how to find out if running inside KVM guest

Solution 1:

Grep dmesg, there should be at least one line containing kvm. On my machines:

[    0.000000] kvm-clock: cpu 0, msr 0:5dd801, boot clock
[    0.000000] kvm-clock: cpu 0, msr 0:1023801, primary cpu clock

Alternativly check /proc/cpuinfo, it contains a line:

model name : QEMU Virtual CPU version 0.9.1

But, the problem is: You can't be sure you are an KVM guest (on top of QEMU) or only a QEMU-Guest.

Solution 2:

You can check if imvirt or virt-what which are available for several Linux distros, including Ubuntu, can help you.

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Solution 3:

Current versions of lscpu also show if a hypervisor is detected:

# lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                2
On-line CPU(s) list:   0,1
Thread(s) per core:    1
Core(s) per socket:    1
Socket(s):             2
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 23
Model name:            Intel Core 2 Duo P9xxx (Penryn Class Core 2)
Stepping:              3
CPU MHz:               2659.936
BogoMIPS:              5319.87
Hypervisor vendor:     KVM
Virtualization type:   full
...

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Solution 4:

systemd-detect-virt

returns on this Ubuntu 18.04 KVM setup:

kvm

and on my host:

none

See also: https://unix.stackexchange.com/questions/89714/easy-way-to-determine-virtualization-technology

Tested on an Ubuntu 18.04 host.