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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 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 AC865C11F66 for ; Thu, 1 Jul 2021 02:44:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 89DC46140A for ; Thu, 1 Jul 2021 02:44:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238669AbhGACrU (ORCPT ); Wed, 30 Jun 2021 22:47:20 -0400 Received: from out30-43.freemail.mail.aliyun.com ([115.124.30.43]:45518 "EHLO out30-43.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238056AbhGACrT (ORCPT ); Wed, 30 Jun 2021 22:47:19 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R211e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04394;MF=yaohuiwang@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0UeDiCxH_1625107487; Received: from Dillions-MBP-16.local(mailfrom:yaohuiwang@linux.alibaba.com fp:SMTPD_---0UeDiCxH_1625107487) by smtp.aliyun-inc.com(127.0.0.1); Thu, 01 Jul 2021 10:44:48 +0800 From: Yaohui Wang Subject: Re: [PATCH v3 0/2] x86/ioremap: fix boundary calculation and boundary judgment issues for ioremap() To: dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, Thomas Gleixner , mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com Cc: linux-kernel@vger.kernel.org, yaohuiwang@linux.alibaba.com References: <20210621123419.2976-1-yaohuiwang@linux.alibaba.com> Message-ID: <55fa4f7e-356b-8b41-0e06-efa5a065277a@linux.alibaba.com> Date: Thu, 1 Jul 2021 10:44:47 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210621123419.2976-1-yaohuiwang@linux.alibaba.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, maintainers, It's been 10 days since I sent the patches at Jun 21st. Would you please help to review them? Wish to hear your feedbacks, Thanks! Yaohui On 2021/6/21 20:34, Yaohui Wang wrote: > ioremap_xxx() functions should fail if the memory address range contains > normal RAM. But due to some boundary calculation and boundary judgment > issues, the RAM check may be omitted for the very start or the very end > page in the memory range. As a consequence, ioremap_xxx() can be applied > to normal RAM pages by mistake. This raises the risk of misusing > ioremap_xxx() functions on normal RAM ranges, and may incur terrible > performance issues. > > For example, suppose [phys_addr ~ phys_addr + PAGE_SIZE - 1] is a normal > RAM page. Calling ioremap(phys_addr, PAGE_SIZE-1) will succeed (but it > should not). This will set the cache flag of the phys_addr's directing > mapping pte to be PCD. What's worse, iounmap() won't revert this cache > flag in the directing mapping. So the pte in the directing mapping keeps > polluted until workarounds are applied (by invoking ioremap_cache() on > phys_addr) to fix the cache bit. If there is important data/code in the > polluted page, which is accessed frequently, then the performance of the > machine will drop terribly. > > These two patches aim to address this issue. > > Yahui Wang (2): > x86/ioremap: fix the pfn calculation mistake in __ioremap_check_ram() > kernel/resource: fix boundary judgment issues in find_next_iomem_res() > and __walk_iomem_res_desc() > > arch/x86/mm/ioremap.c | 16 ++++++++-------- > kernel/resource.c | 4 ++-- > 2 files changed, 10 insertions(+), 10 deletions(-) > > > base-commit: 13311e74253fe64329390df80bed3f07314ddd61 >