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

[Tony Krowiak <akrowiak@linux.ibm.com>]

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
-- 
2.41.0