Re: [Xen-devel] Xen/ARM: Xen queries

[Vijay Kilari <vijay.kilari@xxxxxxxxx>]

On Wed, Jul 16, 2014 at 6:18 PM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> On Wed, 2014-07-16 at 18:15 +0530, Vijay Kilari wrote:
>> On Tue, Jul 15, 2014 at 2:16 PM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> 
>> wrote:
>> > On Tue, 2014-07-15 at 14:14 +0530, Vijay Kilari wrote:
>> >> > BTW, is there any reason to not use copy_{from,to}_guest helpers?
>> >>
>> >>   What Xen has is IPA address of Command Queue. Can copy_{from,to}_guest()
>> >> work with guest IPA address?
>> >
>> > No, they use guest VAs.
>> >
>> > That's not to say that some helpers for copying from guest IPA wouldn't
>> > be a useful addition to Xen though.
>>
>>    I understand that this helper uses map_domain_page() to do so.
>>
>> Query: Is there any existing helpers to convert guest IPA to PA?. I want
>> to access the physical address for a given IPA and program the device with 
>> PA.
>
> You want p2m_lookup() which does IPA->MA translation. Or perhaps it
> would be better/more convenient to get_page_from_gfn() which takes an
> API and returns you the struct page_info * with the reference count
> bumped.

Thank Ian.

I have another query

Scenario:

DOM0 allocates a page for LPI configuration and write start address of
this page (IPA)
is written to register PROP_BASER. which is trapped.
Now DOM0 uses this allocated page to configure LPI's, which is not trapped.

I want to trap on any writes to this page. so that LPI's can be
enabled/disabled.
Is there any API in Xen to unmap Dom's page so that Xen can get trap
on read/writes
to this page ?

Regards
Vijay

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