Re: [Hackathon] Linux session notes

[David Vrabel <david.vrabel@citrix.com>]

On 04/06/14 12:37, Stefano Stabellini wrote:
> On Wed, 4 Jun 2014, David Vrabel wrote:
>> On 04/06/14 12:11, Stefano Stabellini wrote:
>>> On Mon, 2 Jun 2014, David Vrabel wrote:
>>>> - Fixing m2p override.  Mapping the same MFN (by two grant refs or the
>>>>   same) two or more times means get_user_pages() cannot find the right
>>>>   page() since m2p override is many-to-one.
>>>
>>> Did anybody proposed any ways to fix this issue?
>>> We have the same problem on ARM in p2m.c and I cannot see any way to
>>> solve the issue without slowing down the mfn to pfn conversion too much.
>>
>> I was planning to add an array of pages to the vma and use this in
>> get_user_pages() (instead of the page table walk).
> 
> That is a bit too concise.
> Does that mean you are not going to fix the mfn to pfn conversion
> problem and instead change the common code implementation of
> get_user_pages?

Yes.  It's impossible to fix mfn_to_pfn() for foreign MFNs.

David