1 files changed, 14 insertions, 1 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index cd022c43dfbc..aed7ceeb4b65 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -66,6 +66,8 @@ EXPORT_SYMBOL_GPL(xen_start_info);
 
 struct shared_info xen_dummy_shared_info;
 
+void *xen_initial_gdt;
+
 /*
  * Point at some empty memory to start with. We map the real shared_info
  * page as soon as fixmap is up and running.
@@ -917,8 +919,19 @@ asmlinkage void __init xen_start_kernel(void)
         have_vcpu_info_placement = 0;
 #endif
 
-        /* setup percpu state */
+#ifdef CONFIG_X86_64
+        /*
+         * Setup percpu state.  We only need to do this for 64-bit
+         * because 32-bit already has %fs set properly.
+         */
         load_percpu_segment(0);
+#endif
+        /*
+         * The only reliable way to retain the initial address of the
+         * percpu gdt_page is to remember it here, so we can go and
+         * mark it RW later, when the initial percpu area is freed.
+         */
+        xen_initial_gdt = &per_cpu(gdt_page, 0);
 
         xen_smp_init();