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

[Ian Campbell <ian.campbell@citrix.com>]

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)

Ian.

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