xen/x86: adjust data placement

Both xen_pvh and xen_start_flags get written just once early during
init. Using the respective annotation then allows the open-coded placing
in .data to go away.

Additionally the former, like the latter, wants exporting, or else
xen_pvh_domain() can't be used from modules.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/8155ed26-5a1d-c06f-42d8-596d26e75849@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>

Author: jbeulich

arch/x86/xen/enlighten.c

@@ -75,7 +75,7 @@ EXPORT_SYMBOL_GPL(xen_have_vector_callback);
  */
 enum xen_domain_type __ro_after_init xen_domain_type = XEN_NATIVE;
 EXPORT_SYMBOL_GPL(xen_domain_type);
-uint32_t xen_start_flags __section(".data") = 0;
+uint32_t __ro_after_init xen_start_flags;
 EXPORT_SYMBOL(xen_start_flags);
 
 /*

arch/x86/xen/enlighten_pvh.c

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/acpi.h>
+#include <linux/export.h>
 
 #include <xen/hvc-console.h>
 
@@ -18,10 +19,11 @@
 /*
  * PVH variables.
  *
- * The variable xen_pvh needs to live in the data segment since it is used
+ * The variable xen_pvh needs to live in a data segment since it is used
  * after startup_{32|64} is invoked, which will clear the .bss segment.
  */
-bool xen_pvh __section(".data") = 0;
+bool __ro_after_init xen_pvh;
+EXPORT_SYMBOL_GPL(xen_pvh);
 
 void __init xen_pvh_init(struct boot_params *boot_params)
 {