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 026BDC43381 for ; Thu, 14 Feb 2019 18:31:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C52972075B for ; Thu, 14 Feb 2019 18:31:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390687AbfBNSbK (ORCPT ); Thu, 14 Feb 2019 13:31:10 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:35664 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725781AbfBNSbK (ORCPT ); Thu, 14 Feb 2019 13:31:10 -0500 Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x1EIU15k061572 for ; Thu, 14 Feb 2019 13:31:08 -0500 Received: from e11.ny.us.ibm.com (e11.ny.us.ibm.com [129.33.205.201]) by mx0b-001b2d01.pphosted.com with ESMTP id 2qnc2kxjuh-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 14 Feb 2019 13:31:08 -0500 Received: from localhost by e11.ny.us.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, 14 Feb 2019 18:31:04 -0000 Received: from b01ledav002.gho.pok.ibm.com (b01ledav002.gho.pok.ibm.com [9.57.199.107]) by b01cxnp23033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x1EIV0bg14942284 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 14 Feb 2019 18:31:00 GMT Received: from b01ledav002.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C204912405E; Thu, 14 Feb 2019 18:31:00 +0000 (GMT) Received: from b01ledav002.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0D4A012405B; Thu, 14 Feb 2019 18:31:00 +0000 (GMT) Received: from [9.80.213.209] (unknown [9.80.213.209]) by b01ledav002.gho.pok.ibm.com (Postfix) with ESMTP; Thu, 14 Feb 2019 18:30:59 +0000 (GMT) Subject: Re: [PATCH v3 1/9] s390: vfio_ap: link the vfio_ap devices to the vfio_ap bus subsystem To: pmorel@linux.ibm.com, Cornelia Huck Cc: borntraeger@de.ibm.com, alex.williamson@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, freude@linux.ibm.com, mimu@linux.ibm.com References: <1550152269-6317-1-git-send-email-pmorel@linux.ibm.com> <1550152269-6317-2-git-send-email-pmorel@linux.ibm.com> <20190214155441.087d2a68.cohuck@redhat.com> <9403117a-04a6-8f69-2a61-f96d35a59555@linux.ibm.com> <20190214175730.4ab609ae.cohuck@redhat.com> <9200b1f8-874f-ffa7-bef0-19ca570d7ac1@linux.ibm.com> From: Tony Krowiak Date: Thu, 14 Feb 2019 13:30:59 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <9200b1f8-874f-ffa7-bef0-19ca570d7ac1@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19021418-2213-0000-0000-000003514171 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010596; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000280; SDB=6.01161042; UDB=6.00606024; IPR=6.00941598; MB=3.00025584; MTD=3.00000008; XFM=3.00000015; UTC=2019-02-14 18:31:06 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19021418-2214-0000-0000-00005D5B4233 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-02-14_09:,, 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-1902140125 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/14/19 12:36 PM, Pierre Morel wrote: > On 14/02/2019 17:57, Cornelia Huck wrote: >> On Thu, 14 Feb 2019 16:47:30 +0100 Pierre Morel >> wrote: >> >>> On 14/02/2019 15:54, Cornelia Huck wrote: >>>> On Thu, 14 Feb 2019 14:51:01 +0100 Pierre Morel >>>> wrote: >> >>>>> +++ b/drivers/s390/crypto/vfio_ap_drv.c @@ -24,8 +24,9 @@ >>>>> MODULE_LICENSE("GPL v2"); >>>>> >>>>> static struct ap_driver vfio_ap_drv; >>>>> >>>>> -static struct device_type vfio_ap_dev_type = { -    .name = >>>>> VFIO_AP_DEV_TYPE_NAME, +struct matrix_driver { +    struct >>>>> device_driver drv; +    int device_count; >>>> >>>> This counter basically ensures that at most one device may bind >>>> with this driver... you'd still have that device on the bus, >>>> though. >>> >>> yes, this is what is wanted: this driver can only support one >>> device. May be another matrix driver can support one or more other >>> devices. >>> >>> I should update comment message my be. >>> >>>> >>>>> }; >>>>> >>>>> struct ap_matrix_dev *matrix_dev; >>> >>>>> >>>>> -    matrix_dev->device.type = &vfio_ap_dev_type; >>>>> dev_set_name(&matrix_dev->device, "%s", VFIO_AP_DEV_NAME); >>>>> matrix_dev->device.parent = root_device; + >>>>> matrix_dev->device.bus = &matrix_bus; matrix_dev->device.release = >>>>> vfio_ap_matrix_dev_release; - >>>>> matrix_dev->device.driver = &vfio_ap_drv.driver; + >>>>> matrix_dev->vfio_ap_drv = &vfio_ap_drv; >>>> >>>> Can't you get that structure through matrix_dev->device.driver >>>> instead when you need it in the function below? >>> >>> Not anymore. We have two different drivers and devices matrix_drv >>> <-> matrix_dev and vfio_ap_drv <-> ap_devices >>> >>> The driver behind the matrix_dev->dev->driver is matrix_drv what is >>> needed here is vfio_ap_drv. >> >> Wait, we had tacked a driver for ap devices unto a matrix device, >> which is not on the ap bus? It's really a bit more complicated than that. Without going into a lengthy description of the history of AP passthrough support, suffice it to say that we needed a device to serve as the parent of each mediated device used to configure a matrix of AP adapter IDs and domain indexes identifying the devices to which a guest would be granted access. The AP devices themselves are attached to the AP bus, but the matrix device is an artificial (virtual?) device whose sole purpose in life is to serve as an anchor for the mediated devices whose sysfs interfaces are created and managed by the vfio_ap device driver. The matrix device itself is created by the vfio_ap device driver - when it is initialized - for that purpose. In hindsight, maybe there was a better way to implement this, but neither this patch nor this discussion belongs in this series. It distracts from discussion of interrupt support which is the sole purpose of the patch series. > > ...yes -( > >> Maybe that's what trips libudev? > >> (And reading further in the current code, it seems we clear that >> structure _after_ the matrix device had been setup, so how can that >> even work? Where am I confused?) > > On device_register there were no bus, so the core just do not look for a > driver and this field was nor tested nor overwritten. > >> >>> >>>> >>>>> >>>>> ret = device_register(&matrix_dev->device); if (ret) goto >>>>> matrix_reg_err; >>>>> >>>>> +    ret = driver_register(&matrix_driver.drv); +    if (ret) >>>>> +        goto >>>>> matrix_drv_err; + >>>> >>>> As you already have several structures that can be registered >>>> exactly once (the root device, the bus, the driver, ...), you can >>>> already be sure that there's only one device on the bus, can't >>>> you? >>> >>> hum, no I don't think so, no device can register before this module >>> is loaded, but what does prevent a device to register later from >>> another module? >> >> Not unless you export the interface, I guess. >> > > :) definitively right > thanks, this will simplify the code in the next version. > I will take the patch away from this series to get the way to stable as > Christian requested. > > Regards, > Pierre >