Re: [Xen-devel] [PATCH] ARM: Support for guest-request vm-events

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

On 01/28/2016 02:45 PM, Ian Campbell wrote:
> On Thu, 2016-01-28 at 14:36 +0200, CORNELIU ZUZU wrote:
>> On 1/28/2016 1:23 PM, Ian Campbell wrote:
>>> On Thu, 2016-01-28 at 13:17 +0200, Corneliu ZUZU wrote:
>>>> This patch implements ARM support for guest-request vm-events.
>>>> The code has been ported from x86 side w/ minor adjustments.
>>> I've not looked at the patch yet, but if it only involves minor
>>> adjustments
>>> from the x86 side can some amount of it not be refactored into common
>>> code?
>>>
>>> Ian.
>>>
>>
>> At a first glance it seems to me that parts of monitor vm-events code 
>> could be moved to common.
>> But it also seems that it would require a bit of effort and I'm not sure 
>> yet if the end result
>> won't actually complicate implementation of monitor vm-events for other 
>> architectures in the future.
>> Some of the monitor vm-events implemented are strictly architecture 
>> specific,
>> e.g. VM_EVENT_REASON_MOV_TO_MSR will always be an x86-only vm-event, unless
>> it is somehow generalized (maybe somehow merged w/ 
>> VM_EVENT_REASON_WRITE_CTRLREG?).
>> But *most* of them indeed don't directly have this kind of specificity, 
>> so it would make sense to make
>> most of the code common, if possible.
> 
> That the sort of thing we would usually handle by having the common code
> call into a arch_foo() to decode any non-common options.
> 
>> To me personally this seems like a good idea and I'd be willing to give 
>> it a try, but as I said,
>> it might require some other changes of the code, including x86 changes.
>> I was about to release another patch after this one to implement 
>> control-register writes
>> vm-events for ARM, but I anticipate that doing this move first will 
>> actually benefit my effort in that
>> direction as well (I think the patch code will get to be cleaner).
>>
>> So, shall I try it?
> 
> From my POV as an ARM maintainer I think this is the way to go. I've also
> copied the VM EVENT maintainers in case they object for some reason.
> 
> I'd recommend always CCing Razvan and Tamas on this series, and considering
> adding any new ARM files to the entry in MAINTAINERS (assuming they don't
> object of course)

No objection from me on either factoring out the common code (where, and
if possible) or adding the new files to MAINTAINERS.


Thanks,
Razvan

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