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 C451BC43381 for ; Thu, 28 Mar 2019 12:53:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9C223204EC for ; Thu, 28 Mar 2019 12:53:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726659AbfC1Mxe (ORCPT ); Thu, 28 Mar 2019 08:53:34 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:48770 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725948AbfC1Mxd (ORCPT ); Thu, 28 Mar 2019 08:53:33 -0400 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x2SCnshW173442 for ; Thu, 28 Mar 2019 08:53:32 -0400 Received: from e06smtp01.uk.ibm.com (e06smtp01.uk.ibm.com [195.75.94.97]) by mx0b-001b2d01.pphosted.com with ESMTP id 2rgwyej2wh-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 28 Mar 2019 08:53:31 -0400 Received: from localhost by e06smtp01.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) Thu, 28 Mar 2019 12:53:28 -0000 Received: from b06wcsmtp001.portsmouth.uk.ibm.com (b06wcsmtp001.portsmouth.uk.ibm.com [9.149.105.160]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x2SCrQpV33095790 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Mar 2019 12:53:26 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 97AEBA405C; Thu, 28 Mar 2019 12:53:26 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2BDEAA4065; Thu, 28 Mar 2019 12:53:26 +0000 (GMT) Received: from [9.152.224.145] (unknown [9.152.224.145]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 28 Mar 2019 12:53:26 +0000 (GMT) Reply-To: pmorel@linux.ibm.com Subject: Re: [PATCH v6 2/7] s390: ap: new vfio_ap_queue structure To: Harald Freudenberger , Tony Krowiak , borntraeger@de.ibm.com Cc: 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, pasic@linux.ibm.com, david@redhat.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, mimu@linux.ibm.com References: <1553265828-27823-1-git-send-email-pmorel@linux.ibm.com> <1553265828-27823-3-git-send-email-pmorel@linux.ibm.com> <169eec34-6397-3150-27df-9985c9e711b8@linux.ibm.com> From: Pierre Morel Date: Thu, 28 Mar 2019 13:53:25 +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: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19032812-4275-0000-0000-000003208FFC X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19032812-4276-0000-0000-0000382F2DA5 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-28_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 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-1903280090 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27/03/2019 12:00, Harald Freudenberger wrote: > On 26.03.19 21:45, Tony Krowiak wrote: >> On 3/22/19 10:43 AM, Pierre Morel wrote: >>> The AP interruptions are assigned on a queue basis and ...snip... >>> +static void vfio_ap_free_queue(int apqn, struct ap_matrix_mdev *matrix_mdev) >>> +{ >>> +    struct vfio_ap_queue *q; >>> + >>> +    q = vfio_ap_get_queue(apqn, &matrix_mdev->qlist); >>> +    if (!q) >>> +        return; >>> +    q->matrix_mdev = NULL; >>> +    vfio_ap_mdev_reset_queue(q); >> >> I'm wondering if it's necessary to reset the queue here. The only time >> a queue is used is when a guest using the mdev device is started. When >> that guest is terminated, the fd for the mdev device is closed and the >> mdev device's release callback is invoked. The release callback resets >> the queues assigned to the mdev device. Is it really necessary to >> reset the queue again when it is unassigned even if there would have >> been no subsequent activity? > When I understand this here right this code is called when a queue goes > away from the guest but is still reserved for use by the vfio dd. So it is > possible to assign the queue now to another guest. But then it makes > sense to clear all the entries in the millicode queue because a pending > reply could be "received" by the wrong guest. > > If this function is just called on remove of a queue device where the > device goes back to the AP bus, a reset is not needed. You are right Harald, the function is called when un-assigning a queue from a mediated device, so it must be reset before to assign it to another. Regards, Pierre -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany