s390/vfio-ap: Add sysfs attr, ap_config, to export mdev state

Add ap_config sysfs attribute. This will provide the means for
setting or displaying the adapters, domains and control domains assigned
to the vfio-ap mediated device in a single operation. This sysfs
attribute is comprised of three masks: One for adapters, one for domains,
and one for control domains.

This attribute is intended to be used by mdevctl to query a vfio-ap
mediated device's state.

Signed-off-by: "Jason J. Herne" <jjherne@linux.ibm.com>
Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20240415152555.13152-3-jjherne@linux.ibm.com
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

Author: Jason J. Herne

drivers/s390/crypto/vfio_ap_ops.c

@@ -1570,13 +1570,40 @@ static ssize_t guest_matrix_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(guest_matrix);
 
+static ssize_t write_ap_bitmap(unsigned long *bitmap, char *buf, int offset, char sep)
+{
+	return sysfs_emit_at(buf, offset, "0x%016lx%016lx%016lx%016lx%c",
+			 bitmap[0], bitmap[1], bitmap[2], bitmap[3], sep);
+}
+
+static ssize_t ap_config_show(struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
+	int idx = 0;
+
+	idx += write_ap_bitmap(matrix_mdev->matrix.apm, buf, idx, ',');
+	idx += write_ap_bitmap(matrix_mdev->matrix.aqm, buf, idx, ',');
+	idx += write_ap_bitmap(matrix_mdev->matrix.adm, buf, idx, '\n');
+
+	return idx;
+}
+
+static ssize_t ap_config_store(struct device *dev, struct device_attribute *attr,
+			       const char *buf, size_t count)
+{
+	return count;
+}
+static DEVICE_ATTR_RW(ap_config);
+
 static struct attribute *vfio_ap_mdev_attrs[] = {
 	&dev_attr_assign_adapter.attr,
 	&dev_attr_unassign_adapter.attr,
 	&dev_attr_assign_domain.attr,
 	&dev_attr_unassign_domain.attr,
 	&dev_attr_assign_control_domain.attr,
 	&dev_attr_unassign_control_domain.attr,
+	&dev_attr_ap_config.attr,
 	&dev_attr_control_domains.attr,
 	&dev_attr_matrix.attr,
 	&dev_attr_guest_matrix.attr,