From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:60622 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726321AbgH1PKt (ORCPT ); Fri, 28 Aug 2020 11:10:49 -0400 Subject: Re: [PATCH v10 02/16] s390/vfio-ap: use new AP bus interface to search for queue devices References: <20200821195616.13554-1-akrowiak@linux.ibm.com> <20200821195616.13554-3-akrowiak@linux.ibm.com> <20200825121334.0ff35d7a.cohuck@redhat.com> <20200828101357.2ccbc39a.cohuck@redhat.com> From: Tony Krowiak Message-ID: Date: Fri, 28 Aug 2020 11:10:40 -0400 MIME-Version: 1.0 In-Reply-To: <20200828101357.2ccbc39a.cohuck@redhat.com> Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-s390-owner@vger.kernel.org List-ID: To: Cornelia Huck Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, freude@linux.ibm.com, borntraeger@de.ibm.com, mjrosato@linux.ibm.com, pasic@linux.ibm.com, alex.williamson@redhat.com, kwankhede@nvidia.com, fiuczy@linux.ibm.com, frankja@linux.ibm.com, david@redhat.com, imbrenda@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, kernel test robot On 8/28/20 4:13 AM, Cornelia Huck wrote: > On Thu, 27 Aug 2020 10:24:07 -0400 > Tony Krowiak wrote: > >> On 8/25/20 6:13 AM, Cornelia Huck wrote: >>> On Fri, 21 Aug 2020 15:56:02 -0400 >>> Tony Krowiak wrote: >>>> /** >>>> - * vfio_ap_get_queue: Retrieve a queue with a specific APQN from a list >>>> - * @matrix_mdev: the associated mediated matrix >>>> + * vfio_ap_get_queue: Retrieve a queue with a specific APQN. >>>> * @apqn: The queue APQN >>>> * >>>> - * Retrieve a queue with a specific APQN from the list of the >>>> - * devices of the vfio_ap_drv. >>>> - * Verify that the APID and the APQI are set in the matrix. >>>> + * Retrieve a queue with a specific APQN from the AP queue devices attached to >>>> + * the AP bus. >>>> * >>>> - * Returns the pointer to the associated vfio_ap_queue >>>> + * Returns the pointer to the vfio_ap_queue with the specified APQN, or NULL. >>>> */ >>>> -static struct vfio_ap_queue *vfio_ap_get_queue( >>>> - struct ap_matrix_mdev *matrix_mdev, >>>> - int apqn) >>>> +static struct vfio_ap_queue *vfio_ap_get_queue(unsigned long apqn) >>>> { >>>> + struct ap_queue *queue; >>>> struct vfio_ap_queue *q; >>>> - struct device *dev; >>>> >>>> - if (!test_bit_inv(AP_QID_CARD(apqn), matrix_mdev->matrix.apm)) >>>> - return NULL; >>>> - if (!test_bit_inv(AP_QID_QUEUE(apqn), matrix_mdev->matrix.aqm)) >>> I think you should add some explanation to the patch description why >>> testing the matrix bitmasks is not needed anymore. >> As a result of this comment, I took a closer look at the code to >> determine the reason for eliminating the matrix_mdev >> parameter. The reason is because the code below (i.e., find the device >> and get the driver data) was also repeated in the vfio_ap_irq_disable_apqn() >> function, so I replaced it with a call to the function above; however, the >> vfio_ap_irq_disable_apqn() function  does not have a reference to the >> matrix_mdev, so I eliminated the matrix_mdev parameter. Note that the >> vfio_ap_irq_disable_apqn() is called for each APQN assigned to a matrix >> mdev, so there is no need to test the bitmasks there. >> >> The other place from which the function above is called is >> the handle_pqap() function which does have a reference to the >> matrix_mdev. In order to ensure the integrity of the instruction >> being intercepted - i.e., PQAP(AQIC) enable/disable IRQ for aN >> AP queue - the testing of the matrix bitmasks probably ought to >> be performed, so it will be done there instead of in the >> vfio_ap_get_queue() function above. > Should you add a comment that vfio_ap_get_queue() assumes that the > caller makes sure that this is only called for APQNs that are assigned > to a matrix? I suppose it wouldn't hurt. > >> >>> + queue = ap_get_qdev(apqn); >>> + if (!queue) >>> return NULL; >>> >>> - dev = driver_find_device(&matrix_dev->vfio_ap_drv->driver, NULL, >>> - &apqn, match_apqn); >>> - if (!dev) >>> - return NULL; >>> - q = dev_get_drvdata(dev); >>> - q->matrix_mdev = matrix_mdev; >>> - put_device(dev); >>> + q = dev_get_drvdata(&queue->ap_dev.device); >>> + put_device(&queue->ap_dev.device); >>> >>> return q; >>> } >>> (...) >>>