Patch "powerpc/64: Fix setting of AIL in hypervisor mode" has been added to the 4.8-stable tree

This is a note to let you know that I've just added the patch titled

powerpc/64: Fix setting of AIL in hypervisor mode

to the 4.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
powerpc-64-fix-setting-of-ail-in-hypervisor-mode.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Benjamin Herrenschmidt <[email protected]>
Date: Tue, 15 Nov 2016 15:28:33 +1100
Subject: powerpc/64: Fix setting of AIL in hypervisor mode

From: Benjamin Herrenschmidt <[email protected]>

commit c0a36013639b06760f7c2c21a8387eac855432e1 upstream.

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()

---
 arch/powerpc/kernel/setup_64.c |   20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

@@ -226,17 +226,25 @@ static void __init configure_exceptions(
 		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;
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.8/powerpc-64-fix-setting-of-ail-in-hypervisor-mode.patch