[Xen-devel] [BUG] xenstat_vcpu_ns returns invalid value

[Richard Kojedzinszky <richard@xxxxxxxxx>]

Dear Xen Devs,

commit 2529c850ea48f036727ca2f148caed89391311b8 introduces the 
XEN_RUNSTATE_UPDATE marker bit, which is not handled in
vcpu_runstate_get() in xen/common/schedule.c. Relevant code:

    delta = NOW() - runstate->state_entry_time;
    if ( delta > 0 )
        runstate->time[runstate->state] += delta;

If state_entry_time has the bit set, it will be a negative value, so 
delta will be greater than 0, actually the marker bit
will appear in runstate->time too. This causes the MSB bit set in the 
return of xenstat_vcpu_ns(). Is it true, that when reading these values 
through xenstat, the user should take care of this bit, and reread, or 
is it a bug in the relevant code?
I am using xenstat.h interface, where I can only request statistics for 
the whole node. So, basically, walking through all vcpu of all domain, 
and checking that no one
contains this bit seems a bit ugly solution.

Thanks in advance,
Richard Kojedzinszky

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