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Fri, 28 Aug 2020 08:14:09 +0000 (UTC) Received: from gondolin (ovpn-113-255.ams2.redhat.com [10.36.113.255]) by smtp.corp.redhat.com (Postfix) with ESMTP id 56FCA74E1E; Fri, 28 Aug 2020 08:14:00 +0000 (UTC) Date: Fri, 28 Aug 2020 10:13:57 +0200 From: Cornelia Huck To: Tony Krowiak 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 Subject: Re: [PATCH v10 02/16] s390/vfio-ap: use new AP bus interface to search for queue devices Message-ID: <20200828101357.2ccbc39a.cohuck@redhat.com> In-Reply-To: References: <20200821195616.13554-1-akrowiak@linux.ibm.com> <20200821195616.13554-3-akrowiak@linux.ibm.com> <20200825121334.0ff35d7a.cohuck@redhat.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 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 li= st > >> - * @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 at= tached 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; > >> =20 > >> - 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)) =20 > > I think you should add some explanation to the patch description why > > testing the matrix bitmasks is not needed anymore. =20 >=20 > 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_apq= n() > function, so I replaced it with a call to the function above; however, the > vfio_ap_irq_disable_apqn() function=C2=A0 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. >=20 > 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? >=20 >=20 > > + queue =3D ap_get_qdev(apqn); > > + if (!queue) > > return NULL; > > =20 > > - dev =3D driver_find_device(&matrix_dev->vfio_ap_drv->driver, NULL, > > - &apqn, match_apqn); > > - if (!dev) > > - return NULL; > > - q =3D dev_get_drvdata(dev); > > - q->matrix_mdev =3D matrix_mdev; > > - put_device(dev); > > + q =3D dev_get_drvdata(&queue->ap_dev.device); > > + put_device(&queue->ap_dev.device); > > =20 > > return q; > > } > > (...) > > =20 >=20