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 266CEC43142 for ; Wed, 27 Jun 2018 13:33:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B534A260B2 for ; Wed, 27 Jun 2018 13:33:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B534A260B2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=hisilicon.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 S965286AbeF0Ndd (ORCPT ); Wed, 27 Jun 2018 09:33:33 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:8737 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S964850AbeF0Ndc (ORCPT ); Wed, 27 Jun 2018 09:33:32 -0400 Received: from DGGEMS414-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 18B4BC76695F; Wed, 27 Jun 2018 21:33:17 +0800 (CST) Received: from [127.0.0.1] (10.202.226.42) by DGGEMS414-HUB.china.huawei.com (10.3.19.214) with Microsoft SMTP Server id 14.3.382.0; Wed, 27 Jun 2018 21:33:09 +0800 Subject: Re: KVM guest sometimes failed to boot because of kernel stack overflow if KPTI is enabled on a hisilicon ARM64 platform. To: Will Deacon References: <5B2A6218.3030201@hisilicon.com> <20180620144257.GB27776@arm.com> <5B2A7832.4010502@hisilicon.com> <5B2A7FE1.5040607@hisilicon.com> <5B2B6DEA.2090100@hisilicon.com> <5B3274FC.7000206@hisilicon.com> <20180626174746.GO23375@arm.com> <5B338F7B.9070500@hisilicon.com> <20180627132826.GB30631@arm.com> CC: James Morse , , , Linuxarm , Zhangyi ac , , , "Xiongfanggou (James)" , , , , "Liyuan (Larry, Turing Solution)" , , , , , Hanjun Guo , "Liguozhu (Kenneth)" From: Wei Xu Message-ID: <5B33920A.9070700@hisilicon.com> Date: Wed, 27 Jun 2018 14:32:58 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <20180627132826.GB30631@arm.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.226.42] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Will, On 2018/6/27 14:28, Will Deacon wrote: > On Wed, Jun 27, 2018 at 02:22:03PM +0100, Wei Xu wrote: >> On 2018/6/26 18:47, Will Deacon wrote: >>> If you look at the __idmap_kpti_put_pgtable_ent_ng asm macro, can you try >>> replacing: >>> >>> dc civac, cur_\()\type\()p >>> >>> with: >>> >>> dc ivac, cur_\()\type\()p >>> >>> please? Only do this for the guest kernel, not the host. KVM will upgrade >>> the clean to a clean+invalidate, so it's interesting to see if this has >>> an effect on the behaviour. >> >> Only changed the guest kernel, the guest still failed to boot and the log >> is same with the last mail. >> >> But if I changed to cvac as below for the guest, it is kind of stable. >> dc cvac, cur_\()\type\()p >> >> I have synced with our SoC guys about this and hope we can find the reason. >> Do you have any more suggestion? > > Unfortunately, not. It looks like somehow clean+invalidate is behaving > just as an invalidate, and we're corrupting the page table as a result. > > Hopefully the SoC guys will figure it out. Thanks anyway! I will update here if any news. Best Regards, Wei > > Will > > . >