Re: nmi is broken?

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2011-05-03 16:37, Avi Kivity wrote:
> On 05/03/2011 05:29 PM, Jan Kiszka wrote:
>> On 2011-05-03 15:31, Avi Kivity wrote:
>>>  On 05/03/2011 01:37 PM, Jan Kiszka wrote:
>>>>>
>>>>>   Yes.  Unfortunately that is very vendor and model specific.  The
>>>>>   architectural PMU is supported, but that is only available on Intel.
>>>>
>>>>  Is it supposed to have any practical value already? I did not yet find a
>>>>  magic -cpu switch to let Linux detect anything, not to speak of perf or
>>>>  watchdog support.
>>>
>>>  On the guest side it is supported for the watchdog
>>>  (arch/x86/kernel/cpu/perfctr-watchdog.c, look for
>>>  X86_FEATURE_ARCH_PERFMON).  It's also mentioned in perf_event_intel.c,
>>>  but I don't know if it will work without the other PMU features being
>>>  present.
>>
>> I've tested with some SUSE 2.6.38 guest kernel, and it complained like
>> this:
>>
>> (-cpu kvm64)
>> Performance Events: unsupported Netburst CPU model 6 no PMU driver, software events only.
>> NMI watchdog disabled (cpu0): hardware events not enabled
>>
> 
> Sorry, I meant to write, but forgot, that on the host side it is 
> completely unsupported.  It shouldn't be too hard to use perf_events to 
> emulate the architectural PMU.  Once we do that we can expose the 
> architectural pmu bit and the guest will use it.

Oh, and I already thought I would have missed some thrilling KVM patches...

Jan

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