linux-kernel - [PATCH AUTOSEL 5.4 078/130] x86/mce: Move the mce_panic() call and 'kill

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Date:   Tue, 22 Dec 2020 21:17:21 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Gabriele Paoloni <gabriele.paoloni@...el.com>,
        Borislav Petkov <bp@...e.de>, Tony Luck <tony.luck@...el.com>,
        Sasha Levin <sashal@...nel.org>, linux-edac@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 078/130] x86/mce: Move the mce_panic() call and 'kill_it' assignments to the right places

From: Gabriele Paoloni <gabriele.paoloni@...el.com>

[ Upstream commit e273e6e12ab1db3eb57712bd60655744d0091fa3 ]

Right now, for local MCEs the machine calls panic(), if needed, right
after lmce is set. For MCE broadcasting, mce_reign() takes care of
calling mce_panic().

Hence:
- improve readability by moving the conditional evaluation of
tolerant up to when kill_it is set first;
- move the mce_panic() call up into the statement where mce_end()
fails.

 [ bp: Massage, remove comment in the mce_end() failure case because it
   is superfluous; use local ptr 'cfg' in both tests. ]

Signed-off-by: Gabriele Paoloni <gabriele.paoloni@...el.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Tony Luck <tony.luck@...el.com>
Link: https://lkml.kernel.org/r/20201127161819.3106432-3-gabriele.paoloni@intel.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/kernel/cpu/mce/core.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index c2a9762d278dd..10f69e045d3ea 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1328,8 +1328,7 @@ void do_machine_check(struct pt_regs *regs, long error_code)
 	 * severity is MCE_AR_SEVERITY we have other options.
 	 */
 	if (!(m.mcgstatus & MCG_STATUS_RIPV))
-		kill_it = 1;
-
+		kill_it = (cfg->tolerant == 3) ? 0 : 1;
 	/*
 	 * Check if this MCE is signaled to only this logical processor,
 	 * on Intel only.
@@ -1364,6 +1363,9 @@ void do_machine_check(struct pt_regs *regs, long error_code)
 		if (mce_end(order) < 0) {
 			if (!no_way_out)
 				no_way_out = worst >= MCE_PANIC_SEVERITY;
+
+			if (no_way_out && cfg->tolerant < 3)
+				mce_panic("Fatal machine check on current CPU", &m, msg);
 		}
 	} else {
 		/*
@@ -1380,15 +1382,6 @@ void do_machine_check(struct pt_regs *regs, long error_code)
 		}
 	}
 
-	/*
-	 * If tolerant is at an insane level we drop requests to kill
-	 * processes and continue even when there is no way out.
-	 */
-	if (cfg->tolerant == 3)
-		kill_it = 0;
-	else if (no_way_out)
-		mce_panic("Fatal machine check on current CPU", &m, msg);
-
 	if (worst > 0)
 		irq_work_queue(&mce_irq_work);
 
-- 
2.27.0