Re: [Xen-devel] [PATCH 0/2 for-4.12] Introduce runstate area registration with phys address

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andrii,

On 3/18/19 1:38 PM, Andrii Anisov wrote:
> On 18.03.19 14:25, Julien Grall wrote:
> > As I already said multiple times before, please try to explain 
> > everything in your first e-mail...
> I know. I'm trying to provide enough info in the cover letter. But it 
> seems I do not succeed.
> Putting all the thoughts might lead into overburdened text. But it looks 
> it should be done. Going to do that next time.
I realize my point is maybe misleading. Overburderned text is indeed not 
very great. Missing something in the cover letter is not entirely a big 
deal. Then the reviewers can ask question for clarification afterwards.
However, when I pointed out that arm32 was left from the text, you 
should have provided more details on why rather than just confirming you 
left it. Maybe I should have been clearer in my review and ask a proper 
question.
> > >   - Smth. similar or different might happen on x86 PV or HVM
> > > Yet, all of them are out of design and are quite unexpected.
> > We *must* protect hypervisor against any guest behavior.
> Totally agree.
>
> > Particularly the unexpected one. If the Android VM hit itself, then I 
> > pretty much don't care assuming the VM was misbehaving. However, I 
> > don't think anyone would be happy if the Android VM is able to take 
> > down the whole platform. At least, I would not want to be the 
> > passenger of that car...
> Neither do I.
>
> > > > You also saw a performance drop when using glmark2 benchmark.
> > > Yes, I did see it with Roger's patch. But with mine - numbers are 
> > > slightly better (~1%) for runstate being mapped. > Also introducing 
> > > more races preventing code will introduce its impact.
> > Please provide the numbers once you fixed the race.
> I'm laying my hands on the tracer now. Want to get numbers from it as wel.
Thank you for doing the benchmark.

Cheers,

--
Julien Grall

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