[PATCH AUTOSEL 5.4 078/130] x86/mce: Move the mce_panic() call and 'kill_it' assignments to the right places

[PATCH AUTOSEL 5.4 078/130] x86/mce: Move the mce_panic() call and 'kill_it' assignments to the right places

[Sasha Levin]

From: Gabriele Paoloni <gabriele.paoloni@intel.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@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20201127161819.3106432-3-gabriele.paoloni@intel.com
Signed-off-by: Sasha Levin <sashal@kernel.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

[PATCH AUTOSEL 5.4 079/130] x86/mce: Panic for LMCE only if mca_cfg.tolerant < 3

[Sasha Levin]

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

[ Upstream commit 3a866b16fd2360a9c4ebf71cfbf7ebfe968c1409 ]

Right now for LMCE, if no_way_out is set, mce_panic() is called
regardless of mca_cfg.tolerant. This is not correct as, if
mca_cfg.tolerant = 3, the code should never panic.

Add that check.

 [ bp: use local ptr 'cfg'. ]

Signed-off-by: Gabriele Paoloni <gabriele.paoloni@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20201127161819.3106432-4-gabriele.paoloni@intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 10f69e045d3ea..344fe08779824 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1344,7 +1344,7 @@ void do_machine_check(struct pt_regs *regs, long error_code)
 	 * to see it will clear it.
 	 */
 	if (lmce) {
-		if (no_way_out)
+		if (no_way_out && cfg->tolerant < 3)
 			mce_panic("Fatal local machine check", &m, msg);
 	} else {
 		order = mce_start(&no_way_out);
-- 
2.27.0