Messages in this thread | | | From | Tony Krowiak <> | Subject | Re: [PATCH v10 02/16] s390/vfio-ap: use new AP bus interface to search for queue devices | Date | Thu, 27 Aug 2020 10:24:07 -0400 |
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On 8/25/20 6:13 AM, Cornelia Huck wrote: > On Fri, 21 Aug 2020 15:56:02 -0400 > Tony Krowiak<akrowiak@linux.ibm.com> wrote: > >> This patch refactor's the vfio_ap device driver to use the AP bus's > s/refactor's/refactors/
Of course, what was I thinking?:)
>> 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@linux.ibm.com> >> Reported-by: kernel test robot<lkp@intel.com> >> --- >> drivers/s390/crypto/vfio_ap_drv.c | 27 ++------- >> drivers/s390/crypto/vfio_ap_ops.c | 86 +++++++++++++++------------ >> drivers/s390/crypto/vfio_ap_private.h | 8 ++- >> 3 files changed, 59 insertions(+), 62 deletions(-) >> > (...) > >> 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 @@ >> >> 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 >> - * @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.
> + 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; > } > (...) >
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