Re: [Xen-devel] [PATCH for-next 8/9] xen: Introduce HAS_M2P config and use to protect mfn_to_gmfn call

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 13.03.19 at 18:30, <julien.grall@xxxxxxx> wrote:
> On 13/03/2019 15:20, Jan Beulich wrote:
>>>>> On 18.02.19 at 12:35, <julien.grall@xxxxxxx> wrote:
>>> --- a/xen/common/domctl.c
>>> +++ b/xen/common/domctl.c
>>> @@ -205,7 +205,7 @@ void getdomaininfo(struct domain *d, struct 
> xen_domctl_getdomaininfo *info)
>>>       info->outstanding_pages = d->outstanding_pages;
>>>       info->shr_pages         = atomic_read(&d->shr_pages);
>>>       info->paged_pages       = atomic_read(&d->paged_pages);
>>> -    info->shared_info_frame = mfn_to_gmfn(d, virt_to_mfn(d->shared_info));
>>> +    info->shared_info_frame = gfn_x(domain_shared_info_gfn(d));
>> 
>> I think this change wants to be accompanied by a warning attached
>> to the field declaration in the public header.
> 
> Make sense.
> 
>> 
>> But I'd also like to have the tool stack maintainers' view on making
>> this field effectively unusable for Arm.
> 
> The value in shared_info_frame was plain wrong since the creation of Xen Arm. 
> So 
> this is just making the error more obvious. I don't expect any user of it on 
> Arm.

Well, my request for tool stack maintainer input wasn't to put under
question that the field can't currently be used sensibly on Arm.
Instead I'm meaning to know whether it can be sensibly expected
for the tool stack to want to use the field uniformly, in which case
rather than making it more obviously not work it should be fixed
instead.

Jan



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