Re: [Qemu-devel] [Qemu-ppc] [PATCH 72/77] ppc: A couple more dummy POWER8 Book4 regs

[Thomas Huth]

On 09.03.2016 21:04, Cédric Le Goater wrote:
> On 03/02/2016 09:30 PM, Thomas Huth wrote:
>> On 11.11.2015 01:28, Benjamin Herrenschmidt wrote:
>>> WORT and PID this time
>>>
...
>> AFAICT all patches where you define new SPRs with spr_register_kvm[_hv]
>> are also important independently of the rest of your patch series -
>> otherwise these registers are currently lost during migration since they
>> are not sync'ed with the KVM part in the kernel right now.
>>
>> So if you've got some spare time, could you maybe extract all those
>> patches that define new SPRs with spr_register_kvm[_hv] and send them as
>> a separate patch series? That could help to fix future migration issues,
>> and also would decrease the size of your really huge "Add native POWER8
>> platform" patch series a little bit!
> 
> I have been maintaining a port of Ben's patchset on the latest qemu for other 
> parts which should come after pnv is merged so I have a framework to test 
> such 
> sub-patchsets. I also have time to work on them but clearly not the expertise
> in all areas !

That would be great if you could take care of this!

> What would be nice is to identify the most obvious ones, non controversial
> that could be merged after a few iterations. I have a vague idea, the ones 
> Reviewed-by David obviously being good candidates, the definition of new SPRs 
> (even the dummy ones ?).

I really like to see the KVM SPRs patches first - since they are fixing
potential problems with migration of the _current_ KVM machines already!
And being bug fixes, maybe these patches could even be included for QEMU
2.6 already? (i.e. before the hard freeze at the end of March)

So my wish-list for a first small patch series looks like this:

5b287e66c7513209  ppc: Add macros to register hypervisor mode SPRs
34f1af75e75e7ba0  ppc: Add dummy CIABR SPR
48adf38e9cab4663  ppc: A couple more dummy POWER8 Book4 regs
730a9b4dc9414818  ppc: Add KVM numbers to some P8 SPRs

There are a couple of other patches touching the SPRs initialization,
but they are not important with regards to migration... so not sure
whether it makes sense to include them now already...

 Thomas