diff --git a/xen/arch/arm/platforms/seattle.c b/xen/arch/arm/platforms/seattle.c
index 86dce91..22c0622 100644
--- a/xen/arch/arm/platforms/seattle.c
+++ b/xen/arch/arm/platforms/seattle.c
@@ -33,12 +33,12 @@ static const char * const seattle_dt_compat[] __initconst =
  */
 static void seattle_system_reset(void)
 {
-    call_smc(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
+    call_smc(PSCI_0_2_FN32(SYSTEM_RESET), 0, 0, 0);
 }
 
 static void seattle_system_off(void)
 {
-    call_smc(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
+    call_smc(PSCI_0_2_FN32(SYSTEM_OFF), 0, 0, 0);
 }
 
 PLATFORM_START(seattle, "SEATTLE")
diff --git a/xen/arch/arm/psci.c b/xen/arch/arm/psci.c
index 34ee97e..be4e8e6 100644
--- a/xen/arch/arm/psci.c
+++ b/xen/arch/arm/psci.c
@@ -31,9 +31,9 @@
  * (native-width) function ID.
  */
 #ifdef CONFIG_ARM_64
-#define PSCI_0_2_FN_NATIVE(name)	PSCI_0_2_FN64_##name
+#define PSCI_0_2_FN_NATIVE(name)        PSCI_0_2_FN64(name)
 #else
-#define PSCI_0_2_FN_NATIVE(name)	PSCI_0_2_FN_##name
+#define PSCI_0_2_FN_NATIVE(name)        PSCI_0_2_FN32(name)
 #endif
 
 uint32_t psci_ver;
@@ -48,13 +48,13 @@ int call_psci_cpu_on(int cpu)
 void call_psci_system_off(void)
 {
     if ( psci_ver > PSCI_VERSION(0, 1) )
-        call_smc(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
+        call_smc(PSCI_0_2_FN32(SYSTEM_OFF), 0, 0, 0);
 }
 
 void call_psci_system_reset(void)
 {
     if ( psci_ver > PSCI_VERSION(0, 1) )
-        call_smc(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
+        call_smc(PSCI_0_2_FN32(SYSTEM_RESET), 0, 0, 0);
 }
 
 int __init psci_is_smc_method(const struct dt_device_node *psci)
@@ -144,7 +144,7 @@ int __init psci_init_0_2(void)
         }
     }
 
-    psci_ver = call_smc(PSCI_0_2_FN_PSCI_VERSION, 0, 0, 0);
+    psci_ver = call_smc(PSCI_0_2_FN32(PSCI_VERSION), 0, 0, 0);
 
     /* For the moment, we only support PSCI 0.2 and PSCI 1.x */
     if ( psci_ver != PSCI_VERSION(0, 2) && PSCI_VERSION_MAJOR(psci_ver) != 1 )
diff --git a/xen/arch/arm/vsmc.c b/xen/arch/arm/vsmc.c
index d3120a5..5421bd2 100644
--- a/xen/arch/arm/vsmc.c
+++ b/xen/arch/arm/vsmc.c
@@ -114,7 +114,7 @@ static bool handle_existing_apis(struct cpu_user_regs *regs)
 /* helper function for checking arm mode 32/64 bit */
 static inline int psci_mode_check(struct domain *d, register_t fid)
 {
-    return !( is_64bit_domain(d)^( (fid & PSCI_0_2_64BIT) >> 30 ) );
+    return is_64bit_domain(d) || !smccc_is_conv_64(fid);
 }
 
 /* PSCI 0.2 interface and other Standard Secure Calls */
@@ -124,40 +124,40 @@ static bool handle_sssc(struct cpu_user_regs *regs)
 
     switch ( smccc_get_fn(fid) )
     {
-    case smccc_get_fn(PSCI_0_2_FN_PSCI_VERSION):
+    case PSCI_0_2_FN_PSCI_VERSION:
         perfc_incr(vpsci_version);
         PSCI_SET_RESULT(regs, do_psci_0_2_version());
         return true;
 
-    case smccc_get_fn(PSCI_0_2_FN_CPU_OFF):
+    case PSCI_0_2_FN_CPU_OFF:
         perfc_incr(vpsci_cpu_off);
         PSCI_SET_RESULT(regs, do_psci_0_2_cpu_off());
         return true;
 
-    case smccc_get_fn(PSCI_0_2_FN_MIGRATE_INFO_TYPE):
+    case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
         perfc_incr(vpsci_migrate_info_type);
         PSCI_SET_RESULT(regs, do_psci_0_2_migrate_info_type());
         return true;
 
-    case smccc_get_fn(PSCI_0_2_FN_MIGRATE_INFO_UP_CPU):
+    case PSCI_0_2_FN_MIGRATE_INFO_UP_CPU:
         perfc_incr(vpsci_migrate_info_up_cpu);
         if ( psci_mode_check(current->domain, fid) )
             PSCI_SET_RESULT(regs, do_psci_0_2_migrate_info_up_cpu());
         return true;
 
-    case smccc_get_fn(PSCI_0_2_FN_SYSTEM_OFF):
+    case PSCI_0_2_FN_SYSTEM_OFF:
         perfc_incr(vpsci_system_off);
         do_psci_0_2_system_off();
         PSCI_SET_RESULT(regs, PSCI_INTERNAL_FAILURE);
         return true;
 
-    case smccc_get_fn(PSCI_0_2_FN_SYSTEM_RESET):
+    case PSCI_0_2_FN_SYSTEM_RESET:
         perfc_incr(vpsci_system_reset);
         do_psci_0_2_system_reset();
         PSCI_SET_RESULT(regs, PSCI_INTERNAL_FAILURE);
         return true;
 
-    case smccc_get_fn(PSCI_0_2_FN_CPU_ON):
+    case PSCI_0_2_FN_CPU_ON:
         perfc_incr(vpsci_cpu_on);
         if ( psci_mode_check(current->domain, fid) )
         {
@@ -169,7 +169,7 @@ static bool handle_sssc(struct cpu_user_regs *regs)
         }
         return true;
 
-    case smccc_get_fn(PSCI_0_2_FN_CPU_SUSPEND):
+    case PSCI_0_2_FN_CPU_SUSPEND:
         perfc_incr(vpsci_cpu_suspend);
         if ( psci_mode_check(current->domain, fid) )
         {
@@ -181,7 +181,7 @@ static bool handle_sssc(struct cpu_user_regs *regs)
         }
         return true;
 
-    case smccc_get_fn(PSCI_0_2_FN_AFFINITY_INFO):
+    case PSCI_0_2_FN_AFFINITY_INFO:
         perfc_incr(vpsci_cpu_affinity_info);
         if ( psci_mode_check(current->domain, fid) )
         {
@@ -191,7 +191,7 @@ static bool handle_sssc(struct cpu_user_regs *regs)
         }
         return true;
 
-    case smccc_get_fn(PSCI_0_2_FN_MIGRATE):
+    case PSCI_0_2_FN_MIGRATE:
         perfc_incr(vpsci_cpu_migrate);
         if ( psci_mode_check(current->domain, fid) )
         {
diff --git a/xen/include/asm-arm/psci.h b/xen/include/asm-arm/psci.h
index be2458a..8ab8d0a 100644
--- a/xen/include/asm-arm/psci.h
+++ b/xen/include/asm-arm/psci.h
@@ -1,6 +1,8 @@
 #ifndef __ASM_PSCI_H__
 #define __ASM_PSCI_H__
 
+#include <asm/smccc.h>
+
 /* PSCI return values (inclusive of all PSCI versions) */
 #define PSCI_SUCCESS                 0
 #define PSCI_NOT_SUPPORTED          -1
@@ -41,3 +43,3 @@ register_t do_psci_0_2_migrate_info_up_cpu(void);
 void do_psci_0_2_system_off(void);
 void do_psci_0_2_system_reset(void);
 
