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

[Tony Krowiak]

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@xxxxxxxxxxxxx>
Fixes: f139862b92cf ("s390/vfio-ap: add status attribute to AP queue device's sysfs dir")
Cc: stable@xxxxxxxxxxxxxxx
---
 drivers/s390/crypto/vfio_ap_ops.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 4db538a55192..871c14a6921f 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);
 
@@ -1984,7 +1985,11 @@ static ssize_t status_show(struct device *dev,
 	matrix_mdev = vfio_ap_mdev_for_queue(q);
 
 	if (matrix_mdev) {
-		if (matrix_mdev->kvm)
+		apid = AP_QID_CARD(q->apqn);
+		apqi = AP_QID_QUEUE(q->apqn);
+		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