From aaefca8e30d9df7a4ca13c9c8e135dd227b8ff19 Mon Sep 17 00:00:00 2001 From: Tony Luck Date: Thu, 18 Jul 2019 11:29:20 -0700 Subject: [PATCH] x86/mce: Don't check for the overflow bit on action optional machine checks We currently do not process SRAO (Software Recoverable Action Optional) machine checks if they are logged with the overflow bit set to 1 in the machine check bank status register. This is overly conservative. There are two cases where we could end up with an SRAO+OVER log based on the SDM volume 3 overwrite rules in "Table 15-8. Overwrite Rules for UC, CE, and UCR Errors" 1) First a corrected error is logged, then the SRAO error overwrites. The second error overwrites the first because uncorrected errors have a higher severity than corrected errors. 2) The SRAO error was logged first, followed by a correcetd error. In this case the first error is retained in the bank. So in either case the machine check bank will contain the address of the SRAO error. So we can process that even if the overflow bit was set. Reported-by: Yongkai Wu Signed-off-by: Tony Luck Signed-off-by: Borislav Petkov Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: linux-edac Cc: Thomas Gleixner Cc: x86-ml Link: https://lkml.kernel.org/r/20190718182920.32621-1-tony.luck@intel.com --- arch/x86/kernel/cpu/mce/severity.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c index 210f1f5db5f7..87bcdc6dc2f0 100644 --- a/arch/x86/kernel/cpu/mce/severity.c +++ b/arch/x86/kernel/cpu/mce/severity.c @@ -107,11 +107,11 @@ static struct severity { */ MCESEV( AO, "Action optional: memory scrubbing error", - SER, MASK(MCI_STATUS_OVER|MCI_UC_AR|MCACOD_SCRUBMSK, MCI_STATUS_UC|MCACOD_SCRUB) + SER, MASK(MCI_UC_AR|MCACOD_SCRUBMSK, MCI_STATUS_UC|MCACOD_SCRUB) ), MCESEV( AO, "Action optional: last level cache writeback error", - SER, MASK(MCI_STATUS_OVER|MCI_UC_AR|MCACOD, MCI_STATUS_UC|MCACOD_L3WB) + SER, MASK(MCI_UC_AR|MCACOD, MCI_STATUS_UC|MCACOD_L3WB) ), /* ignore OVER for UCNA */ -- 2.45.2