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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 C78C3C3A5A5 for ; Thu, 5 Sep 2019 07:52:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 99A972082E for ; Thu, 5 Sep 2019 07:52:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732303AbfIEHwu (ORCPT ); Thu, 5 Sep 2019 03:52:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52476 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729366AbfIEHwu (ORCPT ); Thu, 5 Sep 2019 03:52:50 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2A7FD30044CE; Thu, 5 Sep 2019 07:52:49 +0000 (UTC) Received: from [10.36.117.175] (ovpn-117-175.ams2.redhat.com [10.36.117.175]) by smtp.corp.redhat.com (Postfix) with ESMTP id E67405C219; Thu, 5 Sep 2019 07:52:44 +0000 (UTC) Subject: Re: [PATCH] powerpc: Perform a bounds check in arch_add_memory To: Alastair D'Silva , Michal Hocko Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Christophe Leroy , Andrew Morton , Mike Rapoport , "Aneesh Kumar K.V" , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <20190827052047.31547-1-alastair@au1.ibm.com> <20190827062844.GQ7538@dhcp22.suse.cz> <1f2d967a-57a1-d3a3-4eb7-306b43709fee@redhat.com> <7e8e34ece6386bd3b0703f218a3b4688c83886d7.camel@au1.ibm.com> <5ce9f700-8e70-c669-32fa-9598a01eb8ba@redhat.com> <6823c187257b5033bca8905dda17b6c79a4944a6.camel@au1.ibm.com> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwX4EEwECACgFAljj9eoCGwMFCQlmAYAGCwkI BwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEE3eEPcA/4Na5IIP/3T/FIQMxIfNzZshIq687qgG 8UbspuE/YSUDdv7r5szYTK6KPTlqN8NAcSfheywbuYD9A4ZeSBWD3/NAVUdrCaRP2IvFyELj xoMvfJccbq45BxzgEspg/bVahNbyuBpLBVjVWwRtFCUEXkyazksSv8pdTMAs9IucChvFmmq3 jJ2vlaz9lYt/lxN246fIVceckPMiUveimngvXZw21VOAhfQ+/sofXF8JCFv2mFcBDoa7eYob s0FLpmqFaeNRHAlzMWgSsP80qx5nWWEvRLdKWi533N2vC/EyunN3HcBwVrXH4hxRBMco3jvM m8VKLKao9wKj82qSivUnkPIwsAGNPdFoPbgghCQiBjBe6A75Z2xHFrzo7t1jg7nQfIyNC7ez MZBJ59sqA9EDMEJPlLNIeJmqslXPjmMFnE7Mby/+335WJYDulsRybN+W5rLT5aMvhC6x6POK z55fMNKrMASCzBJum2Fwjf/VnuGRYkhKCqqZ8gJ3OvmR50tInDV2jZ1DQgc3i550T5JDpToh dPBxZocIhzg+MBSRDXcJmHOx/7nQm3iQ6iLuwmXsRC6f5FbFefk9EjuTKcLMvBsEx+2DEx0E UnmJ4hVg7u1PQ+2Oy+Lh/opK/BDiqlQ8Pz2jiXv5xkECvr/3Sv59hlOCZMOaiLTTjtOIU7Tq 7ut6OL64oAq+zsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCghCj/CA/lc/LMthqQ773ga uB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseBfDXHA6m4B3mUTWo13nid 0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts6TZ+IrPOwT1hfB4WNC+X 2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiuQmt3yqrmN63V9wzaPhC+ xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKBTccu2AXJXWAE1Xjh6GOC 8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvFFFyAS0Nk1q/7EChPcbRb hJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh2YmnmLRTro6eZ/qYwWkC u8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRkF3TwgucpyPtcpmQtTkWS gDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0LLH63+BrrHasfJzxKXzqg rW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4vq7oFCPsOgwARAQABwsFl BBgBAgAPBQJVy5+RAhsMBQkJZgGAAAoJEE3eEPcA/4NagOsP/jPoIBb/iXVbM+fmSHOjEshl KMwEl/m5iLj3iHnHPVLBUWrXPdS7iQijJA/VLxjnFknhaS60hkUNWexDMxVVP/6lbOrs4bDZ NEWDMktAeqJaFtxackPszlcpRVkAs6Msn9tu8hlvB517pyUgvuD7ZS9gGOMmYwFQDyytpepo YApVV00P0u3AaE0Cj/o71STqGJKZxcVhPaZ+LR+UCBZOyKfEyq+ZN311VpOJZ1IvTExf+S/5 lqnciDtbO3I4Wq0ArLX1gs1q1XlXLaVaA3yVqeC8E7kOchDNinD3hJS4OX0e1gdsx/e6COvy qNg5aL5n0Kl4fcVqM0LdIhsubVs4eiNCa5XMSYpXmVi3HAuFyg9dN+x8thSwI836FoMASwOl C7tHsTjnSGufB+D7F7ZBT61BffNBBIm1KdMxcxqLUVXpBQHHlGkbwI+3Ye+nE6HmZH7IwLwV W+Ajl7oYF+jeKaH4DZFtgLYGLtZ1LDwKPjX7VAsa4Yx7S5+EBAaZGxK510MjIx6SGrZWBrrV TEvdV00F2MnQoeXKzD7O4WFbL55hhyGgfWTHwZ457iN9SgYi1JLPqWkZB0JRXIEtjd4JEQcx +8Umfre0Xt4713VxMygW0PnQt5aSQdMD58jHFxTk092mU+yIHj5LeYgvwSgZN4airXk5yRXl SE+xAvmumFBY Organization: Red Hat GmbH Message-ID: <6ffaaaaf-eaed-0409-61e8-7333f8a43f5a@redhat.com> Date: Thu, 5 Sep 2019 09:52:44 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <6823c187257b5033bca8905dda17b6c79a4944a6.camel@au1.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Thu, 05 Sep 2019 07:52:49 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04.09.19 07:25, Alastair D'Silva wrote: > On Mon, 2019-09-02 at 09:28 +0200, David Hildenbrand wrote: >> On 02.09.19 01:54, Alastair D'Silva wrote: >>> On Tue, 2019-08-27 at 09:13 +0200, David Hildenbrand wrote: >>>> On 27.08.19 08:39, Alastair D'Silva wrote: >>>>> On Tue, 2019-08-27 at 08:28 +0200, Michal Hocko wrote: >>>>>> On Tue 27-08-19 15:20:46, Alastair D'Silva wrote: >>>>>>> From: Alastair D'Silva >>>>>>> >>>>>>> It is possible for firmware to allocate memory ranges >>>>>>> outside >>>>>>> the range of physical memory that we support >>>>>>> (MAX_PHYSMEM_BITS). >>>>>> >>>>>> Doesn't that count as a FW bug? Do you have any evidence of >>>>>> that >>>>>> in >>>>>> the >>>>>> field? Just wondering... >>>>>> >>>>> >>>>> Not outside our lab, but OpenCAPI attached LPC memory is >>>>> assigned >>>>> addresses based on the slot/NPU it is connected to. These >>>>> addresses >>>>> prior to: >>>>> 4ffe713b7587 ("powerpc/mm: Increase the max addressable memory >>>>> to >>>>> 2PB") >>>>> were inaccessible and resulted in bogus sections - see our >>>>> discussion >>>>> on 'mm: Trigger bug on if a section is not found in >>>>> __section_nr'. >>>>> Doing this check here was your suggestion :) >>>>> >>>>> It's entirely possible that a similar problem will occur in the >>>>> future, >>>>> and it's cheap to guard against, which is why I've added this. >>>>> >>>> >>>> If you keep it here, I guess this should be wrapped by a >>>> WARN_ON_ONCE(). >>>> >>>> If we move it to common code (e.g., __add_pages() or >>>> add_memory()), >>>> then >>>> probably not. I can see that s390x allows to configure >>>> MAX_PHYSMEM_BITS, >>>> so the check could actually make sense. >>>> >>> >>> I couldn't see a nice platform indepedent way to determine the >>> allowable address range, but if there is, then I'll move this to >>> the >>> generic code instead. >>> >> >> At least on the !ZONE_DEVICE path we have >> >> __add_memory() -> register_memory_resource() ... >> >> return ERR_PTR(-E2BIG); >> >> >> I was thinking about something like >> >> int add_pages() >> { >> if ((start + size - 1) >> MAX_PHYSMEM_BITS) >> return -E2BIG; >> >> return arch_add_memory(...) >> } >> >> And switching users of arch_add_memory() to add_pages(). However, x86 >> already has an add_pages() function, so that would need some more >> thought. >> >> Maybe simply renaming the existing add_pages() to arch_add_pages(). >> >> add_pages(): Create virtual mapping >> __add_pages(): Don't create virtual mapping >> >> arch_add_memory(): Arch backend for add_pages() >> arch_add_pages(): Arch backend for __add_pages() >> >> It would be even more consistent if we would have arch_add_pages() >> vs. >> __arch_add_pages(). > > Looking a bit further, I think a good course of action would be to add > the check to memory_hotplug.c:check_hotplug_memory_range(). > > This would be the least invasive, and could check both > MAX_POSSIBLE_PHYSMEM_BITS and MAX_PHYSMEM_BITS. You won't be able to catch the memremap path that way, just saying. But at least it would be an easy change. > > With that in mind, we can drop this patch. > -- Thanks, David / dhildenb