Re: [Xen-devel] Xen HVM regression on certain Intel CPUs

["H. Peter Anvin" <hpa@xxxxxxxxx>]

On 03/27/2013 09:24 AM, Stefan Bader wrote:
>> 
>> When you say Xen HVM, am I correct in assuming that neither CPUID
>> nor CR4 operations in the main kernel are run through
>> paravirt_ops?
> 
> Not paravirt ops likely but the hypervisor traps access. At least
> cpuid from within a hvm guest I expect to be filtered. So when
> checking things I went to bare-metal.
> 
> Will fetch more info and get back.
> 

Hypervisor traps is one thing... they should be consistent no matter
where in the code they happen... unless they are broken.

Try this CPUID program.  This uses the kernel /dev interface which may
be somewhat suboptimal in case CPUID in userspace actually differs,
but it would be interesting to know what it outputs.

        -hpa

Attachment: cpuid.c
Description: Text Data

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