Re: [Xen-devel] [V9 PATCH 6/8] pvh dom0: Add and remove foreign pages

[Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>]

On Wed, 16 Apr 2014 18:37:42 -0700
Mukesh Rathor <mukesh.rathor@xxxxxxxxxx> wrote:

> On Wed, 16 Apr 2014 17:00:35 +0100
> "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> 
............

> 
> > > +        goto out;
> > > +
> > > +    rc = xsm_map_gmfn_foreign(XSM_TARGET, tdom, fdom);
> > > +    if ( rc )
> > > +        goto out;
> > > +
> > > +    /* following will take a refcnt on the mfn */
> > > +    page = get_page_from_gfn(fdom, fgfn, &p2mt, P2M_ALLOC);
> > > +    if ( !page || !p2m_is_valid(p2mt) )
> > 
> > Is this really p2m_is_valid() (i.e. including various types apart
> > from p2m_ram_rw)?
> 
> Hmm.. let me check again in case of HVM guest coming up on PVH dom0,
> if there are use cases of non-ram types. Otherwise, it could be just
> p2m_is_ram.

Ok, following is the change I'm going to make in the next version
for above comment:

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 67aa5f6..8d3eb95 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1799,7 +1799,7 @@ int p2m_add_foreign(struct domain *tdom, unsigned long fgf
 
     /* following will take a refcnt on the mfn */
     page = get_page_from_gfn(fdom, fgfn, &p2mt, P2M_ALLOC);
-    if ( !page || !p2m_is_valid(p2mt) )
+    if ( !page || !p2m_is_strict_ram(p2mt) )
     {
         if ( page )
             put_page(page);
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 47604da..e0bf6dc 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -165,6 +165,7 @@ typedef unsigned int p2m_query_t;
 
 /* Useful predicates */
+#define p2m_is_strict_ram(_t) (p2m_to_mask(_t) & p2m_to_mask(p2m_ram_rw))
 #define p2m_is_ram(_t) (p2m_to_mask(_t) & P2M_RAM_TYPES)
 #define p2m_is_hole(_t) (p2m_to_mask(_t) & P2M_HOLE_TYPES)
 #define p2m_is_mmio(_t) (p2m_to_mask(_t) & P2M_MMIO_TYPES)


Lmk if you've issues with introducing p2m_is_strict_ram. In that case,
we can just use p2m_is_ram.

thanks
Mukesh

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