Laptops and hardware virtualization

[Shankar Viswanathan]

On Sat, Feb 13, 2010 at 8:29 PM, Richard Pieri <richard.pieri-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org> wrote:
> On Feb 13, 2010, at 3:04 PM, Edward Ned Harvey wrote:
>>
>> Just like long mode (aka LM, aka 64bit), the extra functionality for VM or
>> LM inside the CPU costs extra to manufacture or purchase, so I'm going to
>> make a disputable claim that laptop manufacturers won't put VM or LM enabled
>> CPU's into their laptops, unless they're going to build the rest of the
>> components in the laptop to support it too.
>
> Correct me if I'm wrong, but either the CPU supports VT-x/AMD-v or it doesn't. No external support hardware is required.

Yes, that is correct as far as CPU virtualization is concerned.
Support in chipsets etc. is needed only for complete I/O
virtualization (IOMMU support), but that is not commonplace yet. So,
as long as your CPU supports virtualization extensions and it is not
disabled by the BIOS, you should be able to take advantage of the
feature (using compatible VMWare/Virtualbox/Xen/KVM etc.)


>> There are lots of laptops and netbooks out there that do not have these
>> options.
>
> Depends on the CPU.  Atom and Celeron processors don't have the premium features.  Core 2 and Core i series processors have the VT-x extensions; whether or not it is enabled is something else.

Every recent (i.e. mid-2006 or later) AMD processor supports AMD-V
extensions as well.

There are security reasons why certain OEMs disable VT-x/AMD-V in the
BIOS -- search for "Blue Pill" to see the gory details. While this
hole has been demonstrated, I am not aware of any public exploits
(perhaps because it is quite hard to create the necessary conditions).
Still, disabling the extensions if you do not plan to use them is
probably a good idea (my personal opinion, not my employer's).

To answer Jerry's original question, I have looked at several HP
Pavilion 'dv' series laptops (with AMD processors of course ;-) and
they all had AMD-V enabled by default. I remember seeing a Toshiba
Satellite series laptop a couple of years ago that had it disabled,
but it was easy to toggle it back on through the BIOS menu.

-Shankar
(disclaimer: I work for AMD)