Re: [PATCH v9 02/15] s390/vfio-ap: use new AP bus interface to search for queue devices

[Tony Krowiak]

On 7/24/20 4:38 AM, Pierre Morel wrote:
> On 2020-07-20 17:03, Tony Krowiak wrote:
> > This patch refactor's the vfio_ap device driver to use the AP bus's
> > ap_get_qdev() function to retrieve the vfio_ap_queue struct containing
> > information about a queue that is bound to the vfio_ap device driver.
> > The bus's ap_get_qdev() function retrieves the queue device from a
> > hashtable keyed by APQN. This is much more efficient than looping over
> > the list of devices attached to the AP bus by several orders of
> > magnitude.
>
> The patch does much more than modifying this line. ;)

Yes it does, I'll be sure to include the additional details.

> > Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > ---
> > Â drivers/s390/crypto/vfio_ap_drv.cÂÂÂÂ | 27 ++-------
> > Â drivers/s390/crypto/vfio_ap_ops.cÂÂÂÂ | 86 +++++++++++++++------------
> > Â drivers/s390/crypto/vfio_ap_private.h |Â 8 ++-
> > Â 3 files changed, 59 insertions(+), 62 deletions(-)
> >
> > diff --git a/drivers/s390/crypto/vfio_ap_drv.c 
> > b/drivers/s390/crypto/vfio_ap_drv.c
> > index f4ceb380dd61..24cdef60039a 100644
> > --- a/drivers/s390/crypto/vfio_ap_drv.c
> > +++ b/drivers/s390/crypto/vfio_ap_drv.c
> > @@ -53,15 +53,9 @@ MODULE_DEVICE_TABLE(vfio_ap, ap_queue_ids);
> > ÂÂ */
> > Â static int vfio_ap_queue_dev_probe(struct ap_device *apdev)
> > Â {
> > -ÂÂÂ struct vfio_ap_queue *q;
> > -
> > -ÂÂÂ q = kzalloc(sizeof(*q), GFP_KERNEL);
> > -ÂÂÂ if (!q)
> > -ÂÂÂÂÂÂÂ return -ENOMEM;
> > -ÂÂÂ dev_set_drvdata(&apdev->device, q);
> > -ÂÂÂ q->apqn = to_ap_queue(&apdev->device)->qid;
> > -ÂÂÂ q->saved_isc = VFIO_AP_ISC_INVALID;
> > -ÂÂÂ return 0;
> > +ÂÂÂ struct ap_queue *queue = to_ap_queue(&apdev->device);
> > +
> > +ÂÂÂ return vfio_ap_mdev_probe_queue(queue);
> > Â }
>
> You should explain the reason why this function is modified.
>
> > Â Â /**
> > @@ -72,18 +66,9 @@ static int vfio_ap_queue_dev_probe(struct 
> > ap_device *apdev)
> > ÂÂ */
> > Â static void vfio_ap_queue_dev_remove(struct ap_device *apdev)
> > Â {
> > -ÂÂÂ struct vfio_ap_queue *q;
> > -ÂÂÂ int apid, apqi;
> > -
> > -ÂÂÂ mutex_lock(&matrix_dev->lock);
> > -ÂÂÂ q = dev_get_drvdata(&apdev->device);
> > -ÂÂÂ dev_set_drvdata(&apdev->device, NULL);
> > -ÂÂÂ apid = AP_QID_CARD(q->apqn);
> > -ÂÂÂ apqi = AP_QID_QUEUE(q->apqn);
> > -ÂÂÂ vfio_ap_mdev_reset_queue(apid, apqi, 1);
> > -ÂÂÂ vfio_ap_irq_disable(q);
> > -ÂÂÂ kfree(q);
> > -ÂÂÂ mutex_unlock(&matrix_dev->lock);
> > +ÂÂÂ struct ap_queue *queue = to_ap_queue(&apdev->device);
> > +
> > +ÂÂÂ vfio_ap_mdev_remove_queue(queue);
> > Â }
>
> ... and this one?
>
> > Â Â static void vfio_ap_matrix_dev_release(struct device *dev)
> > diff --git a/drivers/s390/crypto/vfio_ap_ops.c 
> > b/drivers/s390/crypto/vfio_ap_ops.c
> > index e0bde8518745..ad3925f04f61 100644
> > --- a/drivers/s390/crypto/vfio_ap_ops.c
> > +++ b/drivers/s390/crypto/vfio_ap_ops.c
> > @@ -26,43 +26,26 @@
> > Â Â static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev);
> > Â -static int match_apqn(struct device *dev, const void *data)
> > -{
> > -ÂÂÂ struct vfio_ap_queue *q = dev_get_drvdata(dev);
> > -
> > -ÂÂÂ return (q->apqn == *(int *)(data)) ? 1 : 0;
> > -}
> > -
> > Â /**
> > - * 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.
> > ÂÂ * @apqn: The queue APQN
> > ÂÂ *
> > - * 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.
> > ÂÂ *
> > - * Returns the pointer to the associated vfio_ap_queue
> > + * Returns the pointer to the vfio_ap_queue with the specified APQN, 
> > or NULL.
> > ÂÂ */
> > -static struct vfio_ap_queue *vfio_ap_get_queue(
> > -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ struct ap_matrix_mdev *matrix_mdev,
> > -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ int apqn)
> > +static struct vfio_ap_queue *vfio_ap_get_queue(unsigned long apqn)
> > Â {
> > +ÂÂÂ struct ap_queue *queue;
> > ÂÂÂÂÂ struct vfio_ap_queue *q;
> > -ÂÂÂ struct device *dev;
> > Â -ÂÂÂ if (!test_bit_inv(AP_QID_CARD(apqn), matrix_mdev->matrix.apm))
> > -ÂÂÂÂÂÂÂ return NULL;
> > -ÂÂÂ if (!test_bit_inv(AP_QID_QUEUE(apqn), matrix_mdev->matrix.aqm))
> > +ÂÂÂ queue = ap_get_qdev(apqn);
> > +ÂÂÂ if (!queue)
> > ÂÂÂÂÂÂÂÂÂ return NULL;
> > Â -ÂÂÂ dev = driver_find_device(&matrix_dev->vfio_ap_drv->driver, NULL,
> > -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ &apqn, match_apqn);
> > -ÂÂÂ if (!dev)
> > -ÂÂÂÂÂÂÂ return NULL;
> > -ÂÂÂ q = dev_get_drvdata(dev);
> > -ÂÂÂ q->matrix_mdev = matrix_mdev;
> > -ÂÂÂ put_device(dev);
> > +ÂÂÂ q = dev_get_drvdata(&queue->ap_dev.device);
> > +ÂÂÂ put_device(&queue->ap_dev.device);
> > Â ÂÂÂÂÂ return q;
> > Â }
>
> this function changed a lot too, you should explain the goal in the 
> patch comment.
>
> ...snip...
>
> Regards,
> Pierre