powerpc/64: Fix setting of AIL in hypervisor mode

Commit d3cbff1b5 "powerpc: Put exception configuration in a common place"
broke the setting of the AIL bit (which enables taking exceptions with
the MMU still on) on all processors, moving it incorrectly to a function
called only on the boot CPU. This was correct for the guest case but
not when running in hypervisor mode.

This fixes it by partially reverting that commit, putting the setting
back in cpu_ready_for_interrupts()

Fixes: d3cbff1b5a ("powerpc: Put exception configuration in a common place")
Cc: stable@vger.kernel.org # v4.8+
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/setup_64.c

@@ -226,17 +226,25 @@ static void __init configure_exceptions(void)
 		if (firmware_has_feature(FW_FEATURE_OPAL))
 			opal_configure_cores();
 
-		/* Enable AIL if supported, and we are in hypervisor mode */
-		if (early_cpu_has_feature(CPU_FTR_HVMODE) &&
-		    early_cpu_has_feature(CPU_FTR_ARCH_207S)) {
-			unsigned long lpcr = mfspr(SPRN_LPCR);
-			mtspr(SPRN_LPCR, lpcr | LPCR_AIL_3);
-		}
+		/* AIL on native is done in cpu_ready_for_interrupts() */
 	}
 }
 
 static void cpu_ready_for_interrupts(void)
 {
+	/*
+	 * Enable AIL if supported, and we are in hypervisor mode. This
+	 * is called once for every processor.
+	 *
+	 * If we are not in hypervisor mode the job is done once for
+	 * the whole partition in configure_exceptions().
+	 */
+	if (early_cpu_has_feature(CPU_FTR_HVMODE) &&
+	    early_cpu_has_feature(CPU_FTR_ARCH_207S)) {
+		unsigned long lpcr = mfspr(SPRN_LPCR);
+		mtspr(SPRN_LPCR, lpcr | LPCR_AIL_3);
+	}
+
 	/* Set IR and DR in PACA MSR */
 	get_paca()->kernel_msr = MSR_KERNEL;
 }