Re: VMX ideas

Alexander Graf
2008-10-29T15:11:32Z

On 29.10.2008, at 16:01, Joerg Roedel wrote:

> On Wed, Oct 29, 2008 at 03:52:21PM +0100, Alexander Graf wrote:
>> Hi list,
>>
>> I really do like KVM and would love to make using it a complete no-
>> brainer user experience. For the average user, loading a kernel
>> module
>> (and unloading it) isn't really one of the most common tasks.
>>
>> So I was considering to automatically load kvm-intel and kvm-amd on
>> bootup, when the CPU has a CPUID flag. Unfortunately it doesn't work
>> that easily. VMX enters Root mode, setting a page to use for the
>> VMCS.
>> KVM sets up this page when the kvm-intel module gets loaded. This
>> means, as soon as kvm-intel is modprobe'd, vmware, virtual box,
>> parallels and the like are screwed.
>> From a distribution perspective, this isn't exactly an ideal
>> situation.
>>
>> So I was thinking hard on what to do to circumvent this problem and
>> came up with several approaches:
>
> If you want to allow parallel execution of different hypervisors at
> the
> same time you have a similar problem with SVM because you don't know
> which hypervisor uses which ASID.

Yes, while writing the mail I was thinking to bring that on too, but
figured in the end that the mail's title is "VMX Ideas", so I
didn't ;-).
Of course, if we want to go with 3., we'd need to write a common
framework for the ASIDs in SVM that could handle activation of SVM for
us too.

Right now the situation on VMX is a lot worse than on SVM though, as
loading the module basically blocks every other hypervisor.

Alex