Traditionally, fatal MCE will cause Linux print error log to console
then reboot. Because MCE registers will preserve their content after
warm reboot, the hardware error can be logged to disk or network after
reboot. But system may fail to warm reboot, then you may lose the
hardware error log. ERST can help here. Through saving the hardware
error log into flash via ERST before go panic, the hardware error log
can be gotten from the flash after system boot successful again.

The fatal MCE processing procedure with ERST involved is as follow:

- Hardware detect error, MCE raised
- MCE read MCE registers, check error severity (fatal), prepare error record
- Write MCE error record into flash via ERST
- Go panic, then trigger system reboot
- System reboot, /sbin/mcelog run, it reads /dev/mcelog to check flash
  for error record of previous boot via ERST, and output and clear
  them if available
- /sbin/mcelog logs error records into disk or network

ERST only accepts CPER record format, but there is no pre-defined CPER
section can accommodate all information in struct mce, so a customized
section type is defined to hold struct mce inside a CPER record as an
error section.
Signed-off-by: NHuang Ying <ying.huang@intel.com>
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

Because more debugfs files under mce dir will be create in mce.c.

ChangeLog:

v5:

- Rebased on x86-tip.git/mce
Signed-off-by: NHuang Ying <ying.huang@intel.com>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

This addresses one of the leftover review comments.

Move the per bank data into a single structure. This avoids
several separate variables and also separate allocation of sysfs objects.

I didn't move the CMCI ownership information so far because
that would have needed some non trivial changes in the algorithms.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

The x86 architecture recently added some new machine check status bits:
S(ignalled) and AR (Action-Required). Signalled allows to check
if a specific event caused an exception or was just logged through CMCI.
AR allows the kernel to decide if an event needs immediate action
or can be delayed or ignored.

Implement support for these new status bits. mce_severity() uses
the new bits to grade the machine check correctly and decide what
to do. The exception handler uses AR to decide to kill or not.
The S bit is used to separate events between the poll/CMCI handler
and the exception handler.

Classical UC always leads to panic. That was true before anyways
because the existing CPUs always passed a PCC with it.

Also corrects the rules whether to kill in user or kernel context
and how to handle missing RIPV.

The machine check handler largely uses the mce-severity grading
engine now instead of making its own decisions. This means the logic
is centralized in one place.  This is useful because it has to be
evaluated multiple times.

v2: Some rule fixes; Add AO events
Fix RIPV, RIPV|EIPV order (Ying Huang)
Fix UCNA with AR=1 message (Ying Huang)
Add comment about panicing in m_c_p.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

The machine check grading (as in deciding what should be done for a given
register value) has to be done multiple times soon and it's also getting
more complicated.
So it makes sense to consolidate it into a single function. To get smaller
and more straight forward and possibly more extensible code I opted towards
a new table driven method. The various rules are put into a table
when is then executed by a very simple interpreter.

The grading engine is in a new file mce-severity.c. I also added a private
include file mce-internal.h, because mce.h is already a bit too cluttered.

This is dead code right now, but will be used in followon patches.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>