Re: [PATCH 0/9] Add support for nested SVM (kernel) v3

[Joerg Roedel <joerg.roedel@amd.com>]

On Fri, Sep 19, 2008 at 04:36:00PM +0200, Joerg Roedel wrote:
> On Wed, Sep 17, 2008 at 03:41:17PM +0200, Alexander Graf wrote:
> > To be usable, this patchset requires the two simple changes in the userspace
> > part, that I sent to the list with the first version.
> > 
> > Thanks for reviewing!
> 
> Ok, with the patch attached applied on-top of your patches I got a
> recent KVM running inside KVM. And it doesn't feel very slow :-)
> I will do some benchmarks in the next days to get real numbers. The
> patches look good so far.
> But I think for now we should disable the feature by default and allow
> enabling it from userspace until we are sure we don't introduce any
> security hole and don't destroy migration with it. We can add a
> -nested-virt parameter to qemu to enable it for the guest then.
> Another thing missing is the SVM feature CPUID function. It is used to
> find out the number of ASIDs available. But this is a minor issue as
> long as we only run KVM inside KVM.

Ok, further testing showed two issues so far:

- guest timing seems not to work, the printk timing information in ubuntu
  stay at 0.00000 all the time
- smp for the second level guest does not work, it crashes also the
  first level guest

Joerg

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