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 0169EC43381 for ; Tue, 19 Mar 2019 16:48:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CCEE8206B7 for ; Tue, 19 Mar 2019 16:48:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727538AbfCSQsh (ORCPT ); Tue, 19 Mar 2019 12:48:37 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:41250 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726876AbfCSQsg (ORCPT ); Tue, 19 Mar 2019 12:48:36 -0400 Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x2JGmOva139150 for ; Tue, 19 Mar 2019 12:48:35 -0400 Received: from e06smtp07.uk.ibm.com (e06smtp07.uk.ibm.com [195.75.94.103]) by mx0a-001b2d01.pphosted.com with ESMTP id 2rb48xg09r-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 19 Mar 2019 12:48:35 -0400 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) Tue, 19 Mar 2019 16:48:27 -0000 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x2JGmQuV44892402 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 19 Mar 2019 16:48:26 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 17220AE053; Tue, 19 Mar 2019 16:48:26 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B1943AE051; Tue, 19 Mar 2019 16:48:24 +0000 (GMT) Received: from [9.145.41.62] (unknown [9.145.41.62]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 19 Mar 2019 16:48:24 +0000 (GMT) Reply-To: pmorel@linux.ibm.com Subject: Re: [PATCH v5 4/7] s390: ap: setup relation betwen KVM and mediated device To: Halil Pasic Cc: borntraeger@de.ibm.com, alex.williamson@redhat.com, cohuck@redhat.com, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, frankja@linux.ibm.com, akrowiak@linux.ibm.com, david@redhat.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, freude@linux.ibm.com, mimu@linux.ibm.com References: <1552493104-30510-1-git-send-email-pmorel@linux.ibm.com> <1552493104-30510-5-git-send-email-pmorel@linux.ibm.com> <20190315191557.6c8d7668@oc2783563651> <7c199329-0e82-ff61-46b7-78237a0f01ce@linux.ibm.com> <20190319125425.0cf5324e@oc2783563651> <2c459ebe-2b37-72bc-1ede-b196e54dc78d@linux.ibm.com> <20190319162712.37f804f8@oc2783563651> From: Pierre Morel Date: Tue, 19 Mar 2019 17:48:24 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <20190319162712.37f804f8@oc2783563651> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19031916-0028-0000-0000-00000355F212 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19031916-0029-0000-0000-000024149070 Message-Id: <1dd78905-bc87-d47c-6e8a-ba0a2a00102d@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-19_08:,, 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=8.0.1-1810050000 definitions=main-1903190122 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19/03/2019 16:27, Halil Pasic wrote: > On Tue, 19 Mar 2019 15:47:05 +0100 > Pierre Morel wrote: > >>>>>>>        if (matrix_mdev->kvm) >>>>>>>            kvm_arch_crypto_clear_masks(matrix_mdev->kvm); >>>>>> >>>>>> This still conditional? >>>>> >>>>> Yes, nothing to clear if there is no KVM. >>>>> >>>> >>>> Since we have ensured the open only works if there is a KVM at that >>>> point in time, and we have taken a reference to KVM, I would expect >>>> KVM can not go away before we give up our reference. >>> >>> Right. >> >> Right but based on the assumption we do a kvm_get_kvm() during open. >> >> But now we will do it inside the notifier, so the logic is to do a >> kvm_put_kvm in the notifier too. >> This is important because userland will ask us to release the KVM/VFIO >> link through this notifier. >> So I will have to rework this part where KVM==NULL in the notifier too. >> >> Regards, >> Pierre > > I think it can be done both ways. If you ensure KVM != NULL if the open > succeeds and take the reference in the notifier. I suppose if open() > fails release() won't be called. But the logic/code in open() would get > quite ugly because the callback could be called assync so that it > overlaps with the rest of open(). Not necessary, but there is more than just the kvm_get_kvm(). When the user calls KVM_DEV_VFIO_GROUP_DEL he asks to break the link between VFIO and KVM. Currently we just ignore this instead of stopping all activity associated with KVM. But we have more bugs there: We should not support multiple open of the mdev which will overwrite matrix->kvm for the same mdev with a different KVM. I send a bugfix for this. > > Not failing open() in case of no KVM is there yet is in my opinion > cleaner anyway. If we handle correctly the notifiers and the exclusivity, we can do this. I will make this correctly for the next iteration. Regards, Pierre > > Regards, > Halil > -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany