[SOLVED] KVM-capable machine?

kikinovak · 02-16-2016, 10:23 AM

Hi,

I'm planning on fiddling with KVM, since up until now, I've only used VirtualBox for virtualization.

I have a book about virtualization using KVM, and in the introductory chapter, it says to first check the processors' capacities. This looks OK on my sandbox machine, an old HP Compaq workstation:

Code:

# egrep '^flags.*(vmx|svm)' /proc/cpuinfo 
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow rep_good nopl extd_apicid pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy 3dnowprefetch lbrv
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow rep_good nopl extd_apicid pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy 3dnowprefetch lbrv

On the other hand, I get a "kvm: disabled by bios" error message on bootup. I took a peek in the BIOS, but there seems to be no virtualization option to enable.

Does that mean that's it? No KVM on this machine?

red_fire · 02-16-2016, 11:16 AM

Hmmm in the BIOS, look for Intel VT-x if your cpu is Intel-based or AMD-V if it's AMD. Enable that and then you have to load kvm-intel or kvm-amd module before using kvm with qemu

kikinovak · 02-16-2016, 11:34 AM

I'll quote myself.

Quote:

Originally Posted by kikinovak

I took a peek in the BIOS, but there seems to be no virtualization option to enable.

ponce · 02-16-2016, 11:50 AM

which model is the workstation? maybe we can find something related about it...

Quote:

Originally Posted by kikinovak

I get a "kvm: disabled by bios" error message on bootup

in which part of the boot you got that message?
do you have it when you do a "modprobe kvm"?

ReaperX7 · 02-16-2016, 12:13 PM

Unless you have virtualization capabilities then you won't have kvm at all. Are you on a Celeron based machine?

kikinovak · 02-16-2016, 12:36 PM

Quote:

Originally Posted by ponce

which model is the workstation? maybe we can find something related about it...

in which part of the boot you got that message?
do you have it when you do a "modprobe kvm"?

It's an HP Compaq DC5850.

philanc · 02-16-2016, 12:37 PM

Quote:

Originally Posted by kikinovak

I'll quote myself.

Quote:

I took a peek in the BIOS, but there seems to be no virtualization option to enable.

Maybe "I took a peek" suggested that you gave a cursory look...

Just in case, in some BIOS, the VT-related options are under "Security" or oddly under "Power".

Beyond that,
- in some older BIOS, VT was just silently blocked by enabling Intel AMT,
- in others, VT was disabled when DEP (Data Execution Prevention - Intel XD or AMD NX) was enabled (*, **)

You may have a BIOS option for one of these and want to try.

(*) This DEP thing is strange because it looks like in more recent machines, on the contrary, it must be enabled, at least for Hyper-V -- see
http://blogs.technet.com/b/iftekhar/...n-hyper-v.aspx

(**) It is strongly suggested in this document and at other places to power off then power on the PC after having changed the DEP setting. From the link above:

Quote:

When you enable hardware assisted virtualization (Intel VT or AMD AMD-V) in the BIOS, you must TURN THE SYSTEM OFF. NOT REBOOT. OFF. If you don’t power cycle the system completely, you will not enable hardware assisted virtualization on the majority of systems in the market.

If nothing works and no BIOS update is available at HP support, you may be out of luck

As a side note, I really would like to understand how some code executed at boot time can permanently lock a function in the CPU. AFAIK, the BIOS is used only at boot and no longer accessed once the kernel starts. So how come the kernel cannot reconfigure the CPU as it sees fit?!?

Anyway, HTH

Phil

philanc · 02-16-2016, 12:50 PM

Quote:

Originally Posted by kikinovak

It's an HP Compaq DC5850.

The BIOS guide for dc5850 [1] says that there is a VT option in Security on some models
[1] http://h20565.www2.hp.com/hpsc/doc/p...r_na-c01361573

Quote:

Virtualization Technology (some models) (enable/disable) Controls the virtualization features of the processor. Changing this setting requires turning the computer off and then back on.

Maybe you don't have the right model

kikinovak · 02-16-2016, 12:55 PM

Quote:

Originally Posted by philanc

Maybe "I took a peek" suggested that you gave a cursory look...

Just in case, in some BIOS, the VT-related options are under "Security" or oddly under "Power".

You're a star. I just found "Virtualization > Enable/Disable", oddly filed under "System Security" (WTF?). It's enabled now, and everything works OK.

Thanks very much, everybody.