From 11cb0a25f71818ca7ab4856548ecfd83c169aa4d Mon Sep 17 00:00:00 2001
From: Nicholas Piggin <npiggin@gmail.com>
Date: Sat, 30 Jan 2021 23:08:35 +1000
Subject: [PATCH] powerpc: improve handling of unrecoverable system reset

References: bsc#1065729
Patch-mainline: v5.12-rc1
Git-commit: 11cb0a25f71818ca7ab4856548ecfd83c169aa4d

If an unrecoverable system reset hits in process context, the system
does not have to panic. Similar to machine check, call nmi_exit()
before die().

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210130130852.2952424-26-npiggin@gmail.com
Fixes: 2b4f3ac56426 ("powerpc: Mark system reset as an NMI with nmi_enter/exit()")
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/kernel/traps.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 3a8699995a77..f70d3f6174c8 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -503,8 +503,11 @@ void system_reset_exception(struct pt_regs *regs)
 		die("Unrecoverable nested System Reset", regs, SIGABRT);
 #endif
 	/* Must die if the interrupt is not recoverable */
-	if (!(regs->msr & MSR_RI))
+	if (!(regs->msr & MSR_RI)) {
+		/* For the reason explained in die_mce, nmi_exit before die */
+		nmi_exit();
 		die("Unrecoverable System Reset", regs, SIGABRT);
+	}
 
 	if (saved_hsrrs) {
 		mtspr(SPRN_HSRR0, hsrr0);
-- 
2.35.3