v4.19.13 snapshot.
diff --git a/include/xen/xen.h b/include/xen/xen.h
new file mode 100644
index 0000000..1e1d9bd
--- /dev/null
+++ b/include/xen/xen.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _XEN_XEN_H
+#define _XEN_XEN_H
+
+enum xen_domain_type {
+ XEN_NATIVE, /* running on bare hardware */
+ XEN_PV_DOMAIN, /* running in a PV domain */
+ XEN_HVM_DOMAIN, /* running in a Xen hvm domain */
+};
+
+#ifdef CONFIG_XEN
+extern enum xen_domain_type xen_domain_type;
+#else
+#define xen_domain_type XEN_NATIVE
+#endif
+
+#ifdef CONFIG_XEN_PVH
+extern bool xen_pvh;
+#else
+#define xen_pvh 0
+#endif
+
+#define xen_domain() (xen_domain_type != XEN_NATIVE)
+#define xen_pv_domain() (xen_domain_type == XEN_PV_DOMAIN)
+#define xen_hvm_domain() (xen_domain_type == XEN_HVM_DOMAIN)
+#define xen_pvh_domain() (xen_pvh)
+
+#include <linux/types.h>
+
+extern uint32_t xen_start_flags;
+
+#ifdef CONFIG_XEN_DOM0
+#include <xen/interface/xen.h>
+#include <asm/xen/hypervisor.h>
+
+#define xen_initial_domain() (xen_domain() && \
+ (xen_start_flags & SIF_INITDOMAIN))
+#else /* !CONFIG_XEN_DOM0 */
+#define xen_initial_domain() (0)
+#endif /* CONFIG_XEN_DOM0 */
+
+#endif /* _XEN_XEN_H */