Re: [PATCH v2] s390/vfio-ap: fix sysfs status attribute for AP queue devices

Tony Krowiak
2023-11-08T20:21:27Z

Christian,
Can this be pushed with the Acks by Halil and Harald?

On 11/8/23 15:11, Tony Krowiak wrote:
> The 'status' attribute for AP queue devices bound to the vfio_ap device
> driver displays incorrect status when the mediated device is attached to a
> guest, but the queue device is not passed through. In the current
> implementation, the status displayed is 'in_use' which is not correct; it
> should be 'assigned'. This can happen if one of the queue devices
> associated with a given adapter is not bound to the vfio_ap device driver.
> For example:
>
> Queues listed in /sys/bus/ap/drivers/vfio_ap:
> 14.0005
> 14.0006
> 14.000d
> 16.0006
> 16.000d
>
> Queues listed in /sys/devices/vfio_ap/matrix/$UUID/matrix
> 14.0005
> 14.0006
> 14.000d
> 16.0005
> 16.0006
> 16.000d
>
> Queues listed in /sys/devices/vfio_ap/matrix/$UUID/guest_matrix
> 14.0005
> 14.0006
> 14.000d
>
> The reason no queues for adapter 0x16 are listed in the guest_matrix is
> because queue 16.0005 is not bound to the vfio_ap device driver, so no
> queue associated with the adapter is passed through to the guest;
> therefore, each queue device for adapter 0x16 should display 'assigned'
> instead of 'in_use', because those queues are not in use by a guest, but
> only assigned to the mediated device.
>
> Let's check the AP configuration for the guest to determine whether a
> queue device is passed through before displaying a status of 'in_use'.
>
> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
> Acked-by: Halil Pasic <pasic@linux.ibm.com>
> Acked-by: Harald Freudenberger <freude@linux.ibm.com>
> ---
> drivers/s390/crypto/vfio_ap_ops.c | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index 4db538a55192..6e0a79086656 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -1976,6 +1976,7 @@ static ssize_t status_show(struct device *dev,
> {
> ssize_t nchars = 0;
> struct vfio_ap_queue *q;
> + unsigned long apid, apqi;
> struct ap_matrix_mdev *matrix_mdev;
> struct ap_device *apdev = to_ap_dev(dev);
>
> @@ -1983,8 +1984,21 @@ static ssize_t status_show(struct device *dev,
> q = dev_get_drvdata(&apdev->device);
> matrix_mdev = vfio_ap_mdev_for_queue(q);
>
> + /* If the queue is assigned to the matrix mediated device, then
> + * determine whether it is passed through to a guest; otherwise,
> + * indicate that it is unassigned.
> + */
> if (matrix_mdev) {
> - if (matrix_mdev->kvm)
> + apid = AP_QID_CARD(q->apqn);
> + apqi = AP_QID_QUEUE(q->apqn);
> + /*
> + * If the queue is passed through to the guest, then indicate
> + * that it is in use; otherwise, indicate that it is
> + * merely assigned to a matrix mediated device.
> + */
> + if (matrix_mdev->kvm &&
> + test_bit_inv(apid, matrix_mdev->shadow_apcb.apm) &&
> + test_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm))
> nchars = scnprintf(buf, PAGE_SIZE, "%s\n",
> AP_QUEUE_IN_USE);
> else