s390: vfio-ap: implement VFIO_DEVICE_GET_INFO ioctl

Adds support for the VFIO_DEVICE_GET_INFO ioctl to the VFIO
AP Matrix device driver. This is a minimal implementation,
as vfio-ap does not use I/O regions.
Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Acked-by: Halil Pasic <pasic@linux.ibm.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: <20180925231641.4954-13-akrowiak@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

drivers/s390/crypto/vfio_ap_ops.c

@@ -855,6 +855,43 @@ static void vfio_ap_mdev_release(struct mdev_device *mdev)
 	module_put(THIS_MODULE);
 }
 
+static int vfio_ap_mdev_get_device_info(unsigned long arg)
+{
+	unsigned long minsz;
+	struct vfio_device_info info;
+
+	minsz = offsetofend(struct vfio_device_info, num_irqs);
+
+	if (copy_from_user(&info, (void __user *)arg, minsz))
+		return -EFAULT;
+
+	if (info.argsz < minsz)
+		return -EINVAL;
+
+	info.flags = VFIO_DEVICE_FLAGS_AP;
+	info.num_regions = 0;
+	info.num_irqs = 0;
+
+	return copy_to_user((void __user *)arg, &info, minsz);
+}
+
+static ssize_t vfio_ap_mdev_ioctl(struct mdev_device *mdev,
+				    unsigned int cmd, unsigned long arg)
+{
+	int ret;
+
+	switch (cmd) {
+	case VFIO_DEVICE_GET_INFO:
+		ret = vfio_ap_mdev_get_device_info(arg);
+		break;
+	default:
+		ret = -EOPNOTSUPP;
+		break;
+	}
+
+	return ret;
+}
+
 static const struct mdev_parent_ops vfio_ap_matrix_ops = {
 	.owner			= THIS_MODULE,
 	.supported_type_groups	= vfio_ap_mdev_type_groups,
@@ -863,6 +900,7 @@ static const struct mdev_parent_ops vfio_ap_matrix_ops = {
 	.remove			= vfio_ap_mdev_remove,
 	.open			= vfio_ap_mdev_open,
 	.release		= vfio_ap_mdev_release,
+	.ioctl			= vfio_ap_mdev_ioctl,
 };
 
 int vfio_ap_mdev_register(void)

include/uapi/linux/vfio.h

@@ -200,6 +200,7 @@ struct vfio_device_info {
 #define VFIO_DEVICE_FLAGS_PLATFORM (1 << 2)	/* vfio-platform device */
 #define VFIO_DEVICE_FLAGS_AMBA  (1 << 3)	/* vfio-amba device */
 #define VFIO_DEVICE_FLAGS_CCW	(1 << 4)	/* vfio-ccw device */
+#define VFIO_DEVICE_FLAGS_AP	(1 << 5)	/* vfio-ap device */
 	__u32	num_regions;	/* Max region index + 1 */
 	__u32	num_irqs;	/* Max IRQ index + 1 */
 };