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 4D9DFC4321D for ; Thu, 23 Aug 2018 10:01:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E1C8D214FF for ; Thu, 23 Aug 2018 10:01:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E1C8D214FF 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 S1730035AbeHWN34 (ORCPT ); Thu, 23 Aug 2018 09:29:56 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:59124 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727231AbeHWN34 (ORCPT ); Thu, 23 Aug 2018 09:29:56 -0400 Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w7N9wr2b087002 for ; Thu, 23 Aug 2018 06:00:59 -0400 Received: from e06smtp04.uk.ibm.com (e06smtp04.uk.ibm.com [195.75.94.100]) by mx0a-001b2d01.pphosted.com with ESMTP id 2m1suf2jyr-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 23 Aug 2018 06:00:58 -0400 Received: from localhost by e06smtp04.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 23 Aug 2018 11:00:54 +0100 Received: from b06cxnps4074.portsmouth.uk.ibm.com (9.149.109.196) by e06smtp04.uk.ibm.com (192.168.101.134) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 23 Aug 2018 11:00:50 +0100 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w7NA0mAH38469726 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 23 Aug 2018 10:00:48 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 52293A405F; Thu, 23 Aug 2018 13:00:48 +0100 (BST) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 59433A405B; Thu, 23 Aug 2018 13:00:46 +0100 (BST) Received: from oc0155643701.ibm.com (unknown [9.145.172.109]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 23 Aug 2018 13:00:46 +0100 (BST) Subject: Re: [PATCH v9 21/22] KVM: s390: CPU model support for AP virtualization To: David Hildenbrand , Tony Krowiak , 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> <95e6ee74-69aa-9805-3233-b9ec81fce516@redhat.com> <7e7a35f5-d1eb-7719-c5e8-57d6f19db675@linux.ibm.com> From: Halil Pasic Date: Thu, 23 Aug 2018 12:00:46 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 18082310-0016-0000-0000-000001FAA347 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18082310-0017-0000-0000-00003250FD90 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-08-23_05:,, 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-1808230107 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/23/2018 09:44 AM, David Hildenbrand wrote: > On 22.08.2018 22:16, Tony Krowiak wrote: >> On 08/22/2018 07:24 AM, David Hildenbrand wrote: >>> On 22.08.2018 13:19, 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. >>>> >>>> We can probe and allow that CPU feature. However, we cannot disable it >>>> (as of now). >>>> >>>> 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. >>>> >>>> >>>> Are there any other AP related facilities that the guest can from now on >>>> probe that should also become part of the CPU model? >>>> >>> To be more precise, shouldn't PQAP(QCI) be handled just like other >>> subfunctions? (I remember it should) >> >> When you suggest PQAP(QCI) be handled like other subfunctions, are you >> suggesting that there should be a field in struct kvm_s390_vm_cpu_subfunc >> with a bit indicating the QCI subfunction is available? The availability >> of the QCI subfunction of the PQAP instruction is determined by facilities >> bit 12. Is it not enough to export facilities bit 12? > > The feature block (128 bit) from PQAP(QCI) should be passed through a > subfunction block to QEMU. > I'm confused, which 128 bit? > So it is about passing e.g. APXA availability, not QCI itself. (as you > correctly said, that is stfl 12) >