Those functions are used by system/physmem.c, and are called only if
xen is enabled (which happens only if CONFIG_XEN is not set).

So we can crash in case those are called.

Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
---
 hw/xen/xen_stubs.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++
 hw/xen/meson.build |  3 +++
 2 files changed, 59 insertions(+)
 create mode 100644 hw/xen/xen_stubs.c

diff --git a/hw/xen/xen_stubs.c b/hw/xen/xen_stubs.c
new file mode 100644
index 00000000000..19cee84bbb4
--- /dev/null
+++ b/hw/xen/xen_stubs.c
@@ -0,0 +1,56 @@
+/*
+ * Various stubs for xen functions
+ *
+ * Those functions are used only if xen_enabled(). This file is linked only if
+ * CONFIG_XEN is not set, so they should never be called.
+ *
+ * Copyright (c) 2025 Linaro, Ltd.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "system/xen.h"
+#include "system/xen-mapcache.h"
+
+void xen_hvm_modified_memory(ram_addr_t start, ram_addr_t length)
+{
+    g_assert_not_reached();
+}
+
+void xen_ram_alloc(ram_addr_t ram_addr, ram_addr_t size,
+                   struct MemoryRegion *mr, Error **errp)
+{
+    g_assert_not_reached();
+}
+
+bool xen_mr_is_memory(MemoryRegion *mr)
+{
+    g_assert_not_reached();
+}
+
+void xen_invalidate_map_cache_entry(uint8_t *buffer)
+{
+    g_assert_not_reached();
+}
+
+void xen_invalidate_map_cache(void)
+{
+    g_assert_not_reached();
+}
+
+ram_addr_t xen_ram_addr_from_mapcache(void *ptr)
+{
+    g_assert_not_reached();
+}
+
+uint8_t *xen_map_cache(MemoryRegion *mr,
+                       hwaddr phys_addr,
+                       hwaddr size,
+                       ram_addr_t ram_addr_offset,
+                       uint8_t lock,
+                       bool dma,
+                       bool is_write)
+{
+    g_assert_not_reached();
+}
diff --git a/hw/xen/meson.build b/hw/xen/meson.build
index 4a486e36738..a1850e76988 100644
--- a/hw/xen/meson.build
+++ b/hw/xen/meson.build
@@ -9,6 +9,9 @@ system_ss.add(when: ['CONFIG_XEN_BUS'], if_true: files(
 
 system_ss.add(when: ['CONFIG_XEN', xen], if_true: files(
   'xen-operations.c',
+),
+if_false: files(
+  'xen_stubs.c',
 ))
 
 xen_specific_ss = ss.source_set()
-- 
2.39.5

On 3/9/25 21:58, Pierrick Bouvier wrote:
> Those functions are used by system/physmem.c, and are called only if
> xen is enabled (which happens only if CONFIG_XEN is not set).
> 
> So we can crash in case those are called.
> 
> Signed-off-by: Pierrick Bouvier<pierrick.bouvier@linaro.org>
> ---
>   hw/xen/xen_stubs.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++
>   hw/xen/meson.build |  3 +++
>   2 files changed, 59 insertions(+)
>   create mode 100644 hw/xen/xen_stubs.c


Acked-by: Richard Henderson <richard.henderson@linaro.org>


r~