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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED994ECAAA1 for ; Wed, 31 Aug 2022 02:57:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230218AbiHaC5b (ORCPT ); Tue, 30 Aug 2022 22:57:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57916 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229608AbiHaC5a (ORCPT ); Tue, 30 Aug 2022 22:57:30 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BB4BFACA24; Tue, 30 Aug 2022 19:57:29 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 66152B81E3D; Wed, 31 Aug 2022 02:57:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B896C433D6; Wed, 31 Aug 2022 02:57:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1661914647; bh=PfpHO6koOMtihRG7bl3Ls2+YltLO5NIEkNVKrTUIctw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZuyYlmNYAAPSvp/SpUkcUrjgswHVuUS70cGbkXraDRGgbZe9ZR4kJLzCVb20+XpPE 1qQXrpjLTZGaaGbPRv6lZqRHpXSWhcmhaMs5uywY0K06bknYOXeTXYZDEfG777z0B2 EVTaPM+jIigC6a/QGwZI3YX1LoFeHUuoeVjznRwoEQb9HWxu7MWzCJU4gKaTqz6ZgB UonQ1IG88QkxcgYmNorSKaihl7sCI4dXJNQ7eWDI+/niidVSNxHKz3pYhY8zvteh1S f+cp0fWPUiuA+BpIH+scBFOt/f+yfmEvOCIb6bOje4n5oX75vjyZAYAcMLtkM6HE+9 dCUv+q8NZTIWg== Date: Wed, 31 Aug 2022 05:57:22 +0300 From: "jarkko@kernel.org" To: "Huang, Kai" Cc: "pmenzel@molgen.mpg.de" , "linux-sgx@vger.kernel.org" , "x86@kernel.org" , "dave.hansen@linux.intel.com" , "Dhanraj, Vijay" , "Chatre, Reinette" , "mingo@redhat.com" , "tglx@linutronix.de" , "bp@alien8.de" , "haitao.huang@linux.intel.com" , "hpa@zytor.com" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 1/6] x86/sgx: Do not consider unsanitized pages an error Message-ID: References: <20220830031206.13449-1-jarkko@kernel.org> <20220830031206.13449-2-jarkko@kernel.org> <1f43e7b9-c101-3872-bd1b-add66933b285@intel.com> <1b3308a364317d36ad41961ea9cfee24aa122f02.camel@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 Wed, Aug 31, 2022 at 02:55:52AM +0000, Huang, Kai wrote: > On Wed, 2022-08-31 at 05:44 +0300, jarkko@kernel.org wrote: > > On Wed, Aug 31, 2022 at 02:35:53AM +0000, Huang, Kai wrote: > > > On Wed, 2022-08-31 at 05:15 +0300, jarkko@kernel.org wrote: > > > > On Wed, Aug 31, 2022 at 01:27:58AM +0000, Huang, Kai wrote: > > > > > On Tue, 2022-08-30 at 15:54 -0700, Reinette Chatre wrote: > > > > > > Hi Jarkko, > > > > > > > > > > > > On 8/29/2022 8:12 PM, Jarkko Sakkinen wrote: > > > > > > > In sgx_init(), if misc_register() for the provision device fails, and > > > > > > > neither sgx_drv_init() nor sgx_vepc_init() succeeds, then ksgxd will be > > > > > > > prematurely stopped. > > > > > > > > > > > > I do not think misc_register() is required to fail for the scenario to > > > > > > be triggered (rather use "or" than "and"?). Perhaps just > > > > > > "In sgx_init(), if a failure is encountered after ksgxd is started > > > > > > (via sgx_page_reclaimer_init()) ...". > > > > > > > > > > IMHO "a failure" might be too vague. For instance, failure to sgx_drv_init() > > > > > won't immediately result in ksgxd to stop prematurally. As long as KVM SGX can > > > > > be initialized successfully, sgx_init() still returns 0. > > > > > > > > > > Btw I was thinking whether we should move sgx_page_reclaimer_init() to the end > > > > > of sgx_init(), after we make sure at least one of the driver and the KVM SGX is > > > > > initialized successfully. Then the code change in this patch won't be necessary > > > > > if I understand correctly. AFAICT there's no good reason to start the ksgxd at > > > > > early stage before we are sure either the driver or KVM SGX will work. > > > > > > > > I would focus fixing the existing flow rather than reinventing the flow. > > > > > > > > It can be made to work, and therefore it is IMHO correct action to take. > > > > > > From another perspective, the *existing flow* is the reason which causes this > > > bug. A real fix is to fix the flow itself. > > > > Any existing flow in part of the kernel can have a bug. That > > does not mean that switching flow would be proper way to fix > > a bug. > > > > BR, Jarkko > > Yes but I think this is only true when the flow is reasonable. If the flow > itself isn't reasonable, we should fix the flow (given it's easy to fix AFAICT). > > Anyway, let us also hear from others. The flow can be made to work without issues, which in the context of a bug fix is exactly what a bug fix should do. Not more or less. You don't gain any measurable value for the user with this switch idea. BR, Jarkko