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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8DEBC05027 for ; Mon, 23 Jan 2023 10:29:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231768AbjAWK35 (ORCPT ); Mon, 23 Jan 2023 05:29:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53466 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229548AbjAWK34 (ORCPT ); Mon, 23 Jan 2023 05:29:56 -0500 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4D90013D42; Mon, 23 Jan 2023 02:29:54 -0800 (PST) Received: from pps.filterd (m0187473.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 30N9JnCG015251; Mon, 23 Jan 2023 10:29:54 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=date : from : to : cc : subject : message-id : in-reply-to : references : mime-version : content-type : content-transfer-encoding; s=pp1; bh=RWwKngLyZRUeCYsnMNQWIAHgwZplc5GGnn7Z4wEhdoU=; b=GRVbSB4FHpJC34JC7phDKNNmrsXj9YCx34bzIOhSJzel9DoYE/Mq+48A9lnMBSgLNCrX R18hpgXN7dfCMGwFV7/NvdW/XXLQ4TnIVfkcbcR4QQatFbfp7an/UpQ9Fva78DYRLFb+ scFOeKZEDexebHmPEjEz63wir+QH6s+tLCd6DucFV9jrI2sQ2DpvIqiHBfMPGvtwc8Xs +KDAjzH+KGx1omTKlnndSXTNlMpG1EdD5EntmCgV2mJ65Kl5I7/znFHdBhwwcSRMVpkW 0zcJ9Mey9pAgPvLnG0JiUzox7uMapRVvvQrXAF8qIbWiWKs0Ux9RjkmpEHzr4vQ2brPn 7g== Received: from ppma06ams.nl.ibm.com (66.31.33a9.ip4.static.sl-reverse.com [169.51.49.102]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3n9qgs9k46-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 23 Jan 2023 10:29:53 +0000 Received: from pps.filterd (ppma06ams.nl.ibm.com [127.0.0.1]) by ppma06ams.nl.ibm.com (8.17.1.19/8.17.1.19) with ESMTP id 30N5FK51014950; Mon, 23 Jan 2023 10:29:51 GMT Received: from smtprelay07.fra02v.mail.ibm.com ([9.218.2.229]) by ppma06ams.nl.ibm.com (PPS) with ESMTPS id 3n87afa4mc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 23 Jan 2023 10:29:51 +0000 Received: from smtpav04.fra02v.mail.ibm.com (smtpav04.fra02v.mail.ibm.com [10.20.54.103]) by smtprelay07.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 30NATg2T34799942 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 23 Jan 2023 10:29:42 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 9F00F2004B; Mon, 23 Jan 2023 10:29:42 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 680AD20043; Mon, 23 Jan 2023 10:29:42 +0000 (GMT) Received: from p-imbrenda (unknown [9.152.224.56]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 23 Jan 2023 10:29:42 +0000 (GMT) Date: Mon, 23 Jan 2023 11:29:41 +0100 From: Claudio Imbrenda To: Nico Boehr Cc: borntraeger@linux.ibm.com, frankja@linux.ibm.com, kvm@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [PATCH v1] KVM: s390: disable migration mode when dirty tracking is disabled Message-ID: <20230123112941.5bd57576@p-imbrenda> In-Reply-To: <20230120075406.101436-1-nrb@linux.ibm.com> References: <20230120075406.101436-1-nrb@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 4.1.1 (GTK 3.24.35; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: BXk8QF8RgNYd6qx_AJ1ew-Zow-aOstRt X-Proofpoint-GUID: BXk8QF8RgNYd6qx_AJ1ew-Zow-aOstRt X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.930,Hydra:6.0.562,FMLib:17.11.122.1 definitions=2023-01-23_05,2023-01-23_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 mlxscore=0 malwarescore=0 bulkscore=0 clxscore=1015 priorityscore=1501 phishscore=0 adultscore=0 impostorscore=0 spamscore=0 mlxlogscore=999 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2212070000 definitions=main-2301230094 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, 20 Jan 2023 08:54:06 +0100 Nico Boehr wrote: > Migration mode is a VM attribute which enables tracking of changes in > storage attributes (PGSTE). It assumes dirty tracking is enabled on all > memslots to keep a dirty bitmap of pages with changed storage attributes. > > When enabling migration mode, we currently check that dirty tracking is > enabled for all memslots. However, userspace can disable dirty tracking > without disabling migration mode. > > Since migration mode is pointless with dirty tracking disabled, disable > migration mode whenever userspace disables dirty tracking on any slot. > > Also update the documentation to clarify that dirty tracking must be > enabled when enabling migration mode, which is already enforced by the > code in kvm_s390_vm_start_migration(). > > To disable migration mode, slots_lock should be held, which is taken > in kvm_set_memory_region() and thus held in > kvm_arch_prepare_memory_region(). > > Restructure the prepare code a bit so all the sanity checking is done > before disabling migration mode. This ensures migration mode isn't > disabled when some sanity check fails. > > Cc: stable@vger.kernel.org > Fixes: 190df4a212a7 ("KVM: s390: CMMA tracking, ESSA emulation, migration mode") > Signed-off-by: Nico Boehr Reviewed-by: Claudio Imbrenda > --- > Documentation/virt/kvm/devices/vm.rst | 4 +++ > arch/s390/kvm/kvm-s390.c | 41 ++++++++++++++++++--------- > 2 files changed, 32 insertions(+), 13 deletions(-) > > diff --git a/Documentation/virt/kvm/devices/vm.rst b/Documentation/virt/kvm/devices/vm.rst > index 60acc39e0e93..147efec626e5 100644 > --- a/Documentation/virt/kvm/devices/vm.rst > +++ b/Documentation/virt/kvm/devices/vm.rst > @@ -302,6 +302,10 @@ Allows userspace to start migration mode, needed for PGSTE migration. > Setting this attribute when migration mode is already active will have > no effects. > > +Dirty tracking must be enabled on all memslots, else -EINVAL is returned. When > +dirty tracking is disabled on any memslot, migration mode is automatically > +stopped. > + > :Parameters: none > :Returns: -ENOMEM if there is not enough free memory to start migration mode; > -EINVAL if the state of the VM is invalid (e.g. no memory defined); > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index e4890e04b210..4785f002cd93 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -5628,28 +5628,43 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, > enum kvm_mr_change change) > { > gpa_t size; > + int rc; > > /* When we are protected, we should not change the memory slots */ > if (kvm_s390_pv_get_handle(kvm)) > return -EINVAL; > > - if (change == KVM_MR_DELETE || change == KVM_MR_FLAGS_ONLY) > - return 0; > + if (change != KVM_MR_DELETE && change != KVM_MR_FLAGS_ONLY) { > + /* A few sanity checks. We can have memory slots which have to be > + * located/ended at a segment boundary (1MB). The memory in userland is > + * ok to be fragmented into various different vmas. It is okay to mmap() > + * and munmap() stuff in this slot after doing this call at any time > + */ > > - /* A few sanity checks. We can have memory slots which have to be > - located/ended at a segment boundary (1MB). The memory in userland is > - ok to be fragmented into various different vmas. It is okay to mmap() > - and munmap() stuff in this slot after doing this call at any time */ > + if (new->userspace_addr & 0xffffful) > + return -EINVAL; > > - if (new->userspace_addr & 0xffffful) > - return -EINVAL; > + size = new->npages * PAGE_SIZE; > + if (size & 0xffffful) > + return -EINVAL; > > - size = new->npages * PAGE_SIZE; > - if (size & 0xffffful) > - return -EINVAL; > + if ((new->base_gfn * PAGE_SIZE) + size > kvm->arch.mem_limit) > + return -EINVAL; > + } > > - if ((new->base_gfn * PAGE_SIZE) + size > kvm->arch.mem_limit) > - return -EINVAL; > + /* Turn off migration mode when userspace disables dirty page logging. > + * Migration mode expects dirty page logging being enabled to store > + * its dirty bitmap. > + */ > + if (kvm->arch.migration_mode) { > + if ((old->flags & KVM_MEM_LOG_DIRTY_PAGES) && > + !(new->flags & KVM_MEM_LOG_DIRTY_PAGES)) { > + rc = kvm_s390_vm_stop_migration(kvm); > + > + if (rc) > + pr_warn("Failed to stop migration mode\n"); > + } > + } > > return 0; > }