On Thu, 22 Oct 2020 13:11:57 -0400
Tony Krowiak <akrowiak@xxxxxxxxxxxxx> wrote:
> This patch refactors 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.
>
> Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
Reviewed-by: Halil Pasic <pasic@xxxxxxxxxxxxx>
> ---
> drivers/s390/crypto/vfio_ap_ops.c | 35 +++++++++++++------------------
> 1 file changed, 14 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index c471832f0a30..049b97d7444c 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -26,43 +26,36 @@
>
> static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev);
>
> -static int match_apqn(struct device *dev, const void *data)
> -{
> - struct vfio_ap_queue *q = dev_get_drvdata(dev);
> -
> - return (q->apqn == *(int *)(data)) ? 1 : 0;
> -}
> -
> /**
> - * vfio_ap_get_queue: Retrieve a queue with a specific APQN from a list
> + * vfio_ap_get_queue: Retrieve a queue with a specific APQN.
> * @matrix_mdev: the associated mediated matrix
> * @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)
> + unsigned long apqn)
> {
> - struct vfio_ap_queue *q;
> - struct device *dev;
> + struct ap_queue *queue;
> + struct vfio_ap_queue *q = NULL;
>
> 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))
> return NULL;
>
> - dev = driver_find_device(&matrix_dev->vfio_ap_drv->driver, NULL,
> - &apqn, match_apqn);
> - if (!dev)
> + queue = ap_get_qdev(apqn);
> + if (!queue)
> return NULL;
> - q = dev_get_drvdata(dev);
> - q->matrix_mdev = matrix_mdev;
> - put_device(dev);
> +
> + if (queue->ap_dev.device.driver == &matrix_dev->vfio_ap_drv->driver)
> + q = dev_get_drvdata(&queue->ap_dev.device);
> +
Needs to be called with the vfio_ap lock held, right? Otherwise the queue could
get unbound while we are working with it as a vfio_ap_queue... Noting
new, but might we worth documenting.
> + put_device(&queue->ap_dev.device);
>
> return q;
> }
