Re: [Xen-devel] using mapped vcpu_runstate_info in hvm guest

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 13.11.13 at 14:50, Juergen Gross <juergen.gross@xxxxxxxxxxxxxx> wrote:
> I'm trying to obtain runstate information from the hypervisor in a hvm guest
> via VCPUOP_register_runstate_memory_area. This works, but the information is
> not completely suitable for a hvm guest:
> 
> I can see the time summed up in the different states, but I'm not able to
> deduce the exact time the current vcpu has been running. I see the time when
> the last change to the running state happened (state_entry_time), but this
> time is the hypervisor system time obtained via NOW(). I can't see how to
> map this information to any time information available to the guest (e.g. 
> the tsc value).

__update_vcpu_system_time() specifically considers the case of
vTSC, so I'm not really clear what your problem here is. NOW()
(and hence state_entry_time) are in ns units, and the information
presented in struct vcpu_time_info should be sufficient to do the
necessary mapping (or else I can't see what's different in your
case from the usual PV or PVHVM one).

> A solution would be to modify the runstate information mapped via
> VCPUOP_register_runstate_memory_area: it could contain state_entry_time
> rebased to the guests tsc.

No, that one's defined to be matching up with vcpu_time_info's
system_time.

Jan


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