powerpc/64s: Invalidate ERAT on powersave wakeup for POWER9

On POWER9 the ERAT may be incorrect on wakeup from some stop states
that lose state. This causes random segvs and illegal instructions
when these stop states are enabled.

This patch invalidates the ERAT on wakeup on POWER9 to prevent this
from causing a problem.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Merge comment change with upstream changes]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 07b79c2c70f8a1a1b2432454aadbe391aabac008..02a82777fd5b09ebf2001185c00b03ac1400c4cf 100644 (file)
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -99,9 +99,11 @@ EXC_VIRT_NONE(0x4000, 0x100)
 #ifdef CONFIG_PPC_P7_NAP
        /*
         * If running native on arch 2.06 or later, check if we are waking up
-        * from nap/sleep/winkle, and branch to idle handler. The idle wakeup
-        * handler initially runs in real mode, but we branch to the 0xc000...
-        * address so we can turn on relocation with mtmsr.
+        * from nap/sleep/winkle, and branch to idle handler. This tests SRR1
+        * bits 46:47. A non-0 value indicates that we are coming from a power
+        * saving state. The idle wakeup handler initially runs in real mode,
+        * but we branch to the 0xc000... address so we can turn on relocation
+        * with mtmsr.
         */
 #define IDLETEST(n)                                                    \
        BEGIN_FTR_SECTION ;                                             \

diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S
index 1ea14b96f1261c723fd0aa6674f0223c333459af..f6518c768d2acdf48c4c3197c67b1b275d8ddb0a 100644 (file)
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -435,6 +435,13 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_ARCH_300)
  * cr3 - set to gt if waking up with partial/complete hypervisor state loss
  */
 pnv_restore_hyp_resource_arch300:
+       /*
+        * Workaround for POWER9, if we lost resources, the ERAT
+        * might have been mixed up and needs flushing.
+        */
+       blt     cr3,1f
+       PPC_INVALIDATE_ERAT
+1:
        /*
         * POWER ISA 3. Use PSSCR to determine if we
         * are waking up from deep idle state