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 BF759C77B75 for ; Fri, 21 Apr 2023 08:08:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229724AbjDUIIK (ORCPT ); Fri, 21 Apr 2023 04:08:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41226 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229650AbjDUIIJ (ORCPT ); Fri, 21 Apr 2023 04:08:09 -0400 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF5D05FC9; Fri, 21 Apr 2023 01:08:07 -0700 (PDT) Received: from pps.filterd (m0353728.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 33L878uC015168; Fri, 21 Apr 2023 08:08:07 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=message-id : date : mime-version : subject : to : cc : references : from : in-reply-to : content-type : content-transfer-encoding; s=pp1; bh=kAMLC3oMEfc8K6g0PtdgP9CTjQH5R2bPLBwvrFMaLz4=; b=S1IW+4cL53dxXs8BP2ZkfziELtvwfhPcXrC4oWx/UupttHDC684g0MwnfSRDeCUPH9b7 JOLOuo2YSmrIje7cJKwA4sBOBwPw+kYSidHCv4PUZBPG2ZU9NiQMLpEykMffjex2GwAj S8v9jzEmbpPLgYREq9pdsYYtgbLZMv9+hHC319eHNF8L8zLiZsFGw9sZpH4iXg4NpZQH 4ziznAXdppRfm9UEIkLTQ7h3IjcZA4lX1CvVRNYf6S/OlXhoKrzLsgxSVbeoiUqauET0 fpQvFcLWxEjaXHR9ADGlOar3kKnceXfosZh8Om9es6V3PSNNPpAykVmODZu0qp2LSHyD Og== 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 3q3pbb8rfr-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 21 Apr 2023 08:08:05 +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 33K7UVBn031974; Fri, 21 Apr 2023 08:07:27 GMT Received: from smtprelay06.fra02v.mail.ibm.com ([9.218.2.230]) by ppma06ams.nl.ibm.com (PPS) with ESMTPS id 3pyk6fkwfj-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 21 Apr 2023 08:07:27 +0000 Received: from smtpav06.fra02v.mail.ibm.com (smtpav06.fra02v.mail.ibm.com [10.20.54.105]) by smtprelay06.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 33L87NvP20447606 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 21 Apr 2023 08:07:23 GMT Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5D98C20049; Fri, 21 Apr 2023 08:07:23 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E14C620040; Fri, 21 Apr 2023 08:07:22 +0000 (GMT) Received: from [9.179.30.152] (unknown [9.179.30.152]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 21 Apr 2023 08:07:22 +0000 (GMT) Message-ID: <4e7db9f6-a199-4a95-ea14-13d7803884be@de.ibm.com> Date: Fri, 21 Apr 2023 10:07:22 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [PATCH v1 1/1] KVM: s390: pv: fix asynchronous teardown for small VMs To: Claudio Imbrenda , kvm@vger.kernel.org Cc: 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 References: <20230420160149.51728-1-imbrenda@linux.ibm.com> Content-Language: en-US From: Christian Borntraeger In-Reply-To: <20230420160149.51728-1-imbrenda@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: cW5vCwEn10jBZeyJGwzk0rgdhJfhKnOk X-Proofpoint-GUID: cW5vCwEn10jBZeyJGwzk0rgdhJfhKnOk 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 spamscore=0 bulkscore=0 impostorscore=0 priorityscore=1501 malwarescore=0 clxscore=1011 suspectscore=0 adultscore=0 mlxscore=0 lowpriorityscore=0 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 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? > + 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