diff --git a/xen/arch/x86/hvm/viridian/time.c b/xen/arch/x86/hvm/viridian/time.c
index 137577384f..ca6d526f46 100644
--- a/xen/arch/x86/hvm/viridian/time.c
+++ b/xen/arch/x86/hvm/viridian/time.c
@@ -26,6 +26,10 @@ static void update_reference_tsc(const struct domain *d, bool initialize)
     HV_REFERENCE_TSC_PAGE *p = rt->ptr;
     uint32_t seq;
 
+    /* Reference TSC page might not be mapped even if the MSR is enabled. */
+    if ( !p )
+        return;
+
     if ( initialize )
         clear_page(p);