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..1508a3b 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 9dc41b4..77fc915 100644
--- a/xen/arch/arm/vsmc.c
+++ b/xen/arch/arm/vsmc.c
@@ -138,7 +138,7 @@ 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, uint32_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 */
@@ -146,7 +146,7 @@ static bool handle_sssc(struct cpu_user_regs *regs)
 {
     uint32_t fid = PSCI_ARG32(regs, 0);
 
-    switch ( fid )
+    switch ( smccc_get_fn(fid) )
     {
     case PSCI_0_2_FN_PSCI_VERSION:
         perfc_incr(vpsci_version);
diff --git a/xen/include/asm-arm/psci.h b/xen/include/asm-arm/psci.h
index be2458a..635ea5d 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
@@ -42,29 +44,24 @@ void do_psci_0_2_system_off(void);
 void do_psci_0_2_system_reset(void);
 
 /* PSCI v0.2 interface */
-#define PSCI_0_2_FN_BASE        0x84000000
-#define PSCI_0_2_FN(n)          (PSCI_0_2_FN_BASE + (n))
-#define PSCI_0_2_64BIT          0x40000000
-#define PSCI_0_2_FN64_BASE      \
-                        (PSCI_0_2_FN_BASE + PSCI_0_2_64BIT)
-#define PSCI_0_2_FN64(n)        (PSCI_0_2_FN64_BASE + (n))
-
-#define PSCI_0_2_FN_PSCI_VERSION        PSCI_0_2_FN(0)
-#define PSCI_0_2_FN_CPU_SUSPEND         PSCI_0_2_FN(1)
-#define PSCI_0_2_FN_CPU_OFF             PSCI_0_2_FN(2)
-#define PSCI_0_2_FN_CPU_ON              PSCI_0_2_FN(3)
-#define PSCI_0_2_FN_AFFINITY_INFO       PSCI_0_2_FN(4)
-#define PSCI_0_2_FN_MIGRATE             PSCI_0_2_FN(5)
-#define PSCI_0_2_FN_MIGRATE_INFO_TYPE   PSCI_0_2_FN(6)
-#define PSCI_0_2_FN_MIGRATE_INFO_UP_CPU PSCI_0_2_FN(7)
-#define PSCI_0_2_FN_SYSTEM_OFF          PSCI_0_2_FN(8)
-#define PSCI_0_2_FN_SYSTEM_RESET        PSCI_0_2_FN(9)
-
-#define PSCI_0_2_FN64_CPU_SUSPEND       PSCI_0_2_FN64(1)
-#define PSCI_0_2_FN64_CPU_ON            PSCI_0_2_FN64(3)
-#define PSCI_0_2_FN64_AFFINITY_INFO     PSCI_0_2_FN64(4)
-#define PSCI_0_2_FN64_MIGRATE           PSCI_0_2_FN64(5)
-#define PSCI_0_2_FN64_MIGRATE_INFO_UP_CPU   PSCI_0_2_FN64(7)
+#define PSCI_0_2_FN32(name) ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,             \
+                                               ARM_SMCCC_CONV_32,               \
+                                               ARM_SMCCC_OWNER_STANDARD,        \
+                                               PSCI_0_2_FN_##name)
+#define PSCI_0_2_FN64(name) ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,             \
+                                               ARM_SMCCC_CONV_64,               \
+                                               ARM_SMCCC_OWNER_STANDARD,        \
+                                               PSCI_0_2_FN_##name)
+#define PSCI_0_2_FN_PSCI_VERSION        0
+#define PSCI_0_2_FN_CPU_SUSPEND         1
+#define PSCI_0_2_FN_CPU_OFF             2
+#define PSCI_0_2_FN_CPU_ON              3
+#define PSCI_0_2_FN_AFFINITY_INFO       4
+#define PSCI_0_2_FN_MIGRATE             5
+#define PSCI_0_2_FN_MIGRATE_INFO_TYPE   6
+#define PSCI_0_2_FN_MIGRATE_INFO_UP_CPU 7
+#define PSCI_0_2_FN_SYSTEM_OFF          8
+#define PSCI_0_2_FN_SYSTEM_RESET        9
 
 /* PSCI v0.2 affinity level state returned by AFFINITY_INFO */
 #define PSCI_0_2_AFFINITY_LEVEL_ON      0
