linux-kernel - [PATCH AUTOSEL 6.6 16/58] s390/traps: Handle early warnings gracefully

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Message-ID: <20241004182503.3672477-16-sashal@kernel.org>
Date: Fri,  4 Oct 2024 14:23:49 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Heiko Carstens <hca@...ux.ibm.com>,
	Sven Schnelle <svens@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Sasha Levin <sashal@...nel.org>,
	agordeev@...ux.ibm.com,
	brueckner@...ux.ibm.com,
	linux-s390@...r.kernel.org
Subject: [PATCH AUTOSEL 6.6 16/58] s390/traps: Handle early warnings gracefully

From: Heiko Carstens <hca@...ux.ibm.com>

[ Upstream commit 3c4d0ae0671827f4b536cc2d26f8b9c54584ccc5 ]

Add missing warning handling to the early program check handler. This
way a warning is printed to the console as soon as the early console
is setup, and the kernel continues to boot.

Before this change a disabled wait psw was loaded instead and the
machine was silently stopped without giving an idea about what
happened.

Reviewed-by: Sven Schnelle <svens@...ux.ibm.com>
Signed-off-by: Heiko Carstens <hca@...ux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@...ux.ibm.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/s390/kernel/early.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 3a54733e4fc65..eb6307c066c8a 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -174,8 +174,21 @@ static __init void setup_topology(void)
 
 void __do_early_pgm_check(struct pt_regs *regs)
 {
-	if (!fixup_exception(regs))
-		disabled_wait();
+	struct lowcore *lc = get_lowcore();
+	unsigned long ip;
+
+	regs->int_code = lc->pgm_int_code;
+	regs->int_parm_long = lc->trans_exc_code;
+	ip = __rewind_psw(regs->psw, regs->int_code >> 16);
+
+	/* Monitor Event? Might be a warning */
+	if ((regs->int_code & PGM_INT_CODE_MASK) == 0x40) {
+		if (report_bug(ip, regs) == BUG_TRAP_TYPE_WARN)
+			return;
+	}
+	if (fixup_exception(regs))
+		return;
+	disabled_wait();
 }
 
 static noinline __init void setup_lowcore_early(void)
-- 
2.43.0