Re: [Qemu-ppc] [PATCH v5 08/36] ppc/xive: introduce a simplified XIVE presenter

[Benjamin Herrenschmidt]

On Thu, 2018-11-29 at 11:47 +1100, David Gibson wrote:
> 
> 1) read/write accessors which take a word number
> 
> 2) A "get" accessor which copies the whole structure, but "write"
> accessor which takes a word number.  The asymmetry is a bit ugly, but
> it's the non-atomic writeback of the whole structure which I'm most
> uncomfortable with.

It shouldn't be a big deal though, there are HW facilities to access
the structures "atomically" anyway, due to the caching done by the
XIVE.

> 3) A map/unmap interface which gives you / releases a pointer to the
> "live" structure.  For powernv that would become
> address_space_map()/unmap().  For PAPR it would just be reutn pointer
> / no-op.