xen/xen-os: move inclusion of machine/xen-os.h later

Several of x86 enable/disable functions depend upon the xen*domain()
functions.  As such the xen*domain() functions need to be declared
before machine/xen-os.h.

Officially declare direct inclusion of machine/xen/xen-os.h verboten as
such will break these functions/macros.  Remove one such soon to be
broken inclusion.

Reviewed by: royger
Differential Revision: https://reviews.freebsd.org/D29811

sys/x86/include/xen/xen-os.h

@@ -30,6 +30,10 @@
 #ifndef _MACHINE_X86_XEN_XEN_OS_H_
 #define _MACHINE_X86_XEN_XEN_OS_H_
 
+#ifndef _XEN_XEN_OS_H_
+#error "do not #include machine/xen/xen-os.h, #include xen/xen-os.h instead"
+#endif
+
 /* Shared memory needs write-back as its cache attribute for coherency. */
 #define VM_MEMATTR_XEN VM_MEMATTR_WRITE_BACK
 

sys/x86/xen/xen_intr.c

@@ -57,7 +57,6 @@ __FBSDID("$FreeBSD$");
 #include <machine/stdarg.h>
 
 #include <machine/xen/synch_bitops.h>
-#include <machine/xen/xen-os.h>
 
 #include <xen/xen-os.h>
 #include <xen/hvm.h>

sys/xen/xen-os.h

@@ -71,12 +71,6 @@ xen_get_console_evtchn(void)
 
 	return (hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN));
 }
-#endif
-
-#include <machine/xen/xen-os.h>
-
-/* Everything below this point is not included by assembler (.S) files. */
-#ifndef __ASSEMBLY__
 
 extern shared_info_t *HYPERVISOR_shared_info;
 
@@ -117,6 +111,12 @@ xen_initial_domain(void)
 
 	return (xen_domain() && (hvm_start_flags & SIF_INITDOMAIN) != 0);
 }
+#endif
+
+#include <machine/xen/xen-os.h>
+
+/* Everything below this point is not included by assembler (.S) files. */
+#ifndef __ASSEMBLY__
 
 /*
  * Based on ofed/include/linux/bitops.h