1 files changed, 37 insertions, 2 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 23ead298edbd..1170d00879d5 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1410,8 +1410,43 @@ static void __init xen_boot_params_init_edd(void)
  * we do this, we have to be careful not to call any stack-protected
  * function, which is most of the kernel.
  */
-static void __init xen_setup_stackprotector(void)
+static void __init xen_setup_gdt(void)
 {
+        if (xen_feature(XENFEAT_auto_translated_physmap)) {
+#ifdef CONFIG_X86_64
+                unsigned long dummy;
+
+                switch_to_new_gdt(0); /* GDT and GS set */
+
+                /* We are switching of the Xen provided GDT to our HVM mode
+                 * GDT. The new GDT has  __KERNEL_CS with CS.L = 1
+                 * and we are jumping to reload it.
+                 */
+                asm volatile ("pushq %0\n"
+                              "leaq 1f(%%rip),%0\n"
+                              "pushq %0\n"
+                              "lretq\n"
+                              "1:\n"
+                              : "=&r" (dummy) : "0" (__KERNEL_CS));
+
+                /*
+                 * While not needed, we also set the %es, %ds, and %fs
+                 * to zero. We don't care about %ss as it is NULL.
+                 * Strictly speaking this is not needed as Xen zeros those
+                 * out (and also MSR_FS_BASE, MSR_GS_BASE, MSR_KERNEL_GS_BASE)
+                 *
+                 * Linux zeros them in cpu_init() and in secondary_startup_64
+                 * (for BSP).
+                 */
+                loadsegment(es, 0);
+                loadsegment(ds, 0);
+                loadsegment(fs, 0);
+#else
+                /* PVH: TODO Implement. */
+                BUG();
+#endif
+                return; /* PVH does not need any PV GDT ops. */
+        }
         pv_cpu_ops.write_gdt_entry = xen_write_gdt_entry_boot;
         pv_cpu_ops.load_gdt = xen_load_gdt_boot;
 
@@ -1494,7 +1529,7 @@ asmlinkage void __init xen_start_kernel(void)
          * Set up kernel GDT and segment registers, mainly so that
          * -fstack-protector code can be executed.
          */
-        xen_setup_stackprotector();
+        xen_setup_gdt();
 
         xen_init_irq_ops();
         xen_init_cpuid_mask();