diff --git a/xen/arch/x86/acpi/suspend.c b/xen/arch/x86/acpi/suspend.c
index 015e10e30a..044bd81594 100644
--- a/xen/arch/x86/acpi/suspend.c
+++ b/xen/arch/x86/acpi/suspend.c
@@ -53,8 +53,8 @@ void restore_rest_processor_state(void)
     /* Recover syscall MSRs */
     wrmsrl(MSR_LSTAR, saved_lstar);
     wrmsrl(MSR_CSTAR, saved_cstar);
-    wrmsr(MSR_STAR, 0, (FLAT_RING3_CS32<<16) | __HYPERVISOR_CS);
-    wrmsr(MSR_SYSCALL_MASK, XEN_SYSCALL_MASK, 0U);
+    wrmsrl(MSR_STAR, XEN_MSR_STAR);
+    wrmsrl(MSR_SYSCALL_MASK, XEN_SYSCALL_MASK);
 
     wrfsbase(saved_fs_base);
     wrgsbase(saved_gs_base);
diff --git a/xen/arch/x86/x86_64/traps.c b/xen/arch/x86/x86_64/traps.c
index 8d5f901a81..9f0ee0968c 100644
--- a/xen/arch/x86/x86_64/traps.c
+++ b/xen/arch/x86/x86_64/traps.c
@@ -414,8 +414,8 @@ void subarch_percpu_traps_init(void)
     unmap_domain_page(stub_page);
 
     /* Common SYSCALL parameters. */
-    wrmsr(MSR_STAR, 0, ((unsigned int)FLAT_RING3_CS32 << 16) | __HYPERVISOR_CS);
-    wrmsr(MSR_SYSCALL_MASK, XEN_SYSCALL_MASK, 0U);
+    wrmsrl(MSR_STAR, XEN_MSR_STAR);
+    wrmsrl(MSR_SYSCALL_MASK, XEN_SYSCALL_MASK);
 }
 
 void init_int80_direct_trap(struct vcpu *v)
diff --git a/xen/include/asm-x86/processor.h b/xen/include/asm-x86/processor.h
index c506118263..dda8b83078 100644
--- a/xen/include/asm-x86/processor.h
+++ b/xen/include/asm-x86/processor.h
@@ -86,6 +86,9 @@
 
 #define XEN_CR4_PV32_BITS (X86_CR4_SMEP|X86_CR4_SMAP)
 
+/* Common SYSCALL parameters. */
+#define XEN_MSR_STAR (((uint64_t)FLAT_RING3_CS32 << 48) |   \
+                      ((uint64_t)__HYPERVISOR_CS << 32))
 #define XEN_SYSCALL_MASK (X86_EFLAGS_AC|X86_EFLAGS_VM|X86_EFLAGS_RF|    \
                           X86_EFLAGS_NT|X86_EFLAGS_DF|X86_EFLAGS_IF|    \
                           X86_EFLAGS_TF)