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 5624BC43603 for ; Wed, 18 Dec 2019 11:40:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 27AD3227BF for ; Wed, 18 Dec 2019 11:40:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726831AbfLRLkm (ORCPT ); Wed, 18 Dec 2019 06:40:42 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:41784 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726141AbfLRLkm (ORCPT ); Wed, 18 Dec 2019 06:40:42 -0500 Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id xBIBbQqu027269 for ; Wed, 18 Dec 2019 06:40:40 -0500 Received: from e06smtp04.uk.ibm.com (e06smtp04.uk.ibm.com [195.75.94.100]) by mx0a-001b2d01.pphosted.com with ESMTP id 2wyfhf9hvc-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 18 Dec 2019 06:40:40 -0500 Received: from localhost by e06smtp04.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 18 Dec 2019 11:40:31 -0000 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id xBIBeUUp51511492 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 18 Dec 2019 11:40:30 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AC0784C044; Wed, 18 Dec 2019 11:40:30 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0F3844C05A; Wed, 18 Dec 2019 11:40:30 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.152.224.119]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 18 Dec 2019 11:40:29 +0000 (GMT) Subject: Re: [PATCH v4 00/19] KVM: Dynamically size memslot arrays To: Sean Christopherson , James Hogan , Paul Mackerras , Janosch Frank , Paolo Bonzini , Marc Zyngier Cc: David Hildenbrand , Cornelia Huck , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , James Morse , Julien Thierry , Suzuki K Poulose , linux-mips@vger.kernel.org, kvm-ppc@vger.kernel.org, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, Christoffer Dall , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= References: <20191217204041.10815-1-sean.j.christopherson@intel.com> From: Christian Borntraeger Autocrypt: addr=borntraeger@de.ibm.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 MIME-Version: 1.0 In-Reply-To: <20191217204041.10815-1-sean.j.christopherson@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 19121811-0016-0000-0000-000002D623BE X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19121811-0017-0000-0000-0000333861B2 Message-Id: <595b5ecc-d18b-3973-7041-59e58d7f1cc7@de.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2019-12-18_03:2019-12-17,2019-12-18 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 adultscore=0 clxscore=1015 priorityscore=1501 malwarescore=0 bulkscore=0 impostorscore=0 lowpriorityscore=0 suspectscore=0 mlxlogscore=999 spamscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-1912180097 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 17.12.19 21:40, Sean Christopherson wrote: > The end goal of this series is to dynamically size the memslot array so > that KVM allocates memory based on the number of memslots in use, as > opposed to unconditionally allocating memory for the maximum number of > memslots. On x86, each memslot consumes 88 bytes, and so with 2 address > spaces of 512 memslots, each VM consumes ~90k bytes for the memslots. > E.g. given a VM that uses a total of 30 memslots, dynamic sizing reduces > the memory footprint from 90k to ~2.6k bytes. > > The changes required to support dynamic sizing are relatively small, > e.g. are essentially contained in patches 17/19 and 18/19. > > Patches 2-16 clean up the memslot code, which has gotten quite crusty, > especially __kvm_set_memory_region(). The clean up is likely not strictly > necessary to switch to dynamic sizing, but I didn't have a remotely > reasonable level of confidence in the correctness of the dynamic sizing > without first doing the clean up. > > The only functional change in v4 is the addition of an x86-specific bug > fix in x86's handling of KVM_MR_MOVE. The bug fix is not directly related > to dynamically allocating memslots, but it has subtle and hidden conflicts > with the cleanup patches, and the fix is higher priority than anything > else in the series, i.e. should be merged first. > > On non-x86 architectures, v3 and v4 should be functionally equivalent, > the only non-x86 change in v4 is the dropping of a "const" in > kvm_arch_commit_memory_region(). I gave this series a quick spin and it still seems to work on s390 (minus the selftest).