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=-5.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,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 5D641C433DB for ; Mon, 15 Mar 2021 10:34:09 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 D58D664E12 for ; Mon, 15 Mar 2021 10:34:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D58D664E12 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:CC:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=DUHTXl1fnJIm1SbtcxaE+GV5dIo8b2aaDgS8oDYO9ZY=; b=S1sbSTZrPUfhwpu6sdx0NAFZ1 FCGQ+B4xwC0oFLyYGQ3ITlPAmtBF9pyXli67j7DgJ3SIDRI3W+PxbH3DwNBw5csXI9dkncbFGvcpU e4uF+NBZ/N7lyDFk1WWobHt6y8apb1RQYkJonenmnGgLLrwi9IJanKuLaJNRb+Q0g3G11Nhwelp+T qr02qhRNsQcdQ5el5MorK+ULrrQZM3z1QtYRtHCxFZMc6rD3Li6gaoO+KVtNXEBJalaFowZnUl+RC CDbRQpThdM1zRsBEYaitztMrX7QMCOVcxGYAMiT/6DNt5T3jZZEdsB8PiwMIiVlBFuMs+1bFbcAB3 2j6T3nu/g==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lLkVf-00FWnO-P4; Mon, 15 Mar 2021 10:31:40 +0000 Received: from frasgout.his.huawei.com ([185.176.79.56]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lLkVI-00FWkg-Ni for linux-arm-kernel@lists.infradead.org; Mon, 15 Mar 2021 10:31:19 +0000 Received: from fraeml737-chm.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4DzXdw48HTz680Cl; Mon, 15 Mar 2021 18:26:44 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml737-chm.china.huawei.com (10.206.15.218) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Mon, 15 Mar 2021 11:31:15 +0100 Received: from [10.210.166.140] (10.210.166.140) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Mon, 15 Mar 2021 10:31:14 +0000 Subject: Re: arm64 syzbot instances To: Dmitry Vyukov CC: Arnd Bergmann , Mark Rutland , "Marc Zyngier" , Will Deacon , Ard Biesheuvel , Linux ARM , syzkaller , LKML , Peter Maydell , =?UTF-8?Q?Alex_Benn=c3=a9e?= , Jiahui Cen References: <48347b4d-9194-16f2-95a0-c3eb55ca9a80@huawei.com> From: John Garry Message-ID: <56d33822-e577-c8a8-673b-675d6920c379@huawei.com> Date: Mon, 15 Mar 2021 10:29:08 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Originating-IP: [10.210.166.140] X-ClientProxiedBy: lhreml718-chm.china.huawei.com (10.201.108.69) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210315_103117_377410_29E5BA61 X-CRM114-Status: GOOD ( 22.36 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 15/03/2021 10:01, Dmitry Vyukov wrote: > On Mon, Mar 15, 2021 at 10:45 AM John Garry wrote: >>>> It does not happen too often on syzbot so far, so let's try to do the >>>> right thing first. >>>> I've filed:https://bugs.launchpad.net/qemu/+bug/1918917 >>>> with a link to this thread. To be fair, I don't fully understand what >>>> I am talking about, I hope I proxied your description properly. >>> Thanks, looks good. I provided a little more detail in a comment there. >>> >>> Arnd >>> . >>> >> From looking at the bug report, my impression is that this is a qemu >> issue, as the logical IO space is mapped to the PCI host bridge IO >> space, and qemu does not handle accesses to that CPU addressable region >> at all. As Arnd said. >> >> However, we really should not be accessing logical IO ports 0 or 0x2f8 >> at all via ttyS3 if not enumerated from PCI device at that logical IO >> port. That is what I think anyway, as who knows what device - if any - >> really exists at that location. That is why I had this patch to just >> stop accesses to legacy IO port regions on arm64: >> >> https://lore.kernel.org/lkml/1610729929-188490-2-git-send-email-john.garry@huawei.com/ > Hi John, > > Thanks for the info. > > The patch is from January, but it's not merged yet, right? > It will fix the crash we see, right? > . It's not merged, and it probably would solve this issue. But following discussion with Arnd when it was originally posted, I still need to do some analysis whether it is the proper thing to do. However, as mentioned, the fundamental issue looks like qemu IO port access, so it would be good to check that first. On a related topic, I will cc colleague Jiahui Cen, who I think was doing some work arm on qemu support in a related area, so may share some experience here. Jiahui Cen did have a patch to fix logical PIO code from this work [0], which is not merged, but I don't think would help here. I will cc you on it. Thanks, John [0] https://lore.kernel.org/lkml/006ad6ce-d6b2-59cb-8209-aca3f6e53fec@huawei.com/ _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel