > > > > > > > Modify sgx_init() to always try to initialize the virtual EPC driver, > > > > > > > > even if the SGX driver is disabled. The SGX driver might be disabled > > > > > > > > if SGX Launch Control is in locked mode, or not supported in the > > > > > > > > hardware at all. This allows (non-Linux) guests that support non-LC > > > > > > > > configurations to use SGX. > > > > > > > > > > > > > > > > Acked-by: Dave Hansen > > > > > > > > Signed-off-by: Kai Huang > > > > > > > > --- > > > > > > > > arch/x86/kernel/cpu/sgx/main.c | 10 +++++++++- > > > > > > > > 1 file changed, 9 insertions(+), 1 deletion(-) > > > > > > > > > > > > > > > > diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c > > > > > > > > index 44fe91a5bfb3..8c922e68274d 100644 > > > > > > > > --- a/arch/x86/kernel/cpu/sgx/main.c > > > > > > > > +++ b/arch/x86/kernel/cpu/sgx/main.c > > > > > > > > @@ -712,7 +712,15 @@ static int __init sgx_init(void) > > > > > > > > goto err_page_cache; > > > > > > > > } > > > > > > > > > > > > > > > > - ret = sgx_drv_init(); > > > > > > > > + /* > > > > > > > > + * Always try to initialize the native *and* KVM drivers. > > > > > > > > + * The KVM driver is less picky than the native one and > > > > > > > > + * can function if the native one is not supported on the > > > > > > > > + * current system or fails to initialize. > > > > > > > > + * > > > > > > > > + * Error out only if both fail to initialize. > > > > > > > > + */ > > > > > > > > + ret = !!sgx_drv_init() & !!sgx_vepc_init(); > > > > > > > > > > > > > > I love this code. > > > > > > > > > > > > > > Reviewed-by: Sean Christopherson > > > > > > > > > > > > I'm still wondering why this code let's go through when sgx_drv_init() > > > > > > succeeds and sgx_vepc_init() fails. > > > > > > > > > > > > The inline comment explains only the mirrored case (which does make > > > > > > sense). > > > > > > > > > > I.e. if sgx_drv_init() succeeds, I'd expect that sgx_vepc_init() must > > > > > succeed. Why expect legitly anything else? > > > > > > > > Apologies coming with these ideas at this point, but here is what this > > > > led me. > > > > > > > > I think that the all this complexity comes from a bad code structure. > > > > > > > > So, what is essentially happening here: > > > > > > > > - We essentially want to make EPC always work. > > > > - Driver optionally. > > > > > > > > So what this sums to is something like: > > > > > > > > ret = sgx_epc_init(); > > > > if (ret) { > > > > pr_err("EPC initialization failed.\n"); > > > > return ret; > > > > } > > > > > > > > ret = sgx_drv_init(); > > > > if (ret) > > > > pr_info("Driver could not be initialized.\n"); > > > > > > > > /* continue */ > > > > > > > > I.e. I think there should be a single EPC init, which does both EPC > > > > bootstrapping and vepc, and driver initialization comes after that. > > > > > > In other words, from SGX point of view, the thing that KVM needs is > > > to cut out EPC and driver part into different islands. How this is now > > > implemented in the current patch set is half-way there but not yet what > > > it should be. > > > > Well conceptually, SGX virtualization and SGX driver are two independently > > functionalities can be enabled separately, although they both requires some > > come functionalities, such as /dev/sgx_provision, which we have moved to > > sgx/main.c exactly for this purpose. THerefore, conceptually, it is bad to make > > assumption that, if SGX virtualization initialization succeeded, SGX driver > > must succeed -- we can potentially add more staff in SGX virtualization in the > > future.. > > > > If the name sgx_vepc_init() confuses you, I can rename it to sgx_virt_init(). > > I don't understand what would be the bad thing here. Can you open that > up please? I'm neither capable of predicting the future... Right, so since vepc_init() does only just device file initialization the current function structure is fine. I totally forgot that sgx_drv_init() does not call EPC initialization when I wrote the above :-) We refactored during the inital cycle the driver so many times that I sometimes fix up thing, sorry about. To meld this into code: ret = sgx_vepc_init(); if (ret != -ENODEV) { pr_err("vEPC initialization failed with %d.\n", ret); return ret; } ret = sgx_drv_init(); if (ret != ENODEV) pr_info("Driver initialization failed %d.\n", ret); This would also give more accurate information how far the initialization went. /Jarkko