Re: nmi is broken?

[OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>]

Avi Kivity <avi@redhat.com> writes:

> On 05/01/2011 04:45 AM, OGAWA Hirofumi wrote:
>> >
>> >  Hm.., if smp was enabled, what configuration model is used by kvm? I
>> >  think this configuration model can't work on smp.
>>
>> As far as I can see, kvm is not configured (from MADT and some of
>> behaviors) like you said.
>
> We may well have an error there; and our NMI-from-PIT emulation bypasses 
> all the wiring I described, so we may be emulating a configuration that 
> can't possibly exist on hardware.
>
>> So, I think there are some solutions, a) current behavior is right (I
>> don't know why it's right though), b) fix the behavior of IO-APIC and
>> MADT like you said, then linux can detect it, c) change the model to
>> like mpspec figure 5-2, d) other.
>>
>> My suggestion is c) if there is no good d). Because current behavior
>> looks like almost c), and non-legacy chipsets are using c) model as far
>> as I know.
>
> You're probably right.  However we can't just change it, we need to make 
> it an option, keeping the current configuration as the default.  This is 
> so that live migration can work, and because 5-2 requires a new 
> kernel/user interface, to set IMCR.E0.
>
> Looking at figures 3-3 and 3-4 of the mpspec, the current model supports 
> 3-3 but not 3-4.  Do we report that IMCR exists in the mptables?

I don't think we have to implement IMCR, because it seems to be an
optional. In fact, physical hardwares which I have don't report IMCR in
mptables. (I don't see the benefit to implement it on recent chipsets
even if it's possible. The virtual wire mode seems to be enough.)

I don't know about live migration of kvm. If we said the wiring is like
figure 5-2, what is required for the live migration? It was required
only if IMCR was required?

Thanks.
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>