linux-kernel - [PATCH 1/4] x86/mce: do not overwrite no_way_out if mce

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Date:   Wed, 18 Nov 2020 15:15:49 +0000
From:   Gabriele Paoloni <gabriele.paoloni@...el.com>
To:     tony.luck@...el.com, bp@...en8.de, tglx@...utronix.de,
        mingo@...hat.com, x86@...nel.org, hpa@...or.com,
        linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     gabriele.paoloni@...el.com, linux-safety@...ts.elisa.tech
Subject: [PATCH 1/4] x86/mce: do not overwrite no_way_out if mce_end() fails

Currently if mce_end() fails no_way_out is set equal to worst.
worst is the worst severirty that was found in the MCA banks
associated to the current CPU; however at this point no_way_out
could be already set by mca_start() by looking at all severities
of all CPUs that entered the MCE handler.
if mce_end() fails we first check if no_way_out is already set and
if so we stick to it, otherwise we use the local worst value

Signed-off-by: Gabriele Paoloni <gabriele.paoloni@...el.com>
Reviewed-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/kernel/cpu/mce/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 4102b866e7c0..b990892c6766 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1385,7 +1385,7 @@ noinstr void do_machine_check(struct pt_regs *regs)
 	 */
 	if (!lmce) {
 		if (mce_end(order) < 0)
-			no_way_out = worst >= MCE_PANIC_SEVERITY;
+			no_way_out = no_way_out ? no_way_out : worst >= MCE_PANIC_SEVERITY;
 	} else {
 		/*
 		 * If there was a fatal machine check we should have
-- 
2.20.1

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