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 4C4D4C433DB for ; Fri, 22 Jan 2021 09:42:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 07F0A22DBF for ; Fri, 22 Jan 2021 09:42:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727678AbhAVJlq (ORCPT ); Fri, 22 Jan 2021 04:41:46 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:35456 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727425AbhAVJTz (ORCPT ); Fri, 22 Jan 2021 04:19:55 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611307108; 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=+bPNlYTRjqjFp32YO1EEUTJqDvtbUUivvSM0yNsU/3s=; b=RlEhcdj3RNMAeEZiVsCGl2z2KYtHKb9WhSPT8wKRGT3wKKI8QIv+PDYASFFWjiL349bNdo HIKIeglupM3F3XBEDjdfQ6xo78qlRoB9MuAaMBRIeKw1GxWdZamEDOh0Ik88nwZis4av5W W1cGMH5s41xPy5bx+yvQCdpuBQgCYFE= 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-538-xErR3gUGMlq5d42b3Cpd3Q-1; Fri, 22 Jan 2021 04:18:26 -0500 X-MC-Unique: xErR3gUGMlq5d42b3Cpd3Q-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7C8FF190B2A1; Fri, 22 Jan 2021 09:18:24 +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 E8B6010023B9; Fri, 22 Jan 2021 09:18:21 +0000 (UTC) Subject: Re: [PATCH V3 1/3] mm/memory_hotplug: Prevalidate the address range being added with platform 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> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <9916f217-ec29-33ff-a260-7a26792d23a1@redhat.com> Date: Fri, 22 Jan 2021 10:18:21 +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: <1610975582-12646-2-git-send-email-anshuman.khandual@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > +/* > + * 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) > + struct range memhp_range; > + > + if (need_mapping) { > + memhp_range = arch_get_mappable_range(); > + if (memhp_range.start > max_phys) { > + memhp_range.start = 0; > + memhp_range.end = 0; > + } > + memhp_range.end = min_t(u64, memhp_range.end, max_phys); > + } else { > + memhp_range.start = 0; > + memhp_range.end = max_phys; > + } > + return memhp_range; > +} > +EXPORT_SYMBOL_GPL(memhp_get_pluggable_range); -- Thanks, David / dhildenb