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

[ Upstream commit a0d8f4eeb7c4ffaee21702bcc91a09b3988c5b7a ]

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>
Link: https://lore.kernel.org/r/20231108201135.351419-1-akrowiak@linux.ibm.com
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 88f41f9..d6ea2fd 100644 (file)
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -2044,6 +2044,7 @@ 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);
 
@@ -2051,8 +2052,21 @@ 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