Re: [Xen-devel] [V11 PATCH 3/4] pvh dom0: Add and remove foreign pages

[Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>]

On Tue, 06 May 2014 08:51:24 +0100
"Jan Beulich" <JBeulich@xxxxxxxx> wrote:

> >>> On 06.05.14 at 03:21, <mukesh.rathor@xxxxxxxxxx> wrote:
> > "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> >> >>> On 02.05.14 at 03:55, <mukesh.rathor@xxxxxxxxxx> wrote:
> >> > @@ -444,6 +451,10 @@ int p2m_alloc_table(struct p2m_domain *p2m)
> >> >      return rc;
> >> >  }
> >> >  
> >> > +/*
> >> > + * pvh fixme: when adding support for pvh non-hardware domains,
> >> > this path must
> >> > + * cleanup any foreign p2m types (release refcnts on them).
> >> > + */
> >> 
> >> And I wonder whether you shouldn't enforce this by disallowing non-
> >> hardware domains to create foreign mappings.
> > 
> > Hmm... Tim wanted the enforcement. That will ensure the cleanup is
> > implemented without falling thru the cracks.
> 
> I'm confused - aren't you stating that Tim requested the same I did?
> Or else, what "enforcement" are you referring to?

Yes, Tim requested enforcement which I added in p2m_add_foreign():

+    /*
+     * pvh fixme: until support is added to p2m teardown code to cleanup any
+     * foreign entries, limit this to hardware domain only.
+     */
+    if ( !is_hardware_domain(tdom) )
+        return -EPERM;

Thus, non-hardware domains can't map foreign types. Not sure if there's
anything worth enforcing in p2m_teardown with above.

I'm not sure I understand what you think "I shouldn't enforce".

Mukesh



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