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Subject[PATCH 5.9 148/152] x86/mce: Do not overwrite no_way_out if mce_end() fails
Date
From: Gabriele Paoloni <gabriele.paoloni@intel.com>

commit 25bc65d8ddfc17cc1d7a45bd48e9bdc0e729ced3 upstream.

Currently, if mce_end() fails, no_way_out - the variable denoting
whether the machine can recover from this MCE - is determined by whether
the worst severity that was found across the MCA banks associated with
the current CPU, is of panic severity.

However, at this point no_way_out could have been already set by
mca_start() after looking at all severities of all CPUs that entered the
MCE handler. If mce_end() fails, check first if no_way_out is already
set and, if so, stick to it, otherwise use the local worst value.

[ bp: Massage. ]

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>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20201127161819.3106432-2-gabriele.paoloni@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kernel/cpu/mce/core.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1363,8 +1363,10 @@ noinstr void do_machine_check(struct pt_
* When there's any problem use only local no_way_out state.
*/
if (!lmce) {
- if (mce_end(order) < 0)
- no_way_out = worst >= MCE_PANIC_SEVERITY;
+ if (mce_end(order) < 0) {
+ if (!no_way_out)
+ no_way_out = worst >= MCE_PANIC_SEVERITY;
+ }
} else {
/*
* If there was a fatal machine check we should have

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