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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,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 B0056C432BE for ; Thu, 19 Aug 2021 14:12:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9274C61154 for ; Thu, 19 Aug 2021 14:12:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240567AbhHSOMf (ORCPT ); Thu, 19 Aug 2021 10:12:35 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:55008 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240264AbhHSOMe (ORCPT ); Thu, 19 Aug 2021 10:12:34 -0400 Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 17JE3eeq012849; Thu, 19 Aug 2021 10:11:58 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=pp1; bh=UMnRDRYOJDpDifj1IXkiSVngbPMsSJRp2DIFs9Zi6ak=; b=ZTihp2JD7yPZVzjeccaXpjt/tawvxt6janDGJxxoOBcEsLvVZbAWLShx4z/L9Xh2SgIX 0gKINjpVFw/og8yx12OFV1J963paqbKlGMaPrHf+Dn69+JDojL70H49VS3Q67YL6thzp uCiPc4O2g6zzeeWuwdBUC8xWaGfeknuZBCrG9BIGKeu4od3h0PGbLPlZcjg2ppqahTy8 tHjFacG6dzay0282yXOKCyvw2hIwwHGGgQ6oKfEetxAds+VgREZg/mGsmvZZ+alFqTtn B1N2r9UYQ395c9Xjo47IdQvXAejXMtpA9ebWQEHf9fFbRmwM7uQpjxDJlmJMnI1/yBL/ 7A== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 3ahqjc2qtu-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 19 Aug 2021 10:11:57 -0400 Received: from m0098404.ppops.net (m0098404.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 17JE3k6N013286; Thu, 19 Aug 2021 10:11:57 -0400 Received: from ppma02fra.de.ibm.com (47.49.7a9f.ip4.static.sl-reverse.com [159.122.73.71]) by mx0a-001b2d01.pphosted.com with ESMTP id 3ahqjc2qt0-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 19 Aug 2021 10:11:57 -0400 Received: from pps.filterd (ppma02fra.de.ibm.com [127.0.0.1]) by ppma02fra.de.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 17JE8sTT008623; Thu, 19 Aug 2021 14:11:55 GMT Received: from b06cxnps3074.portsmouth.uk.ibm.com (d06relay09.portsmouth.uk.ibm.com [9.149.109.194]) by ppma02fra.de.ibm.com with ESMTP id 3ae5f8f7yf-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 19 Aug 2021 14:11:54 +0000 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 17JEBpbZ56689046 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 19 Aug 2021 14:11:51 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2B7004C058; Thu, 19 Aug 2021 14:11:51 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A6FC54C046; Thu, 19 Aug 2021 14:11:50 +0000 (GMT) Received: from localhost.localdomain (unknown [9.145.148.15]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 19 Aug 2021 14:11:50 +0000 (GMT) Subject: Re: [PATCH 1/2] KVM: s390: gaccess: Cleanup access to guest frames To: Janis Schoetterl-Glausch , David Hildenbrand , Janis Schoetterl-Glausch , kvm@vger.kernel.org, borntraeger@de.ibm.com, imbrenda@linux.ibm.com, Heiko Carstens , Vasily Gorbik Cc: cohuck@redhat.com, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210816150718.3063877-1-scgl@linux.ibm.com> <20210816150718.3063877-2-scgl@linux.ibm.com> <584ca757-4eb4-491e-a4cd-7bc60fb04b61@linux.ibm.com> <745fb5fc-175b-5920-5c56-db4ca8bc2488@linux.vnet.ibm.com> From: Janosch Frank Message-ID: Date: Thu, 19 Aug 2021 16:11:50 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <745fb5fc-175b-5920-5c56-db4ca8bc2488@linux.vnet.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: cu3Do8jpXOG6wIJf4g8l8q_ek_gIi0NU X-Proofpoint-ORIG-GUID: 4gFBLpVlF_CT03WCJlJzvtaL2zbkFAi9 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-08-19_04:2021-08-17,2021-08-19 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 suspectscore=0 mlxlogscore=999 adultscore=0 phishscore=0 bulkscore=0 impostorscore=0 priorityscore=1501 lowpriorityscore=0 mlxscore=0 spamscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108190083 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/19/21 3:53 PM, Janis Schoetterl-Glausch wrote: > On 8/18/21 10:06 AM, Janosch Frank wrote: >> On 8/18/21 9:54 AM, David Hildenbrand wrote: >>> On 16.08.21 17:07, Janis Schoetterl-Glausch wrote: >>>> Introduce a helper function for guest frame access. >>>> Rewrite the calculation of the gpa and the length of the segment >>>> to be more readable. >>>> >>>> Signed-off-by: Janis Schoetterl-Glausch >> [...] >>>> - unsigned long _len, gpa; >>>> + unsigned long gpa; >>>> + unsigned int seg; >>>> int rc = 0; >>>> >>>> while (len && !rc) { >>>> gpa = kvm_s390_real_to_abs(vcpu, gra); >>>> - _len = min(PAGE_SIZE - (gpa & ~PAGE_MASK), len); >>>> - if (mode) >>>> - rc = write_guest_abs(vcpu, gpa, data, _len); >>>> - else >>>> - rc = read_guest_abs(vcpu, gpa, data, _len); >>>> - len -= _len; >>>> - gra += _len; >>>> - data += _len; >>>> + seg = min(PAGE_SIZE - offset_in_page(gpa), len); >>> >>> What does "seg" mean? I certainly know when "len" means -- which is also >>> what the function eats. >> >> What does "_len" mean especially in contrast to "len"? >> >> "seg" is used in the common kvm guest access functions so it's at least >> consistent although I share the sentiment that it's not a great name for >> the length we access inside the page. >> >> Originally I suggested "len_in_page" if you have a better name I'd >> expect we'll both be happy to discuss it :-) > > fragment_len ? Sounds good to me >> >>> >>>> + rc = access_guest_frame(vcpu->kvm, mode, gpa, data, seg); >>>> + len -= seg; >>>> + gra += seg; >>>> + data += seg; >>>> } >>>> return rc; >>>> } >>>> >>> >>> >> >