From patchwork Thu Feb 27 09:10:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Mueller X-Patchwork-Id: 11408157 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 55C2392A for ; Thu, 27 Feb 2020 09:10:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3EB8F2467F for ; Thu, 27 Feb 2020 09:10:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728621AbgB0JKn (ORCPT ); Thu, 27 Feb 2020 04:10:43 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:22082 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728624AbgB0JKn (ORCPT ); Thu, 27 Feb 2020 04:10:43 -0500 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 01R9597I084018 for ; Thu, 27 Feb 2020 04:10:42 -0500 Received: from e06smtp07.uk.ibm.com (e06smtp07.uk.ibm.com [195.75.94.103]) by mx0a-001b2d01.pphosted.com with ESMTP id 2ydxenx2gc-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 27 Feb 2020 04:10:41 -0500 Received: from localhost by e06smtp07.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) Thu, 27 Feb 2020 09:10:37 -0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06avi18626390.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 01R99dVM50921732 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 27 Feb 2020 09:09:39 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5E813A4040; Thu, 27 Feb 2020 09:10:36 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1BB1CA4051; Thu, 27 Feb 2020 09:10:36 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.152.85.9]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 27 Feb 2020 09:10:36 +0000 (GMT) From: Michael Mueller To: borntraeger@de.ibm.com, frankja@linux.vnet.ibm.com, mimu@linux.ibm.com Cc: kvm@vger.kernel.org, cohuck@redhat.com, david@redhat.com, thuth@redhat.com, linux-s390@vger.kernel.org Subject: [PATCH] KVM: s390: introduce module parameter kvm.use_gisa Date: Thu, 27 Feb 2020 10:10:31 +0100 X-Mailer: git-send-email 2.17.1 X-TM-AS-GCONF: 00 x-cbid: 20022709-0028-0000-0000-000003DE6E4F X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 20022709-0029-0000-0000-000024A38CE3 Message-Id: <20200227091031.102993-1-mimu@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.572 definitions=2020-02-27_02:2020-02-26,2020-02-27 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 lowpriorityscore=0 priorityscore=1501 spamscore=0 suspectscore=0 impostorscore=0 malwarescore=0 phishscore=0 mlxlogscore=999 mlxscore=0 clxscore=1015 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002270074 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org The boolean module parameter "kvm.use_gisa" controls if newly created guests will use the GISA facility if provided by the host system. The default is yes. # cat /sys/module/kvm/parameters/use_gisa Y The parameter can be changed on the fly. # echo N > /sys/module/kvm/parameters/use_gisa Already running guests are not affected by this change. The kvm s390 debug feature shows if a guest is running with GISA. # grep gisa /sys/kernel/debug/s390dbf/kvm-$pid/sprintf 00 01582725059:843303 3 - 08 00000000e119bc01 gisa 0x00000000c9ac2642 initialized 00 01582725059:903840 3 - 11 000000004391ee22 00[0000000000000000-0000000000000000]: AIV gisa format-1 enabled for cpu 000 ... 00 01582725059:916847 3 - 08 0000000094fff572 gisa 0x00000000c9ac2642 cleared In general, that value should not be changed as the GISA facility enhances interruption delivery performance. A reason to switch the GISA facility off might be a performance comparison run or debugging. Signed-off-by: Michael Mueller Reviewed-by: David Hildenbrand Reviewed-by: Cornelia Huck --- arch/s390/kvm/kvm-s390.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index d7ff30e45589..5c2081488024 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -184,6 +184,11 @@ static u8 halt_poll_max_steal = 10; module_param(halt_poll_max_steal, byte, 0644); MODULE_PARM_DESC(halt_poll_max_steal, "Maximum percentage of steal time to allow polling"); +/* if set to true, the GISA will be initialized and used if available */ +static bool use_gisa = true; +module_param(use_gisa, bool, 0644); +MODULE_PARM_DESC(use_gisa, "Use the GISA if the host supports it."); + /* * For now we handle at most 16 double words as this is what the s390 base * kernel handles and stores in the prefix page. If we ever need to go beyond @@ -2504,7 +2509,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) kvm->arch.use_skf = sclp.has_skey; spin_lock_init(&kvm->arch.start_stop_lock); kvm_s390_vsie_init(kvm); - kvm_s390_gisa_init(kvm); + if (use_gisa) + kvm_s390_gisa_init(kvm); KVM_EVENT(3, "vm 0x%pK created by pid %u", kvm, current->pid); return 0;