Re: [hybrid]: code review for function mapping pfn to foreign mfn

[Tim Deegan <tim@xen.org>]

At 11:18 -0700 on 26 Apr (1335439128), Mukesh Rathor wrote:
> On Thu, 26 Apr 2012 10:08:47 +0100
> Tim Deegan <tim@xen.org> wrote:
> 
> > At 16:06 -0700 on 24 Apr (1335283603), Mukesh Rathor wrote:
> > > On Tue, 24 Apr 2012 10:36:26 +0100
> > > Tim Deegan <tim@xen.org> wrote:
> > > 
> > > > At 18:37 -0700 on 23 Apr (1335206229), Mukesh Rathor wrote:
> > > > > On Thu, 19 Apr 2012 15:15:27 +0100
> > > > > Tim Deegan <tim@xen.org> wrote:
> > > 
> > > >you still have this mapping.  You should take a PGT_writeable_page
> > > >typecount, too, if the foreign domain isn't in paging_mode_external
> > > 
> > > Ok, I've it as:
> > >     if (paging_mode_external(fdom)) {
> > >         if (get_page_from_pagenr(mfn, fdom) == 0)
> > > 	    failed = 1;
> > >     } else {
> > >         if (get_page_and_type_from_pagenr(mfn, PGT_writable_page,
> > > fdom,0,0)) failed = 1;
> > >     }
> > > 
> > > But then later fails when it tries to pin the page,
> > > MMUEXT_PIN_L4_TABLE, from the lib at:
> > 
> > What's trying to pin an l4 table?  I thought your hybrid dom0 didn't
> > use the PV MMU.
> > 
> > Tim.
> 
> Right, hybrid doesn't use PV mmu. 
> Here, xl/xc is building a pv guest while running on *hybrid* dom0. 

Oh, I see.  This is the domU's L4.  In that case I suspect that what's
missing is the translation from GFNs to MFNs in the domU. 

To do that, we may finally have to reintroduce the dreaded 'tell me what
MFN backs this domU GFN' call, so the dom0 tools can build proper
pagetables and p2m for the pv domU.  Or have you already taken care of
that?

Tim.