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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 F0C74C4361B for ; Thu, 17 Dec 2020 22:46:41 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5D43D23A03 for ; Thu, 17 Dec 2020 22:46:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5D43D23A03 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:40140 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kq22i-0005dI-92 for qemu-devel@archiver.kernel.org; Thu, 17 Dec 2020 17:46:40 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:58276) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kq21o-00055r-TI for qemu-devel@nongnu.org; Thu, 17 Dec 2020 17:45:44 -0500 Received: from mx2.suse.de ([195.135.220.15]:51898) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kq21n-00062s-7h for qemu-devel@nongnu.org; Thu, 17 Dec 2020 17:45:44 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 890B0AC7B; Thu, 17 Dec 2020 22:45:41 +0000 (UTC) Subject: Re: dangers of current NEED_CPU_H, CONFIG_SOFTMMU, CONFIG_USER_ONLY To: Peter Maydell References: <20201211100908.19696-1-cfontana@suse.de> <20201211100908.19696-8-cfontana@suse.de> From: Claudio Fontana Message-ID: Date: Thu, 17 Dec 2020 23:45:40 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=195.135.220.15; envelope-from=cfontana@suse.de; helo=mx2.suse.de X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eduardo Habkost , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Richard Henderson , QEMU Developers , =?UTF-8?Q?Marc-Andr=c3=a9_Lureau?= , Paolo Bonzini , Alex Bennee Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 12/17/20 9:15 PM, Peter Maydell wrote: > On Thu, 17 Dec 2020 at 19:46, Claudio Fontana wrote: >> >> Hi, >> >> I would like to highlight the current dangerous state of NEED_CPU_H / CONFIG_SOFTMMU / CONFIG_USER_ONLY. > >> So our struct TcgCpuOperations in include/hw/core/cpu.h, >> which contains after this series: >> >> #ifndef CONFIG_USER_ONLY >> /** >> * @do_transaction_failed: Callback for handling failed memory transactions >> * (ie bus faults or external aborts; not MMU faults) >> */ >> void (*do_transaction_failed)(CPUState *cpu, hwaddr physaddr, vaddr addr, >> unsigned size, MMUAccessType access_type, >> int mmu_idx, MemTxAttrs attrs, >> MemTxResult response, uintptr_t retaddr); >> /** >> * @do_unaligned_access: Callback for unaligned access handling >> */ >> void (*do_unaligned_access)(CPUState *cpu, vaddr addr, >> MMUAccessType access_type, >> int mmu_idx, uintptr_t retaddr); >> #endif /* !CONFIG_USER_ONLY */ > > Yeah, don't try to ifdef out struct fields in common-compiled code... or should I? Using #ifdef NEED_CPU_H #ifdef CONFIG_SOFTMMU seems to do what I expect. Is it wrong? Thanks, Claudio > >> Note that include/hw/core/cpu.h already uses CONFIG_USER_ONLY in other parts of the header file, and we might have hidden problems as a result we (or at least I) don't know about, >> because code is being compiled in for linux-user which explicitly should not be compiled there. > > The other CONFIG_USER_ONLY checks in that file are only > ifdeffing out prototypes for functions that exist only in > the softmmu build, or providing do-nothing stubs for functions > that are softmmu only. I think they're safe. > >> There are multiple workarounds / fixes possible for my short term problem, >> but would it not be a good idea to fix this problem at its root once and for all? > > What's your proposal for fixing things ? > > Incidentally, this should not be a problem for CONFIG_SOFTMMU, > because that is listed in include/exec/poison.h so trying to > use it in a common (not compiled-per-target) file will give you > a compile error. (So in theory we could make CONFIG_USER_ONLY > a poisoned identifier but that will require some work to > adjust places where we currently use it in "safe" ways...) > > thanks > -- PMM >