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 634CBC77B75 for ; Fri, 21 Apr 2023 08:18:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229521AbjDUISK (ORCPT ); Fri, 21 Apr 2023 04:18:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46474 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229882AbjDUISJ (ORCPT ); Fri, 21 Apr 2023 04:18:09 -0400 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8E4852106; Fri, 21 Apr 2023 01:18:07 -0700 (PDT) Received: from pps.filterd (m0353724.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 33L8HPaM005887; 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Fri, 21 Apr 2023 08:18:04 GMT Received: from smtprelay05.fra02v.mail.ibm.com ([9.218.2.225]) by ppma04ams.nl.ibm.com (PPS) with ESMTPS id 3pykj6bw7r-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 21 Apr 2023 08:18:03 +0000 Received: from smtpav07.fra02v.mail.ibm.com (smtpav07.fra02v.mail.ibm.com [10.20.54.106]) by smtprelay05.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 33L8Hw8E66126334 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 21 Apr 2023 08:17:58 GMT Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 22E2A20043; Fri, 21 Apr 2023 08:17:58 +0000 (GMT) Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 9E00620040; Fri, 21 Apr 2023 08:17:57 +0000 (GMT) Received: from p-imbrenda (unknown [9.171.7.117]) by smtpav07.fra02v.mail.ibm.com (Postfix) with SMTP; Fri, 21 Apr 2023 08:17:57 +0000 (GMT) Date: Fri, 21 Apr 2023 10:17:54 +0200 From: Claudio Imbrenda To: Christian Borntraeger Cc: kvm@vger.kernel.org, nrb@linux.ibm.com, nsg@linux.ibm.com, frankja@linux.ibm.com, mhartmay@linux.ibm.com, kvm390-list@tuxmaker.boeblingen.de.ibm.com, linux-s390@vger.kernel.org Subject: Re: [PATCH v1 1/1] KVM: s390: pv: fix asynchronous teardown for small VMs Message-ID: <20230421101754.00955356@p-imbrenda> In-Reply-To: <4e7db9f6-a199-4a95-ea14-13d7803884be@de.ibm.com> References: <20230420160149.51728-1-imbrenda@linux.ibm.com> <4e7db9f6-a199-4a95-ea14-13d7803884be@de.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-GUID: 3WN9cISWKzeuD03Kxb1IEw7nuF6VeyYB X-Proofpoint-ORIG-GUID: 3WN9cISWKzeuD03Kxb1IEw7nuF6VeyYB X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-04-21_02,2023-04-20_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 suspectscore=0 bulkscore=0 priorityscore=1501 mlxscore=0 lowpriorityscore=0 malwarescore=0 spamscore=0 adultscore=0 clxscore=1015 mlxlogscore=999 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2303200000 definitions=main-2304210069 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Fri, 21 Apr 2023 10:07:22 +0200 Christian Borntraeger wrote: > Am 20.04.23 um 18:01 schrieb Claudio Imbrenda: > > On machines without the Destroy Secure Configuration Fast UVC, the > > topmost level of page tables is set aside and freed asynchronously > > as last step of the asynchronous teardown. > > > > Each gmap has a host_to_guest radix tree mapping host (userspace) > > addresses (with 1M granularity) to gmap segment table entries (pmds). > > > > If a guest is smaller than 2GB, the topmost level of page tables is the > > segment table (i.e. there are only 2 levels). Replacing it means that > > the pointers in the host_to_guest mapping would become stale and cause > > all kinds of nasty issues. > > > > This patch fixes the issue by synchronously destroying all guests with > > only 2 levels of page tables in kvm_s390_pv_set_aside. This will > > speed up the process and avoid the issue altogether. > > > > Update s390_replace_asce so it refuses to replace segment type ASCEs. > > > > Signed-off-by: Claudio Imbrenda > > Fixes: fb491d5500a7 ("KVM: s390: pv: asynchronous destroy for reboot") > > --- > > arch/s390/kvm/pv.c | 35 ++++++++++++++++++++--------------- > > arch/s390/mm/gmap.c | 7 +++++++ > > 2 files changed, 27 insertions(+), 15 deletions(-) > > > > diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c > > index e032ebbf51b9..ceb8cb628d62 100644 > > --- a/arch/s390/kvm/pv.c > > +++ b/arch/s390/kvm/pv.c > > @@ -39,6 +39,7 @@ struct pv_vm_to_be_destroyed { > > u64 handle; > > void *stor_var; > > unsigned long stor_base; > > + bool small; > > }; > > > > static void kvm_s390_clear_pv_state(struct kvm *kvm) > > @@ -318,7 +319,11 @@ int kvm_s390_pv_set_aside(struct kvm *kvm, u16 *rc, u16 *rrc) > > if (!priv) > > return -ENOMEM; > > > > - if (is_destroy_fast_available()) { > > + if ((kvm->arch.gmap->asce & _ASCE_TYPE_MASK) == _ASCE_TYPE_SEGMENT) { > > + /* No need to do things asynchronously for VMs under 2GB */ > > + res = kvm_s390_pv_deinit_vm(kvm, rc, rrc); > > + priv->small = true; > > + } else if (is_destroy_fast_available()) { > > res = kvm_s390_pv_deinit_vm_fast(kvm, rc, rrc); > > } else { > > priv->stor_var = kvm->arch.pv.stor_var; > > @@ -335,7 +340,8 @@ int kvm_s390_pv_set_aside(struct kvm *kvm, u16 *rc, u16 *rrc) > > return res; > > } > > > > - kvm_s390_destroy_lower_2g(kvm); > > + if (!priv->small) > > + kvm_s390_destroy_lower_2g(kvm); > > kvm_s390_clear_pv_state(kvm); > > kvm->arch.pv.set_aside = priv; > > > > @@ -418,7 +424,10 @@ int kvm_s390_pv_deinit_cleanup_all(struct kvm *kvm, u16 *rc, u16 *rrc) > > > > /* If a previous protected VM was set aside, put it in the need_cleanup list */ > > if (kvm->arch.pv.set_aside) { > > - list_add(kvm->arch.pv.set_aside, &kvm->arch.pv.need_cleanup); > > + if (((struct pv_vm_to_be_destroyed *)kvm->arch.pv.set_aside)->small) > why do we need a cast here? it's a void * but it's not important, after talking with Marc I have found a much simpler solution (will post soon) > > > + kfree(kvm->arch.pv.set_aside); > > + else > > + list_add(kvm->arch.pv.set_aside, &kvm->arch.pv.need_cleanup); > > kvm->arch.pv.set_aside = NULL; > > } > > > > With the comment added that Marc asked for > > Acked-by: Christian Borntraeger >