Re: [Xen-devel] runstate_info on hvm domain

[Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxxxxxxx>]

Am Dienstag, 11. November 2008 schrieb Dietmar Hahn:
> Hi list,
>
> I have running a hvm domU with the paravirtualized interface to xen.
> Now I'm looking for an interface to get some informations from the
> scheduler when a vcpu of my domain is running on a physical cpu and how
> long.
>
> I searched through the sources and found VCPUOP_get_runstate_info and
> VCPUOP_register_runstate_memory_area, but these hypercalls are only
> possible on pv domains.
> Are there any similar possibilities for hvm domains?
> Thanks in advance for any hints!
>

To have correct cpu time accounting in our BS2000 hybrid hvm domU we would 
need this feature!

I looked a little bit deeper in the xen source and found that it seems 
possible to use the mentioned features in a hvm domain too.

I added the hypercall HYPERCALL(vcpu_op) to the hvm_hypercall64_table[] and 
hvm_hypercall32_table[] and now I could use the VCPU_OP function 
VCPUOP_get_runstate_info without any problems in my hvm domain, the 
hypervisor updated my runstate_info after registering with 
VCPUOP_register_runstate_memory_area.
As it seems from the source there are no side effects for this 2 functions. 
The memory containing the runstate_info is always in the page table, so 
copy_to_guest() should not fail.

Now my question: Is there a way to get such a feature into the hypervisor, 
should I send a patch, only releasing these both functions?
Thanks.

Dietmar.

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