diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index bb2758819bc9..aa1cc5f015ee 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -1280,6 +1280,15 @@ struct pt_regs;
 
 extern void ppc_save_regs(struct pt_regs *regs);
 
+static inline void update_power8_hid0(unsigned long hid0)
+{
+	/*
+	 *  The HID0 update on Power8 should at the very least be
+	 *  preceded by a a SYNC instruction followed by an ISYNC
+	 *  instruction
+	 */
+	asm volatile("sync; mtspr %0,%1; isync":: "i"(SPRN_HID0), "r"(hid0));
+}
 #endif /* __ASSEMBLY__ */
 #endif /* __KERNEL__ */
 #endif /* _ASM_POWERPC_REG_H */
diff --git a/arch/powerpc/platforms/powernv/subcore.c b/arch/powerpc/platforms/powernv/subcore.c
index f60f80ada903..503a73f59359 100644
--- a/arch/powerpc/platforms/powernv/subcore.c
+++ b/arch/powerpc/platforms/powernv/subcore.c
@@ -190,7 +190,7 @@ static void unsplit_core(void)
 
 	hid0 = mfspr(SPRN_HID0);
 	hid0 &= ~HID0_POWER8_DYNLPARDIS;
-	mtspr(SPRN_HID0, hid0);
+	update_power8_hid0(hid0);
 	update_hid_in_slw(hid0);
 
 	while (mfspr(SPRN_HID0) & mask)
@@ -227,7 +227,7 @@ static void split_core(int new_mode)
 	/* Write new mode */
 	hid0  = mfspr(SPRN_HID0);
 	hid0 |= HID0_POWER8_DYNLPARDIS | split_parms[i].value;
-	mtspr(SPRN_HID0, hid0);
+	update_power8_hid0(hid0);
 	update_hid_in_slw(hid0);
 
 	/* Wait for it to happen */