This article explains how to setup your CentOS Linux host so you use it as a Virtualization Host with KVM.
If you have a home server that is powerful enough to host a couple of virtual machines, you don’t have to go all ESXi to make your home server a VM Server. Instead you can use your existing CentOS installation with libvirt and KVM to host virtual machines.
Making sure you can run virtualization you need to verify your CPU support. Use the following command line to find out if your CPU supports virtualization. We can use egrep to go through /proc/cpuinfo to look for the appearance of either vmx (Intel) or svm (AMD).
> egrep '(vmx|svm)' /proc/cpuinfo flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch epb cat_l3 cdp_l3 invpcid_single intel_pt tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm cqm rdt_a rdseed adx smap xsaveopt cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm arat pln pts ...
In the example above you can see one core being reported as eligible. We’re good to go and can install the group package for virtualization:
> sudo yum group install "Virtualization Host"
Making sure a normal user can administrate virtualization a policy needs to be created with polkit. Please make sure to replace andreas with your username:
> sudo groupadd virt > sudo usermod -aG virt andreas > sudo mkdir -p /etc/polkit-1/localauthority/50-local.d/
Now create the file /etc/polkit-1/localauthority/50-local.d/50-org.example.libvirt-access.pkla with the following contents:
[libvirt Admin Access] Identity=unix-group:virt Action=org.libvirt.unix.manage ResultAny=yes ResultInactive=yes ResultActive=yes
That’s it already. On a different host you could install the virt-manager GUI to administrate your VMs from remote. Just use the following command on a third-party CentOS workstation:
> sudo yum install virt-manager
After that start the virtualization manager from the Desktop.