[V9 PATCH 4/8] pvh dom0: Add checks and restrictions for p2m_is_foreign

[Mukesh Rathor <mukesh.rathor@oracle.com>]

In this patch, we add some checks and restrictions in the relevant
p2m paths for p2m_is_foreign.

Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
---
 xen/arch/x86/mm/p2m-ept.c |  1 +
 xen/arch/x86/mm/p2m.c     | 12 +++++++++---
 xen/include/asm-x86/p2m.h |  1 +
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index 1728b57..e6a0ef4 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -657,6 +657,7 @@ static void ept_change_entry_type_global(struct p2m_domain *p2m,
 
     BUG_ON(p2m_is_grant(ot) || p2m_is_grant(nt));
     BUG_ON(ot != nt && (ot == p2m_mmio_direct || nt == p2m_mmio_direct));
+    BUG_ON(p2m_is_foreign(nt) || (p2m_is_foreign(ot) && !p2m_is_invalid(nt)));
 
     ept_change_entry_type_page(_mfn(ept_get_asr(ept)),
                                ept_get_wl(ept), ot, nt);
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 9edf8c7..996408a 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -547,6 +547,10 @@ guest_physmap_add_entry(struct domain *d, unsigned long gfn,
         return 0;
     }
 
+    /* foreign pages are added thru p2m_add_foreign */
+    if ( p2m_is_foreign(t) )
+        return -EINVAL;
+
     p2m_lock(p2m);
 
     P2M_DEBUG("adding gfn=%#lx mfn=%#lx\n", gfn, mfn);
@@ -581,9 +585,9 @@ guest_physmap_add_entry(struct domain *d, unsigned long gfn,
             omfn = p2m->get_entry(p2m, gfn + i, &ot, &a, 0, NULL);
             ASSERT(!p2m_is_shared(ot));
         }
-        if ( p2m_is_grant(ot) )
+        if ( p2m_is_grant(ot) || p2m_is_foreign(ot) )
         {
-            /* Really shouldn't be unmapping grant maps this way */
+            /* Really shouldn't be unmapping grant/foreign maps this way */
             domain_crash(d);
             p2m_unlock(p2m);
             
@@ -685,6 +689,7 @@ p2m_type_t p2m_change_type(struct domain *d, unsigned long gfn,
     struct p2m_domain *p2m = p2m_get_hostp2m(d);
 
     BUG_ON(p2m_is_grant(ot) || p2m_is_grant(nt));
+    BUG_ON(p2m_is_foreign(nt) || (p2m_is_foreign(ot) && !p2m_is_invalid(nt)));
 
     gfn_lock(p2m, gfn, 0);
 
@@ -709,6 +714,7 @@ void p2m_change_type_range(struct domain *d,
     struct p2m_domain *p2m = p2m_get_hostp2m(d);
 
     BUG_ON(p2m_is_grant(ot) || p2m_is_grant(nt));
+    BUG_ON(p2m_is_foreign(nt) || (p2m_is_foreign(ot) && !p2m_is_invalid(nt)));
 
     p2m_lock(p2m);
     p2m->defer_nested_flush = 1;
@@ -759,7 +765,7 @@ static int set_typed_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn,
 
     gfn_lock(p2m, gfn, 0);
     omfn = p2m->get_entry(p2m, gfn, &ot, &a, 0, NULL);
-    if ( p2m_is_grant(ot) )
+    if ( p2m_is_grant(ot) || p2m_is_foreign(ot) )
     {
         p2m_unlock(p2m);
         domain_crash(d);
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 8aab0ad..7aa71cc 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -164,6 +164,7 @@ typedef unsigned int p2m_query_t;
 #define P2M_BROKEN_TYPES (p2m_to_mask(p2m_ram_broken))
 
 /* Useful predicates */
+#define p2m_is_invalid(_t)  (p2m_to_mask(_t) & p2m_to_mask(p2m_invalid))
 #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)
-- 
1.8.3.1