Re: [Xen-devel] [PATCH] x86: don't pass negative time to gtime_to_gtsc() (try 2)

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 10.06.13 at 15:44, George Dunlap <George.Dunlap@xxxxxxxxxxxxx> wrote:
> On Mon, Jun 10, 2013 at 1:15 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>> This mostly reverts commit eb60be3d ("x86: don't pass negative time to
>> gtime_to_gtsc()") and instead corrects __update_vcpu_system_time()'s
>> handling of this_cpu(cpu_time).stime_local_stamp dating back before the
>> start of a HVM guest (which would otherwise lead to a negative value
>> getting passed to gtime_to_gtsc(), causing scale_delta() to produce
>> meaningless output).
>>
>> Flushing the value to zero was wrong, and printing a message for
>> something that can validly happen wasn't very useful either.
> 
> Has this actually caused problems, or is this just a theoretical fix?

The commit this undoes was done because of a crash observed
on the test infrastructure. Recently, the log message that got
added there was found in another test infrastructure log, getting
me to (hopefully) understand what the underlying issue is, leading
to the fix here.

Jan


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