Re: [Qemu-devel] Re: [PATCH 11/11] kvm, x86: broadcast mce depending on the cpu version

[Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>]

(2010/10/15 22:30), Marcelo Tosatti wrote:
> On Fri, Oct 15, 2010 at 10:52:05AM +0900, Hidetoshi Seto wrote:
>> (2010/10/15 10:06), Marcelo Tosatti wrote:
>>> On Thu, Oct 14, 2010 at 05:55:28PM +0900, Jin Dongming wrote:
>>>> There is no reason why SRAO event received by the main thread
>>>> is the only one that being broadcasted.
>>>>
>>>> According to the x86 ASDM vol.3A 15.10.4.1,
>>>> MCE signal is broadcast on processor version 06H_EH or later.
>>>>
>>>> This change is required to handle SRAR in the guest.
>>>>
>>>> Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
>>>> Tested-by: Jin Dongming <jin.dongming@np.css.fujitsu.com>
>>>> ---
>>>>  qemu-kvm.c |   63 +++++++++++++++++++++++++++++------------------------------
>>>>  1 files changed, 31 insertions(+), 32 deletions(-)
>>>
>>> Why is this necessary? _AO SIGBUS should be sent to all vcpu threads and
>>> main thread.
>>
>> Humm? If you are right, vcpu threads will receive same SRAO event twice,
>> one is that received by itself and another is that received by main thread
>> and forwarded by the broadcast.
>>
>> My understanding is (Jin, please correct me if something wrong):
>>  - _AO SIGBUS is sent to main thread only, and then SRAO event is
>>    broadcasted to all vcpu threads.
>>  - _AR SIGBUS is sent to a vcpu thread that tried to touch the
>>    unmapped poisoned page, and SRAR event is posted to the vcpu.
>>
>> One problem here is that SRAR is not broadcasted.
>> The guest might observe the event differently, like "some cpus
>> don't enter machine check."
> 
> Right.
> 
>>> Please separate bug fixes from cleanups. Very nice, thanks. 
>>
>> Maybe this set is considered as 10 cleanups + 1 fix.
>> I think this fix will be complicated one without preceding cleanups.
> 
> Why? All you need is to broadcast from vcpu context.

No, it is not correct. What I really need is reliable QEMU and
maintainable source codes with open community.

Anyway, since I found it could be simpler than what I expected,
I rebased  2 "functional change" pieces in this set to today's
uq/master.

But these are not tested on the tree yet since I could not build
the uq/master due to many warnings on it (even without my fixes).

> Please do a minimal fix separately so it can be backported, and the
> cleanups can be done later once its merged upstream.

When it will be merged?


Thanks,
H.Seto