Fedora Core 6 Xen Virtualization Guide
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Fully-virtualized guests (HVM/Intel-VT/AMD-V)

To run fully virtualized guests, host CPU support is needed. This is typically referred to as Intel VT, or AMD-V. Xen uses a generic 'HVM' layer to support both CPU vendors. To check for Intel VT support look for the 'vmx' flag, or for AMD-V support check for 'svm' flag:

• ....For Intel....
  # grep vmx /proc/cpuinfo 
  flags           : fpu tsc msr pae mce cx8 apic mtrr mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm constant_tsc pni monitor ds_cpl vmx est tm2 cx16 xtpr lahf_lm
  
  ....For AMD....
  # grep svm /proc/cpuinfo
  flags           : fpu tsc msr pae mce cx8 apic mtrr mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm cr8_legacy
  

If you have the 'svm' or 'vmx' flags, then your CPU is capable of fully-virt, however, a large number of machines disable this in the BIOS as shipped from the factory. Thus to see if it is enabled we need to check for the 'hvm-???' flags in the hypervisor capability set:

# cat /sys/hypervisor/properties/capabilities 
xen-3.0-x86_64 hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64

If the above shows one or more 'hvm-???' flags then everything is working normally. If no hvm is shown, then reboot, go into the BIOS & look for a setting related to 'Virtualization' - every BIOS manufacturer calls the setting by a different name. If you are really very unlucky, it is possible the BIOS does not have a virtualization option. In this case the only otion is to bug your hardware vendor for an updated BIOS

Fedora Core 6 Xen Virtualization Guide
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