How to deallocate extents of physical volume? lvm, encrypted

I just install Debian 8.1. I allocated almost all disk 300 GiB to encrypted partition and a little bit for boot. I want to make smaller 50GiB encrypted physical volume and install different xen OS to the free space. Is it possible to do it without data loss? How? --- System info: /dev/dm-1 ext4 / /dev/sda1 ext2 /boot Files in /dev/mapper: - control - hostname--vg-root - hostname--vg-swap_1 - sda5_crypt --- Added the answer to the first comment: root@X550C:/home/user# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 298.1G 0 disk ├─sda1 8:1 0 243M 0 part /boot ├─sda2 8:2 0 1K 0 part └─sda5 8:5 0 297.9G 0 part └─sda5_crypt 254:0 0 297.9G 0 crypt ├─hostname--vg-root 254:1 0 290.1G 0 lvm / └─hostname--vg-swap_1 254:2 0 7.8G 0 lvm [SWAP] sdb 8:16 0 931.5G 0 disk └─sdb1 8:17 0 931.5G 0 part /media/user/Seagate Backup Plus Drive sr0 11:0 1 1024M 0 rom