P2M: check whether hap mode is enabled before using 2mb pages

This small patch checks whether hap mode is enabled when guest is
trying to allocate 2MB pages inside P2M. This prevents potential
errors when hap is disabled.

Cc: Chris Lalancette <clalance@redhat.com>
Cc: Sarathy, Bhavna <Bhavna.Sarathy@amd.com>
Signed-off-by: Wei Huang <wei.huang2@amd.com>

xen/arch/x86/mm/p2m.c

@@ -1499,7 +1499,11 @@ int set_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn,
 
     while ( todo )
     {
-        order = (((gfn | mfn_x(mfn) | todo) & ((1ul << 9) - 1)) == 0) ? 9 : 0;
+        if ( is_hvm_domain(d) && d->arch.hvm_domain.hap_enabled )
+            order = (((gfn | mfn_x(mfn) | todo) & ((1ul << 9) - 1)) == 0) ?
+                9 : 0;
+        else
+            order = 0;
         rc = d->arch.p2m->set_entry(d, gfn, mfn, order, p2mt);
         gfn += 1ul << order;
         if ( mfn_x(mfn) != INVALID_MFN )