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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 03962C43141 for ; Thu, 21 Jun 2018 08:39:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B8A0820837 for ; Thu, 21 Jun 2018 08:39:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B8A0820837 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932677AbeFUIjZ (ORCPT ); Thu, 21 Jun 2018 04:39:25 -0400 Received: from foss.arm.com ([217.140.101.70]:47112 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753938AbeFUIjB (ORCPT ); Thu, 21 Jun 2018 04:39:01 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 875CD80D; Thu, 21 Jun 2018 01:39:00 -0700 (PDT) Received: from [10.1.206.34] (melchizedek.cambridge.arm.com [10.1.206.34]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C4FF43F246; Thu, 21 Jun 2018 01:38:55 -0700 (PDT) Subject: Re: KVM guest sometimes failed to boot because of kernel stack overflow if KPTI is enabled on a hisilicon ARM64 platform. To: Wei Xu , Will Deacon Cc: catalin.marinas@arm.com, suzuki.poulose@arm.com, dave.martin@arm.com, mark.rutland@arm.com, marc.zyngier@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Linuxarm , Hanjun Guo , xiexiuqi@huawei.com, huangdaode , "Chenxin (Charles)" , "Xiongfanggou (James)" , "Liguozhu (Kenneth)" , Zhangyi ac , jonathan.cameron@huawei.com, Shameerali Kolothum Thodi , John Garry , Salil Mehta , Shiju Jose , "Zhuangyuzeng (Yisen)" , "Wangzhou (B)" , "kongxinwei (A)" , "Liyuan (Larry, Turing Solution)" , libeijian@hisilicon.com References: <5B2A6218.3030201@hisilicon.com> <20180620144257.GB27776@arm.com> <5B2A7832.4010502@hisilicon.com> <5B2A7FE1.5040607@hisilicon.com> From: James Morse Message-ID: Date: Thu, 21 Jun 2018 09:38:53 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <5B2A7FE1.5040607@hisilicon.com> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Will, Wei, On 20/06/18 17:25, Wei Xu wrote: > On 2018/6/20 23:54, James Morse wrote: > I have disabled CONFIG_ARM64_RAS_EXTN and reverted that commit. > But I still got the stack overflow issue sometimes. > Do you have more hint? > The log is as below: >     [    0.000000] Booting Linux on physical CPU 0x0000000000 [0x480fd010] >     [    0.000000] Linux version 4.17.0-45865-g2b31fe7-dirty Could you reproduce this with v4.17? This says there are ~45,000 extra patches, and un-committed changes. None of the hashes so far have been commits in mainline, so we have no idea what this tree is. > (joyx@Turing-Arch-b) (gcc version 4.9.1 20140505 (prerelease) (crosstool-NG > linaro-1.13.1-4.9-2014.05 - Linaro GCC 4.9-2014.05)) #10 SMP PREEMPT Wed Jun 20 > 23:59:05 CST 2018 >     [    0.000000] CPU0: using LPI pending table @0x000000007d860000 >     [    0.000000] GIC: PPI11 is secure or misconfigured >     [    0.000000] arch_timer: WARNING: Invalid trigger for IRQ3, assuming level > low >     [    0.000000] arch_timer: WARNING: Please fix your firmware >     [    0.000000] arch_timer: cp15 timer(s) running at 100.00MHz (virt). (No idea what these mean, but I doubt they are relevant) >     [    0.042421] Insufficient stack space to handle exception! >     [    0.042423] ESR: 0x96000046 -- DABT (current EL) >     [    0.043730] FAR: 0xffff0000093a80e0 >     [    0.044714] Task stack: [0xffff0000093a8000..0xffff0000093ac000] This was a level 2 translation fault on a write, to an address that is within the stack.... >     [    0.051113] IRQ stack: [0xffff000008000000..0xffff000008004000] >     [    0.057610] Overflow stack: [0xffff80003efce2f0..0xffff80003efcf2f0] >     [    0.064003] CPU: 0 PID: 12 Comm: migration/0 Not tainted > 4.17.0-45865-g2b31fe7-dirty #10 >     [    0.072201] Hardware name: linux,dummy-virt (DT) >     [    0.076797] pstate: 604003c5 (nZCv DAIF +PAN -UAO) >     [    0.081727] pc : el1_sync+0x0/0xb0 ... from the vectors. >     [    0.085217] lr : kpti_install_ng_mappings+0x120/0x214 What I think is happening is: we come out of the kpti idmap with the stack unmapped. Shortly after we access the stack, which faults. el1_sync faults as well when it tries to push the registers to the stack, and we keep going until we overflow the stack. I can't reproduce this with kvmtool or qemu in the model. Thanks, James