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=-8.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 EDD85C433E7 for ; Tue, 14 Jul 2020 12:32:25 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CC88021D79 for ; Tue, 14 Jul 2020 12:32:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CC88021D79 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jvK6Z-0001ZO-4V; Tue, 14 Jul 2020 12:32:15 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jvK6Y-0001ZJ-3m for xen-devel@lists.xenproject.org; Tue, 14 Jul 2020 12:32:14 +0000 X-Inumbo-ID: 0b4a43aa-c5ce-11ea-b7bb-bc764e2007e4 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 0b4a43aa-c5ce-11ea-b7bb-bc764e2007e4; Tue, 14 Jul 2020 12:32:13 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 630AEAD3A; Tue, 14 Jul 2020 12:32:15 +0000 (UTC) Subject: Re: [PATCH v7 08/15] x86_64/mm: switch to new APIs in setup_m2p_table To: Hongyan Xia References: <14aec5f25e8226a45dbc6b26fcc9981ea5f66a90.1590750232.git.hongyxia@amazon.com> From: Jan Beulich Message-ID: <625a5450-daca-0837-6977-4b0ae237d988@suse.com> Date: Tue, 14 Jul 2020 14:32:13 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <14aec5f25e8226a45dbc6b26fcc9981ea5f66a90.1590750232.git.hongyxia@amazon.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: xen-devel@lists.xenproject.org, =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , julien@xen.org, Wei Liu , Andrew Cooper Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On 29.05.2020 13:11, Hongyan Xia wrote: > From: Wei Liu > > Avoid repetitive mapping of l2_ro_mpt by keeping it across loops, and > only unmap and map it when crossing 1G boundaries. > > Signed-off-by: Wei Liu > Signed-off-by: Hongyan Xia Reviewed-by: Jan Beulich I do think, however, that ... > @@ -438,32 +443,29 @@ static int setup_m2p_table(struct mem_hotadd_info *info) > > ASSERT(!(l3e_get_flags(l3_ro_mpt[l3_table_offset(va)]) & > _PAGE_PSE)); > - if ( l3e_get_flags(l3_ro_mpt[l3_table_offset(va)]) & > - _PAGE_PRESENT ) > - l2_ro_mpt = l3e_to_l2e(l3_ro_mpt[l3_table_offset(va)]) + > - l2_table_offset(va); > - else > + if ( (l3e_get_flags(l3_ro_mpt[l3_table_offset(va)]) & > + _PAGE_PRESENT) && !l2_ro_mpt) > + l2_ro_mpt = map_l2t_from_l3e(l3_ro_mpt[l3_table_offset(va)]); > + else if ( !l2_ro_mpt ) > { ... this would be slightly neater as if ( l2_ro_mpt ) /* nothing */; else if ( l3e_get_flags(l3_ro_mpt[l3_table_offset(va)]) & _PAGE_PRESENT ) l2_ro_mpt = map_l2t_from_l3e(l3_ro_mpt[l3_table_offset(va)]); else { ... My R-b holds if you would change it like this. Jan