3 files changed, 16 insertions, 3 deletions

diff --git a/arch/powerpc/kernel/dbell.c b/arch/powerpc/kernel/dbell.c
index 5b25c8060fd..a892680668d 100644
--- a/arch/powerpc/kernel/dbell.c
+++ b/arch/powerpc/kernel/dbell.c
@@ -28,6 +28,8 @@ void doorbell_setup_this_cpu(void)
 
 void doorbell_cause_ipi(int cpu, unsigned long data)
 {
+        /* Order previous accesses vs. msgsnd, which is treated as a store */
+        mb();
         ppc_msgsnd(PPC_DBELL, 0, data);
 }
 
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 0321007086f..8d4214afc21 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -198,8 +198,15 @@ void smp_muxed_ipi_message_pass(int cpu, int msg)
         struct cpu_messages *info = &per_cpu(ipi_message, cpu);
         char *message = (char *)&info->messages;
 
+        /*
+         * Order previous accesses before accesses in the IPI handler.
+         */
+        smp_mb();
         message[msg] = 1;
-        mb();
+        /*
+         * cause_ipi functions are required to include a full barrier
+         * before doing whatever causes the IPI.
+         */
         smp_ops->cause_ipi(cpu, info->data);
 }
 
@@ -211,7 +218,7 @@ irqreturn_t smp_ipi_demux(void)
         mb();   /* order any irq clear */
 
         do {
-                all = xchg_local(&info->messages, 0);
+                all = xchg(&info->messages, 0);
 
 #ifdef __BIG_ENDIAN
                 if (all & (1 << (24 - 8 * PPC_MSG_CALL_FUNCTION)))
diff --git a/arch/powerpc/sysdev/xics/icp-hv.c b/arch/powerpc/sysdev/xics/icp-hv.c
index 14469cf9df6..df0fc582146 100644
--- a/arch/powerpc/sysdev/xics/icp-hv.c
+++ b/arch/powerpc/sysdev/xics/icp-hv.c
@@ -65,7 +65,11 @@ static inline void icp_hv_set_xirr(unsigned int value)
 static inline void icp_hv_set_qirr(int n_cpu , u8 value)
 {
         int hw_cpu = get_hard_smp_processor_id(n_cpu);
-        long rc = plpar_hcall_norets(H_IPI, hw_cpu, value);
+        long rc;
+
+        /* Make sure all previous accesses are ordered before IPI sending */
+        mb();
+        rc = plpar_hcall_norets(H_IPI, hw_cpu, value);
         if (rc != H_SUCCESS) {
                 pr_err("%s: bad return code qirr cpu=%d hw_cpu=%d mfrr=0x%x "
                         "returned %ld\n", __func__, n_cpu, hw_cpu, value, rc);