From patchwork Thu Jul 14 10:18:22 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pierre Morel X-Patchwork-Id: 12917666 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 5F036C43334 for ; Thu, 14 Jul 2022 10:13:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237815AbiGNKN5 (ORCPT ); Thu, 14 Jul 2022 06:13:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52670 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237237AbiGNKNx (ORCPT ); Thu, 14 Jul 2022 06:13:53 -0400 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B43D012D2A; Thu, 14 Jul 2022 03:13:49 -0700 (PDT) Received: from pps.filterd (m0127361.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 26EA9PEa026186; 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Thu, 14 Jul 2022 10:13:42 +0000 (GMT) Received: from li-c6ac47cc-293c-11b2-a85c-d421c8e4747b.ibm.com.com (unknown [9.171.80.107]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 14 Jul 2022 10:13:42 +0000 (GMT) From: Pierre Morel To: kvm@vger.kernel.org Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, cohuck@redhat.com, david@redhat.com, thuth@redhat.com, imbrenda@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, pmorel@linux.ibm.com, wintera@linux.ibm.com, seiden@linux.ibm.com, nrb@linux.ibm.com, scgl@linux.ibm.com Subject: [PATCH v13 0/2] s390x: KVM: CPU Topology Date: Thu, 14 Jul 2022 12:18:22 +0200 Message-Id: <20220714101824.101601-1-pmorel@linux.ibm.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: w6PfKn7TKDsbJeL-TTzi-XbBtmdrn1FK X-Proofpoint-GUID: gu-GcOtgabc0SGR-4KBgLzzZFkFIX67_ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-07-14_08,2022-07-14_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 lowpriorityscore=0 malwarescore=0 bulkscore=0 phishscore=0 adultscore=0 clxscore=1015 mlxlogscore=999 mlxscore=0 spamscore=0 suspectscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2206140000 definitions=main-2207140042 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi all, The series provides: 1- interception of the STSI instruction forwarding the CPU topology 2- interpretation of the PTF instruction 3- a KVM capability for the userland hypervisor to ask KVM to setup PTF interpretation. 4- KVM ioctl to get and set the MTCR bit of the SCA in order to migrate this bit during a migration. 0- Foreword The S390 CPU topology is reported using two instructions: - PTF, to get information if the CPU topology did change since last PTF instruction or a subsystem reset. - STSI, to get the topology information, consisting of the topology of the CPU inside the sockets, of the sockets inside the books etc. The PTF(2) instruction report a change if the STSI(15.1.2) instruction will report a difference with the last STSI(15.1.2) instruction*. With the SIE interpretation, the PTF(2) instruction will report a change to the guest if the host sets the SCA.MTCR bit. *The STSI(15.1.2) instruction reports: - The cores address within a socket - The polarization of the cores - The CPU type of the cores - If the cores are dedicated or not We decided to implement the CPU topology for S390 in several steps: - first we report CPU hotplug In future development we will provide: - modification of the CPU mask inside sockets - handling of shared CPUs - reporting of the CPU Type - reporting of the polarization 1- Interception of STSI To provide Topology information to the guest through the STSI instruction, we forward STSI with Function Code 15 to the userland hypervisor which will take care to provide the right information to the guest. To let the guest use both the PTF instruction to check if a topology change occurred and sthe STSI_15.x.x instruction we add a new KVM capability to enable the topology facility. 2- Interpretation of PTF with FC(2) The PTF instruction reports a topology change if there is any change with a previous STSI(15.1.2) SYSIB. Changes inside a STSI(15.1.2) SYSIB occur if CPU bits are set or clear inside the CPU Topology List Entry CPU mask field, which happens with changes in CPU polarization, dedication, CPU types and adding or removing CPUs in a socket. Considering that the KVM guests currently only supports: - horizontal polarization - type 3 (Linux) CPU And that we decide to support only: - dedicated CPUs on the host - pinned vCPUs on the guest the creation of vCPU will is the only trigger to set the MTCR bit for a guest. The reporting to the guest is done using the Multiprocessor Topology-Change-Report (MTCR) bit of the utility entry of the guest's SCA which will be cleared during the interpretation of PTF. Regards, Pierre Pierre Morel (2): KVM: s390: guest support for topology function KVM: s390: resetting the Topology-Change-Report Documentation/virt/kvm/api.rst | 25 ++++++++++ arch/s390/include/asm/kvm_host.h | 18 +++++-- arch/s390/include/uapi/asm/kvm.h | 1 + arch/s390/kvm/kvm-s390.c | 82 ++++++++++++++++++++++++++++++++ arch/s390/kvm/priv.c | 20 ++++++-- arch/s390/kvm/vsie.c | 8 ++++ include/uapi/linux/kvm.h | 1 + 7 files changed, 148 insertions(+), 7 deletions(-)