Re: [kvm-unit-tests] warning: host doesn't support requested feature: CPUID.01H:ECX.vmx [bit 5]

["Radim Krčmář" <rkrcmar@redhat.com>]

2017-08-15 16:39+0800, Li Zhijian:
> Hi guys
> 
> i encountered a problem when i test vmx related cases
> 
> the test log like below
> [adam@skylake kvm-unit-tests]$ ./run_tests.sh
> SKIP vmx_null (0 tests)
> [adam@skylake kvm-unit-tests]$ cat logs/
> SUMMARY       vmx_null.log
> [adam@skylake kvm-unit-tests]$ cat logs/vmx_null.log
> warning: host doesn't support requested feature: CPUID.01H:ECX.vmx [bit 5]
> timeout -k 1s --foreground 90s /usr/bin/qemu-system-x86_64 -nodefaults -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc none -serial stdio -device pci-testdev -machine accel=kvm -kernel x86/vmx.flat -smp 1 -cpu host,+vmx -append null # -initrd /tmp/tmp.wTXf483ild
> enabling apic
> paging enabled
> cr0 = 80010011
> cr3 = 469000
> cr4 = 20
> WARNING: vmx not supported, add '-cpu host'
> SUMMARY: 0 tests
> 
> why the test output this warning, my skylake i5-6500 machine can support vmx feature, and how i can fix it.

The warning means that KVM doesn't allow the guest to see the vmx
feature.  You are most likely without nested vmx, because it is disabled
by default:

  % cat /sys/module/kvm_intel/parameters/nested
  N

In order to turn it on, reload the "kvm_intel" module with "nested=Y"
parameter.

 modprobe -r kvm_intel; modprobe kvm_intel nested=y

If you want to have this automatically, add

  options kvm_intel nested=1

to /etc/modprobe.d/kvm.conf.

> i tried the same test at my another haswell(i7-4790) machine(has the same kernel) doesn't occur this issue.

Not sure why it works on the other machine -- is it a different distro?

Thanks.