sysemu/xen: Forbid using Xen headers in user emulation

Xen is a system specific accelerator, it makes no sense
to include its headers in user emulation.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20231114143816.71079-3-philmd@linaro.org>

include/sysemu/xen.h

@@ -10,6 +10,10 @@
 #ifndef SYSEMU_XEN_H
 #define SYSEMU_XEN_H
 
+#ifdef CONFIG_USER_ONLY
+#error Cannot include sysemu/xen.h from user emulation
+#endif
+
 #include "exec/cpu-common.h"
 
 #ifdef NEED_CPU_H
@@ -26,16 +30,13 @@ extern bool xen_allowed;
 
 #define xen_enabled()           (xen_allowed)
 
-#ifndef CONFIG_USER_ONLY
 void xen_hvm_modified_memory(ram_addr_t start, ram_addr_t length);
 void xen_ram_alloc(ram_addr_t ram_addr, ram_addr_t size,
                    struct MemoryRegion *mr, Error **errp);
-#endif
 
 #else /* !CONFIG_XEN_IS_POSSIBLE */
 
 #define xen_enabled() 0
-#ifndef CONFIG_USER_ONLY
 static inline void xen_hvm_modified_memory(ram_addr_t start, ram_addr_t length)
 {
     /* nothing */
@@ -45,7 +46,6 @@ static inline void xen_ram_alloc(ram_addr_t ram_addr, ram_addr_t size,
 {
     g_assert_not_reached();
 }
-#endif
 
 #endif /* CONFIG_XEN_IS_POSSIBLE */