Re: [Xen-devel] Problems with hyperthreading in Windows HVM

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2012-02-29 at 00:28 +0000, Roderick Colenbrander wrote:
> Hi,
> 
> I have been trying to get Hyperthreading to work in a Windows HVM on
> Xen 4.1.2 as described in 'xmexample.hvm'. I think I have set it up
> correctly, but I can't seem to get it to work. There is not much
> documentation on it and most topics are from years ago.

I don't know the answers to your questions, or whether this particular
type of cpuid modification has ever worked. But might it be that
something on the hypervisor side is also modifying the cpuid results?

I suppose you could start at xen/arch/x86/hvm/emulate.c:hvmemul_cpuid
and trace down to the actual code in question? Looks like hvm_cpuid() is
probably the key function of interest.

Note sure where APIC IDs come from either, xen/arch/x86/hvm/vlapic.c
might be an interesting starting point. Or perhaps this is done by
hvmloader tools/firmware/hvmloader.c?

More questions than answers in the above, sorry about that!

Ian.


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