21.14. Verifying Virtualization Extensions

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Use this section to determine whether your system has the hardware virtualization extensions. Virtualization extensions (Intel VT-x or AMD-V) are required for full virtualization.
  1. Run the following command to verify the CPU virtualization extensions are available:
    $ grep -E 'svm|vmx' /proc/cpuinfo
  2. Analyze the output.
    • The following output contains a vmx entry indicating an Intel processor with the Intel VT-x extension:
      flags   : fpu tsc msr pae mce cx8 apic mtrr mca cmov pat pse36 clflush
      	dts acpi mmx fxsr sse sse2 ss ht  tm syscall lm constant_tsc pni monitor ds_cpl
      	vmx est tm2 cx16 xtpr lahf_lm
    • The following output contains an svm entry indicating an AMD processor with the AMD-V extensions:
      flags   :  fpu tsc msr pae mce cx8 apic mtrr mca cmov pat pse36 clflush
      	mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt lm 3dnowext 3dnow pni cx16
      	lahf_lm cmp_legacy svm cr8legacy ts fid vid ttp tm stc
    If any output is received, the processor has the hardware virtualization extensions. However in some circumstances manufacturers disable the virtualization extensions in BIOS.
    The "flags:" output content may appear multiple times, once for each hyperthread, core or CPU on the system.
    The virtualization extensions may be disabled in the BIOS. If the extensions do not appear or full virtualization does not work refer to Procedure 21.3, “Enabling virtualization extensions in BIOS”.
  3. Ensure KVM subsystem is loaded

    As an additional check, verify that the kvm modules are loaded in the kernel:
    # lsmod | grep kvm
    If the output includes kvm_intel or kvm_amd then the kvm hardware virtualization modules are loaded and your system meets requirements.


If the libvirt package is installed, the virsh command can output a full list of virtualization system capabilities. Run virsh capabilities as root to receive the complete list.
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