Re: Design doc of adding ACPI support for arm64 on Xen - version 4

["Roger Pau Monné" <roger.pau@citrix.com>]

El 20/08/15 a les 13.22, Shannon Zhao ha escrit:
> Hi Roger,
> 
> On 2015/8/20 16:20, Roger Pau Monné wrote:
>> El 20/08/15 a les 5.07, Shannon Zhao ha escrit:
>>> On 2015/8/19 23:02, Roger Pau Monné wrote:
>>>> El 19/08/15 a les 14.13, Shannon Zhao ha escrit:
>>>>> XENMAPSPACE "XENMAPSPACE_dev_mmio". The usage of this hypercall
>>>>> parameters:
>>>>> - domid: DOMID_SELF.
>>>>> - space: XENMAPSPACE_dev_mmio.
>>>>> - gpfns: guest physical addresses where the mapping should appear.
>>>>
>>>> This is not complete, you have forgotten to add the idxs field,
>>>
>>> Sorry, I didn't use the idx for the mmio region mapping. What's the idx
>>> useful for here?
>>
>> I've already posted this in the previous version, and you agreed on the
>> interface and the usage of the fields, please see:
>>
>> http://marc.info/?l=xen-devel&m=143986236212359
>>
>> The idxs field is explicitly mentioned there with it's usage.
>>
> 
> Yeah, I said I will add the description of hypercall parameters.
> It seems that we are talking about a different parameter.
> To map the mmio region, I reuse the struct xen_add_to_physmap and there

You should also take into account xen_add_to_physmap_batch (or are you
planning to issue an hypercall for every single MMIO page that you want
to map?), but anyway the idx(s) field is there in both structs.

> is idx not idxs. Everytime Dom0 maps one page and it's mapped 1:1(guest
> physical address is same with real physical hardware address), so it
> only needs to tell the hypervisor the gpfn.

IMHO, I'm not sure why we should restrict this to 1:1 (although I admit
this is going to be the common case). Didn't we are that we are going to
allow non 1:1 mapping of MMIO regions?

If you want you can check in the hypercall handler that idxs[i] ==
gpfns[i], and return -EOPNOTSUPP if they don't match, but I still don't
see why this should be restricted to 1:1 mappings.

Roger.