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 E5FADC433EF for ; Mon, 13 Dec 2021 15:45:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240187AbhLMPpM (ORCPT ); Mon, 13 Dec 2021 10:45:12 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:52212 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S234484AbhLMPpK (ORCPT ); Mon, 13 Dec 2021 10:45:10 -0500 Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 1BDEvQOV017736; Mon, 13 Dec 2021 15:45:10 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=k/TuME2AJGqJsBHTZ2Rb+3YeCtineC0vq6GNn0aKE8Y=; b=TpkVnzz12XYRPqWnvJXYzU805DMGf1Ygk2HCGAVklWhdc5du6+QH0OdGq2GZlE05aB2n MIZRNvn2YLZB5szjvI0KGvGhztK1D0auab85KYR5ni8GVxKotvm2s2s7HfSxyJxZTP71 0j9ktduE6x+eml5jobhIVa3moTmrq+uRFxgilTR/fla9/7xzvTwqiMrbSPHCkQHPNmhf q+xV8RzKnGjg8w2UUwccWIfaamjjS4b721ctiGyYdI83XEAcKOF52SJbQrposqlfo8NY Q0JmLmngRL/s5uOH7kMkqYiGZP2kGV43Uoyz2I6Yg99TkU3+kMuWha2acFm0mIX8jQlV kA== Received: from pps.reinject (localhost [127.0.0.1]) by mx0b-001b2d01.pphosted.com with ESMTP id 3cx8d4h6q4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 13 Dec 2021 15:45:10 +0000 Received: from m0098414.ppops.net (m0098414.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 1BDEwnRw023469; Mon, 13 Dec 2021 15:45:09 GMT Received: from ppma04ams.nl.ibm.com (63.31.33a9.ip4.static.sl-reverse.com [169.51.49.99]) by mx0b-001b2d01.pphosted.com with ESMTP id 3cx8d4h6p9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 13 Dec 2021 15:45:09 +0000 Received: from pps.filterd (ppma04ams.nl.ibm.com [127.0.0.1]) by ppma04ams.nl.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 1BDFiWkW001673; Mon, 13 Dec 2021 15:45:07 GMT Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by ppma04ams.nl.ibm.com with ESMTP id 3cvkma6fet-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 13 Dec 2021 15:45:07 +0000 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 1BDFj3rp44761536 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 13 Dec 2021 15:45:03 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D060511C058; Mon, 13 Dec 2021 15:45:03 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4B14B11C05E; Mon, 13 Dec 2021 15:45:03 +0000 (GMT) Received: from [9.171.24.181] (unknown [9.171.24.181]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 13 Dec 2021 15:45:03 +0000 (GMT) Message-ID: <1b2903fa-7b83-418d-8fa6-9bdf9ad19640@linux.ibm.com> Date: Mon, 13 Dec 2021 16:46:07 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH v5 1/1] s390x: KVM: accept STSI for CPU topology information Content-Language: en-US To: Heiko Carstens Cc: Claudio Imbrenda , kvm@vger.kernel.org, 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, gor@linux.ibm.com References: <20211122131443.66632-1-pmorel@linux.ibm.com> <20211122131443.66632-2-pmorel@linux.ibm.com> <20211209133616.650491fd@p-imbrenda> From: Pierre Morel In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 4D2Z7C5qDideuvog92lsq0xClxYEDLjc X-Proofpoint-ORIG-GUID: OW728l3AKLNzJEcC8le5Ufmenxx2dXzv X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2021-12-13_07,2021-12-13_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 suspectscore=0 spamscore=0 priorityscore=1501 mlxscore=0 mlxlogscore=904 malwarescore=0 bulkscore=0 impostorscore=0 clxscore=1015 phishscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2112130099 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/13/21 16:21, Heiko Carstens wrote: > On Mon, Dec 13, 2021 at 03:26:58PM +0100, Pierre Morel wrote: >>> Why is this assumption necessary? The statement that Linux runs only >>> with horizontal polarization is not true. >>> >> >> Right, I will rephrase this as: >> >> "Polarization change is not taken into account, QEMU intercepts queries for >> polarization change (PTF) and only provides horizontal polarization >> indication to Guest's Linux." >> >> @Heiko, I did not find any usage of the polarization in the kernel other >> than an indication in the sysfs. Is there currently other use of the >> polarization that I did not see? > > You can change polarization by writing to /sys/devices/system/cpu/dispatching. > > Or alternativel use the chcpu tool to change polarization. There is > however no real support for vertical polarization implemented in the > kernel. Therefore changing to vertical polarization is _not_ > recommended, since it will most likely have negative performance > impacts on your Linux system. > However the interface is still there for experimental purposes. > Thanks, so I guess that not reflecting polarization changes to the guest topology will be OK for the moment. Of course, I will change the wrong comment. -- Pierre Morel IBM Lab Boeblingen