Re: [Xen-devel] [PATCH for-4.10 3/5] tools/dombuilder: Switch to using gfn terminology for console and xenstore rings

[Julien Grall <julien.grall@xxxxxxx>]

Hi Roger,

On 06/10/17 11:36, Roger Pau Monné wrote:
> On Fri, Oct 06, 2017 at 10:03:39AM +0000, Andrew Cooper wrote:
> > On 06/10/17 10:57, Roger Pau Monné wrote:
> > > On Thu, Oct 05, 2017 at 06:23:41PM +0000, Andrew Cooper wrote:
> > > > @@ -612,14 +614,19 @@ static int alloc_magic_pages_hvm(struct xc_dom_image *dom)
> > > >                                  X86_HVM_NR_SPECIAL_PAGES) )
> > > >               goto error_out;
> > > >   
> > > > -    xc_hvm_param_set(xch, domid, HVM_PARAM_STORE_PFN,
> > > > -                     special_pfn(SPECIALPAGE_XENSTORE));
> > > > +    dom->xenstore_gfn = special_pfn(SPECIALPAGE_XENSTORE);
> > > A pre-patch to s/special_pfn/special_gfn/ would be nice :) for
> > > coherency.
> > Sorting out all terminology is a far larger problem than I have time for
> > atm.  For HVM guests, pfn == gfn, so I chose not to dive down that
> > rabbit hole right now.
> Heh, right.
>
> > > > diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
> > > > index ef834e6..0389a06 100644
> > > > --- a/tools/libxl/libxl_dom.c
> > > > +++ b/tools/libxl/libxl_dom.c
> > > > @@ -851,14 +851,9 @@ int libxl__build_pv(libxl__gc *gc, uint32_t domid,
> > > >       if (ret != 0)
> > > >           goto out;
> > > >   
> > > > -    if (xc_dom_translated(dom)) {
> > > > -        state->console_mfn = dom->console_pfn;
> > > > -        state->store_mfn = dom->xenstore_pfn;
> > > > -        state->vuart_gfn = dom->vuart_gfn;
> > > This chunk should go with patch 1, it's a PVHv1 leftover also.
> > Sadly, no its not :(
> >
> > ARM uses libxl__build_pv(), not libxl__build_hvm()
> Really? That's seems very wrong^W confusing IMHO. I'm quite sure that
> with the changes I've made to libxl in PVHv2 ARM could use the HVM
> guest type.
Yes we use PV type for ARM. I think the reason was because HVM would 
create QEMU by default. So PV was more closer here. It might be worth 
having a look how we can re-use the PVH path if it helps maintaining libxl.
Although, this may imply some changes to the user? (I am thinking of 
selecting pvh).
I have created a task on Jira (XEN-102) to keep track of this idea.

Cheers,

--
Julien Grall

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