x86: TSS busy flag

diff -r 7e00ebe2b7fd xen/arch/x86/hvm/vmx/vmx.c
@@ -624,6 +624,9 @@ static void vmx_load_cpu_state(struct vc
     v->arch.hvm_vmx.cstar     = data->msr_cstar;
     v->arch.hvm_vmx.shadow_gs = data->shadow_gs;
 #endif
+
+    /* The busy flags must be set for Intel */
+    set_bit(1, &data->tr_arbytes);
 
     hvm_set_guest_tsc(v, data->tsc);
 }