Re: VMX ideas

Alexander Graf
2008-10-29T17:16:07Z

On 29.10.2008, at 16:45, Anthony Liguori wrote:

> Gerd Hoffmann wrote:
>> Alexander Graf wrote:
>>
>>> So I was thinking hard on what to do to circumvent this problem
>>> and came
>>> up with several approaches:
>>>
>>
>>
>>> 3. Create a root mode bloat framework
>>>
>>
>> 4. Enter vmx root mode when the first user opens /dev/kvm and leave
>> it
>> when nobody uses it any more?
>>
>> Also note that there has been some discussion on lkml to move vmx-
>> root
>> on/off out of the kvm module into the kernel. There are a few places
>> where it would be useful for the kernel to handle that without the
>> kvm
>> module being involved, crashdump kexec for example. With that and
>> some
>> locking in place (so only one can use vmx-root at a time) and
>> hypervisors being friendly to each other and grab vmx-root only when
>> they have a guest to run we should be set?
>>
>
> There was some patch that went into KVM that would indicate in CPU
> state that VT root mode was enabled so that VMware could detect that
> someone else was using VT. Look through the archives.

The only patch I've found is that KVM sets CR4.VMXE to 0 on unload
(hardware_disable). This doesn't really help, as my goal is to have
the module loaded at boot-time.

Alex