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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 4D916C4321D for ; Wed, 22 Aug 2018 20:54:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F01BD208DA for ; Wed, 22 Aug 2018 20:54:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F01BD208DA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727397AbeHWAVD (ORCPT ); Wed, 22 Aug 2018 20:21:03 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:39978 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726789AbeHWAVD (ORCPT ); Wed, 22 Aug 2018 20:21:03 -0400 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w7MKrjM3074591 for ; Wed, 22 Aug 2018 16:54:35 -0400 Received: from e17.ny.us.ibm.com (e17.ny.us.ibm.com [129.33.205.207]) by mx0b-001b2d01.pphosted.com with ESMTP id 2m1c1mqa2k-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 22 Aug 2018 16:54:34 -0400 Received: from localhost by e17.ny.us.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, 22 Aug 2018 16:54:30 -0400 Received: from b01ledav001.gho.pok.ibm.com (b01ledav001.gho.pok.ibm.com [9.57.199.106]) by b01cxnp23032.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w7MKsS5Y16973824 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 22 Aug 2018 20:54:28 GMT Received: from b01ledav001.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 36E9428059; Wed, 22 Aug 2018 16:52:58 -0400 (EDT) Received: from b01ledav001.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 683E22805A; Wed, 22 Aug 2018 16:52:57 -0400 (EDT) Received: from oc8043147753.ibm.com (unknown [9.60.75.213]) by b01ledav001.gho.pok.ibm.com (Postfix) with ESMTP; Wed, 22 Aug 2018 16:52:57 -0400 (EDT) Subject: Re: [PATCH v9 21/22] KVM: s390: CPU model support for AP virtualization To: David Hildenbrand , Tony Krowiak , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: freude@de.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, borntraeger@de.ibm.com, cohuck@redhat.com, kwankhede@nvidia.com, bjsdjshi@linux.vnet.ibm.com, pbonzini@redhat.com, alex.williamson@redhat.com, pmorel@linux.vnet.ibm.com, alifm@linux.vnet.ibm.com, mjrosato@linux.vnet.ibm.com, jjherne@linux.vnet.ibm.com, thuth@redhat.com, pasic@linux.vnet.ibm.com, berrange@redhat.com, fiuczy@linux.vnet.ibm.com, buendgen@de.ibm.com, frankja@linux.ibm.com References: <1534196899-16987-1-git-send-email-akrowiak@linux.vnet.ibm.com> <1534196899-16987-22-git-send-email-akrowiak@linux.vnet.ibm.com> <2c2c4859-ed3e-a492-dd59-78529c7768b2@redhat.com> From: Tony Krowiak Date: Wed, 22 Aug 2018 16:54:26 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: <2c2c4859-ed3e-a492-dd59-78529c7768b2@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 18082220-0040-0000-0000-0000046377F0 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009593; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000266; SDB=6.01077363; UDB=6.00555461; IPR=6.00857339; MB=3.00022873; MTD=3.00000008; XFM=3.00000015; UTC=2018-08-22 20:54:32 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18082220-0041-0000-0000-0000086A8AD3 Message-Id: <8f3f3f41-a052-1975-69e2-49e1a662ecab@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-08-22_11:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1808220207 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/22/2018 07:19 AM, David Hildenbrand wrote: > On 13.08.2018 23:48, Tony Krowiak wrote: >> From: Tony Krowiak >> >> Introduces a new CPU model feature and two CPU model >> facilities to support AP virtualization for KVM guests. >> >> CPU model feature: >> >> The KVM_S390_VM_CPU_FEAT_AP feature indicates that >> AP instructions are available on the guest. This >> feature will be enabled by the kernel only if the AP >> instructions are installed on the linux host. This feature >> must be specifically turned on for the KVM guest from >> userspace to use the VFIO AP device driver for guest >> access to AP devices. >> >> CPU model facilities: >> >> 1. AP Query Configuration Information (QCI) facility is installed. >> >> This is indicated by setting facilities bit 12 for >> the guest. The kernel will not enable this facility >> for the guest if it is not set on the host. >> >> If this facility is not set for the KVM guest, then only >> APQNs with an APQI less than 16 will be used by a Linux >> guest regardless of the matrix configuration for the virtual >> machine. This is a limitation of the Linux AP bus. >> >> 2. AP Facilities Test facility (APFT) is installed. >> >> This is indicated by setting facilities bit 15 for >> the guest. The kernel will not enable this facility for >> the guest if it is not set on the host. >> >> If this facility is not set for the KVM guest, then no >> AP devices will be available to the guest regardless of >> the guest's matrix configuration for the virtual >> machine. This is a limitation of the Linux AP bus. >> >> Signed-off-by: Tony Krowiak >> Reviewed-by: Christian Borntraeger >> Reviewed-by: Halil Pasic >> Tested-by: Michael Mueller >> Tested-by: Farhan Ali >> Signed-off-by: Christian Borntraeger >> --- >> arch/s390/kvm/kvm-s390.c | 5 +++++ >> arch/s390/tools/gen_facilities.c | 2 ++ >> 2 files changed, 7 insertions(+), 0 deletions(-) >> >> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >> index 1e8cb67..d5e04d2 100644 >> --- a/arch/s390/kvm/kvm-s390.c >> +++ b/arch/s390/kvm/kvm-s390.c >> @@ -367,6 +367,11 @@ static void kvm_s390_cpu_feat_init(void) >> >> if (MACHINE_HAS_ESOP) >> allow_cpu_feat(KVM_S390_VM_CPU_FEAT_ESOP); >> + >> + /* Check if AP instructions installed on host */ >> + if (ap_instructions_available()) >> + allow_cpu_feat(KVM_S390_VM_CPU_FEAT_AP); >> + >> /* >> * We need SIE support, ESOP (PROT_READ protection for gmap_shadow), >> * 64bit SCAO (SCA passthrough) and IDTE (for gmap_shadow unshadowing). >> diff --git a/arch/s390/tools/gen_facilities.c b/arch/s390/tools/gen_facilities.c >> index 90a8c9e..a52290b 100644 >> --- a/arch/s390/tools/gen_facilities.c >> +++ b/arch/s390/tools/gen_facilities.c >> @@ -106,6 +106,8 @@ struct facility_def { >> >> .name = "FACILITIES_KVM_CPUMODEL", >> .bits = (int[]){ >> + 12, /* AP Query Configuration Information */ >> + 15, /* AP Facilities Test */ >> -1 /* END */ >> } >> }, >> > I really wonder if we should also export the APXA facility. Given this comment is made within the context of the FACILITIES_KVM_CPUMODEL I might point out that APXA is not indicated by a facilities bit. It is indicated by a bit in the QCI control block returned from the PQAP(QCI) instruction to indicate that APXA is installed on all CPUs. > We can probe and allow that CPU feature. However, we cannot disable it > (as of now). Given this patch series implements passthrough devices, the output of the PQAP(QCI) will always be from a real device - i.e., there will be no way to disable it. > > We have other CPU features where it is the same case (basically all > subfunctions). See kvm_s390_get_processor_subfunc(). We probe them and > export them, but support to disable them has never been implemented. > > On a high level, we could then e.g. deny to start a QEMU guest if APXA > is available but has been disabled. (until we know that disabling it > actually works - if ever). > > This helps to catch nasty migration bugs (e.g. APXA suddenly > disappearing). Although unlikely, definitely possible. Migration of AP devices is not supported by this patch series, so this should not be an issue. > > > Are there any other AP related facilities that the guest can from now on > probe that should also become part of the CPU model? >