1 files changed, 18 insertions, 5 deletions

diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
index 4753958cd509..b716f666e48a 100644
--- a/arch/powerpc/platforms/powernv/smp.c
+++ b/arch/powerpc/platforms/powernv/smp.c
@@ -149,6 +149,7 @@ static int pnv_smp_cpu_disable(void)
 static void pnv_smp_cpu_kill_self(void)
 {
         unsigned int cpu;
+        unsigned long srr1;
 
         /* Standard hot unplug procedure */
         local_irq_disable();
@@ -165,13 +166,25 @@ static void pnv_smp_cpu_kill_self(void)
         mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);
         while (!generic_check_cpu_restart(cpu)) {
                 ppc64_runlatch_off();
-                power7_nap(1);
+                srr1 = power7_nap(1);
                 ppc64_runlatch_on();
 
-                /* Clear the IPI that woke us up */
-                icp_native_flush_interrupt();
-                local_paca->irq_happened &= PACA_IRQ_HARD_DIS;
-                mb();
+                /*
+                 * If the SRR1 value indicates that we woke up due to
+                 * an external interrupt, then clear the interrupt.
+                 * We clear the interrupt before checking for the
+                 * reason, so as to avoid a race where we wake up for
+                 * some other reason, find nothing and clear the interrupt
+                 * just as some other cpu is sending us an interrupt.
+                 * If we returned from power7_nap as a result of
+                 * having finished executing in a KVM guest, then srr1
+                 * contains 0.
+                 */
+                if ((srr1 & SRR1_WAKEMASK) == SRR1_WAKEEE) {
+                        icp_native_flush_interrupt();
+                        local_paca->irq_happened &= PACA_IRQ_HARD_DIS;
+                        smp_mb();
+                }
 
                 if (cpu_core_split_required())
                         continue;