Resend due to format issue.

If lspci is not found in your clearlinux sos, you can install the tool by:
$ swupd bundle-add sysadmin-basic

The following instruction will take PCI device 'USB Host 00:15.0' as an example to show the set-up steps.

Hide PCI device in SOS
1) Find out the physical BDF (bus:device.function) for USB Host

$ lspci
<<<<<<<output>>>>>>>
...
00:15.0 USB controller: Intel Corporation Celeron N3350/Pentium N4200/Atom E3900 Series USB xHCI (rev 0b)
...
2) Find out the numeric PCI ID for USB Host

$ lspci -n
<<<<<<<output>>>>>>>
...
00:15.0 0c03: 8086:5aa8 (rev 0b)
...
3) Hide the PCI device in SOS via stub driver

Execute the following commands to hide the PCI device "00:15.0" in SOS

echo "8086 5aa8" > /sys/bus/pci/drivers/pci-stub/new_id
echo "0000:00:15.0" > /sys/bus/pci/devices/0000:00:15.0/driver/unbind
echo "0000:00:15.0" > /sys/bus/pci/drivers/pci-stub/bind
You could double-check whether the PCI device is hidden successfully via the following command.

$ cat /sys/bus/pci/devices/0000:00:15.0/uevent
If it is done successfully, the driver will be shown as 'pci-stub'.

Example:

root@jiechen-xubuntu:~# cat /sys/bus/pci/devices/0000:00:15.0/uevent
DRIVER=pci-stub
PCI_CLASS=C0330
PCI_ID=8086:5AA8
PCI_SUBSYS_ID=0000:0000
PCI_SLOT_NAME=0000:00:15.0
MODALIAS=pci:v00008086d00005AA8sv00000000sd00000000bc0Csc03i30

4) Add parameters in the boot-up command for UOS
Add the following parameters in the boot-up command to pass PCI device 0:15.0 to guest @ virtual PCI 0:7.0

-s 7,passthru,0/15/0
You could change '7' to any other number as long as it's not used by other devices yet.