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,URIBL_BLOCKED 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 00A72C433E9 for ; Sun, 14 Mar 2021 15:26:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B62CA64EE2 for ; Sun, 14 Mar 2021 15:26:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233791AbhCNP0Y (ORCPT ); Sun, 14 Mar 2021 11:26:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:41480 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232431AbhCNPZs (ORCPT ); Sun, 14 Mar 2021 11:25:48 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8CE4864E2E; Sun, 14 Mar 2021 15:25:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1615735548; bh=jwbcSexfc5OU64cnObvT3+BpkF52QDxPXC4wOw6jhEc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=u5B+HWqQxV1a2ogMRb+1BJ+5tsJ/89bRI9K7nHAPzn9FpQrcaf5q/Cby/vqDi3u3u 0/HueRmp2HG4kpG8KK4vBj3zhnlrcuWzbPREmm8DV4pwj8Kks/bfH9XOy/lJUyO7Ui ose8L/YAjIv4vdYNyR2EvJm3GrPPYhSXHt768z4oL8RX5gPGhz59YimixwaS+Vniq3 +X2jqGeHTs94OgeNNFAHGeihihsUMc1iW1puJMna56aXwWceUIqaEFeMpBaSBBEMjE glrOFW1eyrG5BDpK9vy+IVQsJnejJ8VRNvyBgtoImF4ZQyCXFwmOFRez3X7e3Cv8U4 PREa8oIXYSAgQ== Date: Sun, 14 Mar 2021 17:25:23 +0200 From: Jarkko Sakkinen To: Sean Christopherson Cc: Kai Huang , 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: 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 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. /Jarkko