From 272f636445cf556498c8840dc63ad1218e94391b Mon Sep 17 00:00:00 2001
From: Nicholas Piggin <npiggin@gmail.com>
Date: Fri, 2 Aug 2019 20:56:35 +1000
Subject: [PATCH] powerpc/64s/exception: machine check pseries should skip the
late handler for kernel MCEs
References: jsc#PM-1334 jsc#SLE-9246 jsc#SLE-9251
Patch-mainline: v5.4-rc1
Git-commit: 272f636445cf556498c8840dc63ad1218e94391b
The powernv machine check handler copes with taking a MCE from one of
three contexts, guest, kernel, and user. In each case the early
handler runs first on a special stack, then:
- The guest case branches to the KVM interrupt handler (via standard
interrupt macros).
- The user case will run the "late" handler which is like a normal
interrupt that runs in virtual mode and uses the regular kernel
stack.
- The kernel case queues the event and schedules it for processing
with irq work.
The last case is important, it must not enable virtual memory because
the MMU state may not be set up to deal with that (e.g., SLB might be
clear), it must not use the regular kernel stack for similar reasons
(e.g., might be in OPAL with OPAL stack in r1), and the kernel does
not expect anything to touch its stack if interrupts are disabled.
The pseries handler does not do this queueing, but instead it always
runs the late handler for host MCEs, which has some of the same
problems.
Now that pseries is using machine_check_events, change it to do the
same as powernv and queue events for kernel MCEs.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190802105709.27696-11-npiggin@gmail.com
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
arch/powerpc/kernel/exceptions-64s.S | 22 ++--------------------
1 file changed, 2 insertions(+), 20 deletions(-)
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index b7c4149cb91c..aa3720c0b8fe 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1163,7 +1163,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
cmpdi r3,0 /* see if we handled MCE successfully */
beq 1b /* if !handled then panic */
-BEGIN_FTR_SECTION
+
/*
* Return from MC interrupt.
* Queue up the MCE event so that we can log it later, while
@@ -1172,18 +1172,7 @@ BEGIN_FTR_SECTION
bl machine_check_queue_event
MACHINE_CHECK_HANDLER_WINDUP
RFI_TO_KERNEL
-FTR_SECTION_ELSE
- /*
- * pSeries: Return from MC interrupt. Before that stay on emergency
- * stack and call machine_check_exception to log the MCE event.
- */
- LOAD_HANDLER(r10,mce_return)
- mtspr SPRN_SRR0,r10
- ld r10,PACAKMSR(r13)
- mtspr SPRN_SRR1,r10
- RFI_TO_KERNEL
- b .
-ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE)
+
9:
/* Deliver the machine check to host kernel in V mode. */
BEGIN_FTR_SECTION
@@ -1212,13 +1201,6 @@ EXC_COMMON_BEGIN(unrecover_mce)
bl unrecoverable_exception
b 1b
-EXC_COMMON_BEGIN(mce_return)
- /* Invoke machine_check_exception to print MCE event and return. */
- addi r3,r1,STACK_FRAME_OVERHEAD
- bl machine_check_exception
- MACHINE_CHECK_HANDLER_WINDUP
- RFI_TO_KERNEL
- b .
EXC_REAL_BEGIN(data_access, 0x300, 0x80)
EXCEPTION_PROLOG_0 PACA_EXGEN
--
2.23.0