Re: [Xen-devel] [PATCH v5 00/30] arm64: Dom0 ITS emulation

[Julien Grall <julien.grall@xxxxxxx>]

On 06/04/17 00:18, Andre Przywara wrote:
> Hi,
Hi Andre,

> another round with lots of fixes for the ITS emulation series.
> The access to guest memory has been reworked, we now use a routine to
> copy to and from guest memory to also guarantee atomic access.
> This is courtesy of Vijaya Kumar, from a previous series.
> For a detailed changelog see below.
>
> Open questions:
> - Do we really need the GENMASK_ULL and BIT_ULL version ? This series is
>   really only for ARM64 (which doesn't need those), so we could get rid
>   of this, possibly introduce them later should we *really* need an ARM32
>   version. I think this will be our least problem then.
> - I was thinking about MOVALL and the spec is really confusing here.
>   It needs some discussion whether we need to emulate it or not. However
>   Linux does not use this command, so we might get away with it now.
>   An implementation might be doable along the lines of INVALL.
I would like be ok to skip the implementation for now. However this 
needs to be a TODO.
> - Julien asked for more ITS documentation, which is quite hard to come up
>   with. I will try to explain things in more details tomorrow in commit
>   messages, if there are still things missing.
Yes, writing documentation is quite hard when it is not done at the same 
time as writing the code :). But this is helping the reviewer to 
understand what you wrote. To be clear, I am not asking documenting how 
the hardware ITS ask, although few pointers to the doc is usually 
useful, but having a description in code of the design choice for the vITS.
Anyway, I will try to point where I think the code is not clear and a 
comment is necessary. In the future, I would appreciate if you get use 
to comment your code whilst writing.
Furthermore, I asked to see in the cover letter a list of missing items 
for GICv3 ITS (e.g two-level support, INVALL optimization, MOVALL...). 
But it is still missing. This is a MUST on my side before considering to 
merge ITS into staging.
Cheers,

--
Julien Grall

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