x86/np2m: add break to np2m_flush_eptp()

Now that np2m sharing is implemented, there can be only one np2m object
with the same np2m_base. Break from loop if the required np2m was found
during np2m_flush_eptp().

Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jun Nakajima <jun.nakajima@intel.com>

xen/arch/x86/mm/p2m.c

@@ -1813,7 +1813,11 @@ void np2m_flush_base(struct vcpu *v, unsigned long np2m_base)
         p2m = d->arch.nested_p2m[i];
         p2m_lock(p2m);
         if ( p2m->np2m_base == np2m_base )
+        {
             p2m_flush_table_locked(p2m);
+            p2m_unlock(p2m);
+            break;
+        }
         p2m_unlock(p2m);
     }
     nestedp2m_unlock(d);

xen/include/asm-x86/p2m.h

@@ -777,7 +777,7 @@ int p2m_pt_handle_deferred_changes(uint64_t gpa);
 void p2m_flush(struct vcpu *v, struct p2m_domain *p2m);
 /* Flushes all nested p2m tables */
 void p2m_flush_nestedp2m(struct domain *d);
-/* Flushes all np2m objects with the specified np2m_base */
+/* Flushes the np2m specified by np2m_base (if it exists) */
 void np2m_flush_base(struct vcpu *v, unsigned long np2m_base);
 
 void nestedp2m_write_p2m_entry(struct p2m_domain *p2m, unsigned long gfn,