You muset setting up for 'virsh console DOMAIN'

add 'console=tty0 console=ttyS0,115200n8'

#kernel /vmlinuz-2.6.18-238.el6 ro root=/dev/***
kernel /vmlinuz-2.6.18-238.el6 ro root=/dev/***   console=tty0 console=ttyS0,115200n8

#add
S0:12345:respawn:/sbin/agetty ttyS0 115200

#Before
GRUB_CMDLINE_LINUX="crashkernel=auto rhgb quiet"

#After
GRUB_CMDLINE_LINUX="crashkernel=auto console=ttyS0,115200n8r"

# grub2-mkconfig -o /boot/grub2/grub.cfg

# vi /etc/securetty
ttyS0       <- add

# vi /etc/grub.conf
kernel /vmlinuz-2.6.18-238.el6 ro root=/dev/***   console=tty0 console=ttyS0,115200n8

# vi /etc/securetty
ttyS0       <- add

# initctl list
serial stop/waiting

# initctl start serial DEV=ttyS0 SPEED=115200
serial (ttyS0) start/running, process 1644 

# vi /etc/securetty
ttyS0

# vi /etc/inittab
S0:12345:respawn:/sbin/agetty ttyS0 115200

# telinit q