vfio: Split VFIO_GROUP_GET_STATUS into a function

This is the last sizable implementation in vfio_group_fops_unl_ioctl(),
move it to a function so vfio_group_fops_unl_ioctl() is emptied out.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/8-v2-0f9e632d54fb+d6-vfio_ioctl_split_jgg@nvidia.comSigned-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/vfio_main.c

@@ -1236,24 +1236,13 @@ static int vfio_group_ioctl_get_device_fd(struct vfio_group *group,
 	return ret;
 }
 
-static long vfio_group_fops_unl_ioctl(struct file *filep,
-				      unsigned int cmd, unsigned long arg)
+static int vfio_group_ioctl_get_status(struct vfio_group *group,
+				       struct vfio_group_status __user *arg)
 {
-	struct vfio_group *group = filep->private_data;
-	void __user *uarg = (void __user *)arg;
-	long ret = -ENOTTY;
-
-	switch (cmd) {
-	case VFIO_GROUP_GET_DEVICE_FD:
-		return vfio_group_ioctl_get_device_fd(group, uarg);
-	case VFIO_GROUP_GET_STATUS:
-	{
+	unsigned long minsz = offsetofend(struct vfio_group_status, flags);
 	struct vfio_group_status status;
-		unsigned long minsz;
 
-		minsz = offsetofend(struct vfio_group_status, flags);
-
-		if (copy_from_user(&status, (void __user *)arg, minsz))
+	if (copy_from_user(&status, arg, minsz))
 		return -EFAULT;
 
 	if (status.argsz < minsz)
@@ -1269,19 +1258,29 @@ static long vfio_group_fops_unl_ioctl(struct file *filep,
 		status.flags |= VFIO_GROUP_FLAGS_VIABLE;
 	up_read(&group->group_rwsem);
 
-		if (copy_to_user((void __user *)arg, &status, minsz))
+	if (copy_to_user(arg, &status, minsz))
 		return -EFAULT;
+	return 0;
+}
 
-		ret = 0;
-		break;
-	}
+static long vfio_group_fops_unl_ioctl(struct file *filep,
+				      unsigned int cmd, unsigned long arg)
+{
+	struct vfio_group *group = filep->private_data;
+	void __user *uarg = (void __user *)arg;
+
+	switch (cmd) {
+	case VFIO_GROUP_GET_DEVICE_FD:
+		return vfio_group_ioctl_get_device_fd(group, uarg);
+	case VFIO_GROUP_GET_STATUS:
+		return vfio_group_ioctl_get_status(group, uarg);
 	case VFIO_GROUP_SET_CONTAINER:
 		return vfio_group_ioctl_set_container(group, uarg);
 	case VFIO_GROUP_UNSET_CONTAINER:
 		return vfio_group_ioctl_unset_container(group);
+	default:
+		return -ENOTTY;
 	}
-
-	return ret;
 }
 
 static int vfio_group_fops_open(struct inode *inode, struct file *filep)