Re: [Xen-devel] [PATCH for-next 9/9] xen: Remove mfn_to_gmfn macro

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 13.03.19 at 19:41, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 13/03/2019 17:42, Julien Grall wrote:
>> On 13/03/2019 17:34, Andrew Cooper wrote:
>>> Given that "having an M2P" is now an x86-specific concept, I think
>>> phasing set_gpfn_from_mfn()'s use out of common code is the way to go.
>>
>> So you never expect other architecture to use the M2P?
> 
> I guess that depends on how likely it is going to be that Xen gains a
> new non-HVM-like virtualisation mode on a new architecture.

Well, not quite. I don't think it would be straightforward to make
x86 select HAVE_M2P only when PV is also enabled. Hence a HVM-
like implementation may still want to maintain M2P. In fact it is
my understanding that 64-bit Arm could easily do (leaving aside
the question of whether the memory needed to build the tables
would be well spent this), but it's prohibitive on 32-bit, and hence
it's easier for the Arm code overall to uniformly resort to
alternative means where such a translation is indeed needed.

Jan



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