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=-7.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 B6F1BC433DB for ; Fri, 22 Jan 2021 10:48:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6DBBF223C8 for ; Fri, 22 Jan 2021 10:48:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727463AbhAVKsU (ORCPT ); Fri, 22 Jan 2021 05:48:20 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:48765 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727128AbhAVKpC (ORCPT ); Fri, 22 Jan 2021 05:45:02 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611312215; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=GOiwNG6fgOv20bcfxuNZKLeDFXi6SHU3aWeO6DKQNDI=; b=BRdz02P8rwGXF5NA0gJvafSdWk3XUvHYINtJbgVM4RkodMRSU0709eBFuI6jHZwsWhaHlS 6JX6hzNLX0h7JzNqzTIF/ARQ5K3qiJGaMuKIfKBD+oLzMth+L9InI4iadMPntSM/3JmccG 6uawINRbNijmIb5woGU2D1e96TCw0Vo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-533-0UHyWJOsNFCMDQ649xP5OA-1; Fri, 22 Jan 2021 05:43:31 -0500 X-MC-Unique: 0UHyWJOsNFCMDQ649xP5OA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1EE6880BCB4; Fri, 22 Jan 2021 10:43:29 +0000 (UTC) Received: from [10.36.114.142] (ovpn-114-142.ams2.redhat.com [10.36.114.142]) by smtp.corp.redhat.com (Postfix) with ESMTP id 845805D9CA; Fri, 22 Jan 2021 10:43:26 +0000 (UTC) Subject: Re: [PATCH V3 1/3] mm/memory_hotplug: Prevalidate the address range being added with platform From: David Hildenbrand To: Anshuman Khandual , linux-mm@kvack.org, akpm@linux-foundation.org, hca@linux.ibm.com, catalin.marinas@arm.com Cc: Oscar Salvador , Vasily Gorbik , Will Deacon , Ard Biesheuvel , Mark Rutland , linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org References: <1610975582-12646-1-git-send-email-anshuman.khandual@arm.com> <1610975582-12646-2-git-send-email-anshuman.khandual@arm.com> <9916f217-ec29-33ff-a260-7a26792d23a1@redhat.com> <897c31ba-d3bd-b694-8c87-82e784a60c51@arm.com> <5e133a5e-41bb-9d6b-f76e-a96d3efe0f5e@redhat.com> Organization: Red Hat GmbH Message-ID: <417b574c-309e-6d5d-36e4-9b16d82c54a6@redhat.com> Date: Fri, 22 Jan 2021 11:43:25 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <5e133a5e-41bb-9d6b-f76e-a96d3efe0f5e@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22.01.21 11:42, David Hildenbrand wrote: > On 22.01.21 11:41, Anshuman Khandual wrote: >> >> On 1/22/21 2:48 PM, David Hildenbrand wrote: >>> >>>> +/* >>>> + * Platforms should define arch_get_mappable_range() that provides >>>> + * maximum possible addressable physical memory range for which the >>>> + * linear mapping could be created. The platform returned address >>>> + * range must adhere to these following semantics. >>>> + * >>>> + * - range.start <= range.end >>>> + * - Range includes both end points [range.start..range.end] >>>> + * >>>> + * There is also a fallback definition provided here, allowing the >>>> + * entire possible physical address range in case any platform does >>>> + * not define arch_get_mappable_range(). >>>> + */ >>>> +struct range __weak arch_get_mappable_range(void) >>>> +{ >>>> + struct range memhp_range = { >>>> + .start = 0UL, >>>> + .end = -1ULL, >>>> + }; >>>> + return memhp_range; >>>> +} >>>> + >>>> +struct range memhp_get_pluggable_range(bool need_mapping) >>>> +{ >>>> + const u64 max_phys = (1ULL << (MAX_PHYSMEM_BITS + 1)) - 1; >>> >>> Sorry, thought about that line a bit more, and I think this is just >>> wrong (took me longer to realize as it should). The old code used this >>> calculation to print the limit only (in a wrong way), let's recap: >>> >>> Assume MAX_PHYSMEM_BITS=32 >>> >>> max_phys = (1ULL << (32 + 1)) - 1 = 0x1ffffffffull; >>> >>> Ehm, these are 33 bit. >>> >>> OTOH, old code checked for >>> >>> if (max_addr >> MAX_PHYSMEM_BITS) { >>> >>> Which makes sense, because >>> >>> 0x1ffffffffull >> 32 = 1 >>> >>> results in "true", meaning it's to big, while >>> >>> 0xffffffffull >> 32 = 0 >>> >>> correctly results in "false", meaning the address is fine. >>> >>> >>> >>> So, this should just be >>> >>> const u64 max_phys = 1ULL << MAX_PHYSMEM_BITS; >>> >>> (similarly as calculated in virito-mem code, or in kernel/resource.c) >> >> Should this be 1ULL << MAX_PHYSMEM_BITS - 1 instead ? Currently there are > > Yes, obviously, sorry, forgot the -1. > const u64 max_phys = (1ULL << MAX_PHYSMEM_BITS) - 1; to be precise. -- Thanks, David / dhildenb