s390: vfio-ap: sysfs interfaces to configure domains

Introduces two new sysfs attributes for the VFIO mediated
matrix device for assigning AP domains to and unassigning
AP domains from a mediated matrix device. The IDs of the
AP domains assigned to the mediated matrix device will be
stored in an AP queue mask (AQM).

The bits in the AQM, from most significant to least
significant bit, correspond to AP queue index (APQI) 0 to
255 (note that an APQI is synonymous with with a domain ID).
On some systems, the maximum allowable domain number may be
less than 255 - depending upon the host's AP configuration -
and assignment may be rejected if the input domain ID exceeds
the limit.

When a domain is assigned, the bit corresponding to the APQI
will be set in the AQM. Likewise, when a domain is unassigned,
the bit corresponding to the APQI will be cleared from the AQM.

In order to successfully assign a domain, the APQNs derived from
the domain ID being assigned and the adapter numbers of all
adapters previously assigned:

1. Must be bound to the vfio_ap device driver.

2. Must not be assigned to any other mediated matrix device.

If there are no adapters assigned to the mdev, then there must
be an AP queue bound to the vfio_ap device driver with an
APQN containing the domain ID (i.e., APQI), otherwise all
adapters subsequently assigned will fail because there will be no
AP queues bound with an APQN containing the APQI.

Assigning or un-assigning an AP domain will also be rejected if
a guest using the mediated matrix device is running.

The relevant sysfs structures are:

/sys/devices/vfio_ap/matrix/
...... [mdev_supported_types]
......... [vfio_ap-passthrough]
............ [devices]
...............[$uuid]
.................. assign_domain
.................. unassign_domain

To assign a domain to the $uuid mediated matrix device,
write the domain's ID to the assign_domain file. To
unassign a domain, write the domain's ID to the
unassign_domain file. The ID is specified using
conventional semantics: If it begins with 0x, the number
will be parsed as a hexadecimal (case insensitive) number;
if it begins with 0, it will be parsed as an octal number;
otherwise, it will be parsed as a decimal number.

For example, to assign domain 173 (0xad) to the mediated matrix
device $uuid:

	echo 173 > assign_domain

	or

	echo 0255 > assign_domain

	or

	echo 0xad > assign_domain

To unassign domain 173 (0xad):

	echo 173 > unassign_domain

	or

	echo 0255 > unassign_domain

	or

	echo 0xad > unassign_domain

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Tested-by: Michael Mueller <mimu@linux.ibm.com>
Tested-by: Farhan Ali <alifm@linux.ibm.com>
Tested-by: Pierre Morel <pmorel@linux.ibm.com>
Message-Id: <20180925231641.4954-8-akrowiak@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

drivers/s390/crypto/vfio_ap_ops.c

@@ -382,10 +382,146 @@ static ssize_t unassign_adapter_store(struct device *dev,
 }
 DEVICE_ATTR_WO(unassign_adapter);
 
+static int
+vfio_ap_mdev_verify_queues_reserved_for_apqi(struct ap_matrix_mdev *matrix_mdev,
+					     unsigned long apqi)
+{
+	int ret;
+	unsigned long apid;
+	unsigned long nbits = matrix_mdev->matrix.apm_max + 1;
+
+	if (find_first_bit_inv(matrix_mdev->matrix.apm, nbits) >= nbits)
+		return vfio_ap_verify_queue_reserved(NULL, &apqi);
+
+	for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, nbits) {
+		ret = vfio_ap_verify_queue_reserved(&apid, &apqi);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * assign_domain_store
+ *
+ * @dev:	the matrix device
+ * @attr:	the mediated matrix device's assign_domain attribute
+ * @buf:	a buffer containing the AP queue index (APQI) of the domain to
+ *		be assigned
+ * @count:	the number of bytes in @buf
+ *
+ * Parses the APQI from @buf and sets the corresponding bit in the mediated
+ * matrix device's AQM.
+ *
+ * Returns the number of bytes processed if the APQI is valid; otherwise returns
+ * one of the following errors:
+ *
+ *	1. -EINVAL
+ *	   The APQI is not a valid number
+ *
+ *	2. -ENODEV
+ *	   The APQI exceeds the maximum value configured for the system
+ *
+ *	3. -EADDRNOTAVAIL
+ *	   An APQN derived from the cross product of the APQI being assigned
+ *	   and the APIDs previously assigned is not bound to the vfio_ap device
+ *	   driver; or, if no APIDs have yet been assigned, the APQI is not
+ *	   contained in an APQN bound to the vfio_ap device driver.
+ *
+ *	4. -EADDRINUSE
+ *	   An APQN derived from the cross product of the APQI being assigned
+ *	   and the APIDs previously assigned is being used by another mediated
+ *	   matrix device
+ */
+static ssize_t assign_domain_store(struct device *dev,
+				   struct device_attribute *attr,
+				   const char *buf, size_t count)
+{
+	int ret;
+	unsigned long apqi;
+	struct mdev_device *mdev = mdev_from_dev(dev);
+	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
+	unsigned long max_apqi = matrix_mdev->matrix.aqm_max;
+
+	ret = kstrtoul(buf, 0, &apqi);
+	if (ret)
+		return ret;
+	if (apqi > max_apqi)
+		return -ENODEV;
+
+	mutex_lock(&matrix_dev->lock);
+
+	ret = vfio_ap_mdev_verify_queues_reserved_for_apqi(matrix_mdev, apqi);
+	if (ret)
+		goto done;
+
+	set_bit_inv(apqi, matrix_mdev->matrix.aqm);
+
+	ret = vfio_ap_mdev_verify_no_sharing(matrix_mdev);
+	if (ret)
+		goto share_err;
+
+	ret = count;
+	goto done;
+
+share_err:
+	clear_bit_inv(apqi, matrix_mdev->matrix.aqm);
+done:
+	mutex_unlock(&matrix_dev->lock);
+
+	return ret;
+}
+DEVICE_ATTR_WO(assign_domain);
+
+
+/**
+ * unassign_domain_store
+ *
+ * @dev:	the matrix device
+ * @attr:	the mediated matrix device's unassign_domain attribute
+ * @buf:	a buffer containing the AP queue index (APQI) of the domain to
+ *		be unassigned
+ * @count:	the number of bytes in @buf
+ *
+ * Parses the APQI from @buf and clears the corresponding bit in the
+ * mediated matrix device's AQM.
+ *
+ * Returns the number of bytes processed if the APQI is valid; otherwise,
+ * returns one of the following errors:
+ *	-EINVAL if the APQI is not a number
+ *	-ENODEV if the APQI exceeds the maximum value configured for the system
+ */
+static ssize_t unassign_domain_store(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t count)
+{
+	int ret;
+	unsigned long apqi;
+	struct mdev_device *mdev = mdev_from_dev(dev);
+	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
+
+	ret = kstrtoul(buf, 0, &apqi);
+	if (ret)
+		return ret;
+
+	if (apqi > matrix_mdev->matrix.aqm_max)
+		return -ENODEV;
+
+	mutex_lock(&matrix_dev->lock);
+	clear_bit_inv((unsigned long)apqi, matrix_mdev->matrix.aqm);
+	mutex_unlock(&matrix_dev->lock);
+
+	return count;
+}
+DEVICE_ATTR_WO(unassign_domain);
+
 static struct attribute *vfio_ap_mdev_attrs[] = {
 	&dev_attr_assign_adapter.attr,
 	&dev_attr_unassign_adapter.attr,
-	NULL
+	&dev_attr_assign_domain.attr,
+	&dev_attr_unassign_domain.attr,
+	NULL,
 };
 
 static struct attribute_group vfio_ap_mdev_attr_group = {